JOURNAL OF APPLIED ENGINEERING SCIENCES · - minimum operational and maintenance costs by eliminating of the regulating and pressure reduction station between the reduced ... regulating

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JOURNAL OF APPLIED ENGINEERING SCIENCES

Volume 2 (15), Issue 2/2012

University of Oradea Publishing House

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EDITORIAL BOARD

EDITOR-IN-CHIEF: Corneliu BOB ([email protected]), Politehnica University of Timi�oara, Romania EXECUTIVE EDITORS: Sanda Monica FILIP ([email protected]), University of Oradea, Romania

Dan GOMBO� ([email protected]), University of Oradea, Romania Aurelian-Stelian BUDA ([email protected]), University of Oradea, Romania Marcela-Florina PRADA ([email protected]), University of Oradea, Romania

MEMBERS

József ÁDÁM – Budapest University of Technology and Economics, Department of Geodesy and Surveying, Hungary

Marian BORZAN – Technical University of Cluj-Napoca, Romania Alexandru C�T�RIG – Technical University of Cluj-Napoca, Romania

Daniel DAN – “Politehnica” University of Timisoara, Romania Petre DRAGOMIR – Technical University of Constructions Bucharest, Romania

Gabriela DROJ – University of Oradea, Romania Mihai ILIESCU – Technical University of Cluj-Napoca, Romania

Ludovic KOPENETZ – Technical University of Cluj-Napoca, Romania Gábor MÉLYKÚTI – University of West Hungary, Faculty of Geoinformatics,

Székesfehérvár, Hungary Johan NEUNER – Technical University of Constructions Bucharest, Romania

Md Azree OTHUMAN MYDIN – Universiti Sains Malaysia, School of Housing, Building and Planning

Maricel PALAMARIU – “1 Decembrie 1918” University of Alba Iulia, Romania

TECHNICAL EDITOR: Gabriela-Argentina POPOVICIU ([email protected]), University of Oradea,

Romania

Aims and Scope: Journal of Applied Engineering Sciences (JAES) is a scientifical journal devoted to presentation and discussion of information on the ultimate issues in the civil, installations, geodesic, electrical and energetical engineering fields. The journal addresses news and various problems which such fields confronts both national and international level. JAES is designed for scientists, researchers (including doctoral students), engineers and managers, regardless of their discipline, who are involved in scientific, technical or other issues related in the journal domains. Emphasis is placed on integrated approaches. These approaches require both technical and non-technical factors. Even the dissemination and application of innovative information is very important, the implementation of existing literature in the JAES related topics and the adress’s contributions also requires a clear understanding from as many other scientific areas as possible.

UNIVERSITY OF ORADEA, FACULTY OF CONSTRUCTIONS AND ARCHITECTURE 4, Barbu �tef�nescu Delavrancea Street, 410058 – ORADEA – ROMÂNIA

www.uoradea.ro * http://arhicon.uoradea.ro * http://www.arhiconoradea.ro/JAES/HOME.htm * Phone/Fax: 004-0259-408447 Cover design by George-Lucian Ionescu

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Preface

The first number of the magazine JOURNAL OF APPLIED ENGINEERING

SCIENCES was published in 1997 under the name of Annals of University of Oradea – CONSTRUCTIONS AND HYDROEDILITARY INSTALLATIONS fascicle. Until 2010 the magazine has been issued annually, thus, it has reached its XIIIth consecutive edition. Since 2003 the magazine has been publishing scientific works presented within the National Conference – international event – MODERN TECHNOLOGIES FOR THE 3rd MILLENIUM, where valuable specialists have met, both from the major university centres in the country and world-renowned professors from universities from abroad. The national and international prestige of the magazine has been constantly increasing.

All scientific papers accepted to publishing are thoroughly analyzed by a scientific committee formed by Romanian and foreign university professors, internationally recognized in their area of expertise.

In 2009 the magazine has undergone an assessment by C.N.C.S.I.S. being rated in category B, and in June 15th 2010 it has been rated B+ by the same C.N.C.S.I.S., being accepted in two International Databases (IDB) – Ulrich’s and Copernicus. Since 2011, the Journal is registered on SCIPIO, the Romanian Publishing Platform website.

Since 2010 the magazine has been issued twice a year, in July (containing scientific papers of Romanian and foreign specialists) and one in November, usually containing scientific papers that had been presented at the National Conference – international event – MODERN TECHNOLOGIES FOR THE THIRD MILLENIUM, the VIIIth consecutive edition being held in 2010. Starting with 2011, the magazine is quarterly published under its new name, JOURNAL OF APPLIED ENGINEERING SCIENCES (JAES), and is in competition for ISI classification.

As a result of the various subjects treated so far in our magazine’s pages, from the Civil engineering and installations, Geodesic engineering, Electrical and energetical engineering in constructions fields, JAES are included in the large Civil Engineering area. It means that the magazine, through the category domain established above, includes resources on the planning, design, construction, maintenance of fixed structures and ground facilities for industry, occupancy, transportation, use and control of water, even harbor facilities. At the same time, resources may cover the sub-fields of structural engineering, geotechnics, earthquake and geodesic engineering, ocean engineering, water resources and supply, marine engineering, transportation engineering, and municipal engineering.

Editorial Staff

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Responsibility for content of the published material exclusively belongs to the authors, the auditing team’s role being to get fit and verify accuracy of those included in these works.

this Review is accredited by C.N.C.S.I.S., code 877, rate B+

(http://cncsis.ro/userfiles/file/CENAPOSS/Bplus_aprilie_2011%281%29.pdf) and it’s registered in the International Database Index Copernicus and Ulrichs

http://journals.indexcopernicus.com/masterlist.php?name=Master&litera=a&start=330&skok=30

http://www.ulrichsweb.com/ulrichsweb/ulrichsweb_news/uu/newTitles.asp?uuMonthlyFile=uu201012/new_titles.txt&Letter=B&navPage=9&

and also in the Scientific Publishing & Information Online SCIPIO Platform http://www.scipio.ro/web/journal-of-applied-engineering-sciences

ISSN / ISSN-L 2247 – 3769 / e-ISSN2284 – 7197 University of Oradea Publishing House October 31, 2012

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CONTENTS

Boeriu Lucia-Maria Redimensioning of gas distribution networks by increasing pressure ………………

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Bota Adrian Unconformable deformations at a reinforced earth structure ……………………….

11

Cazan Oana, M�gureanu Cornelia Time effect on HPC with and without fibers addition ………………………………

17

Cîrstolovean Ioan Lucian, Mizgan Paraschiva Theoretical and practical determinations for establishing the capacity of the radiation heating system - heated concret .......................................................................

23

F�rca� Anagabriela Reverse osmosis water system for industrial use …………………………………..

31

Iacoboaea Cristina, Luca Oana, Gaman Florian Needs and trends in the financing, building and management of social housing ….

37

Iona�cu Anamaria Multipath effect mitigation in signal propagation through an indoor environment …

43

Jocea Andreea Florina 3D spatial data acquisition and modeling of Anghel Saligny Monument using

terrestrial laser scanning ………………………………………………………………..

49Moldovan Radu, M�gureanu Cornelia, Cazan Oana

The study of bond strength and bond durability of high performance concrete …...

55

Muscalu Marius-Teodor, Radu Andrei, Budescu Mihai, ��ranu Nicolae Recycled aggregates and rigid pavement engineering ……………………………..

61

Nari�a Alina-Maria, Mo�oarc� Marius The valorisation of historical sites through architectural interventions ……………

69

Puia Mihaela Simina Services provided by the Romanian Positioning – ROMPOS …………………......

77

Radu Dorin Assessment of the Steel Joints Behavior …………………………………………...

85

Rus Tiberiu GNSS augmentation services in Romania …………………………………………

93

Sandor Florin, Chira Alexandru RC framed building rehabilitated in different ways, subjected to seismic loads …..

101

T�ma� Florin-L., Tuns Ioan Modern method to waterproofing rehabilitation for building infrastructure ………

109

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Todu� Carla, Stoian Valeriu, Nagy-György Tamás, Demeter István Numerical modeling of reinforced concrete wall panels weakened by cut-outs …..

115

Tuns Ioan, Galatanu Teofil-Florin Case study regarding the influence of faults in execution over performance

requirements in a frame steel structure ……………………...…………………………

121

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REDIMENSIONING OF GAS DISTRIBUTION NETWORKS BY INCREASING PRESSURE

BOERIU Lucia-Maria,

Transilvania University of Brasov, e-mail: [email protected]

A B S T R A C T A solution to solve of increasing natural gas consumption is the increasing pressure in existing distribution networks to value of medium pressure. The operation of distribution systems at medium pressure increases economic, technical and energetic efficiency – according to studies developed by the author

Keywords: natural gas distribution system

Received: August 08, 2012 Accepted: August 15, 2012 Revised: September 07, 2012 Available online: October 31, 2012

INTRODUCTION In crowded cities the gas distribution networks have become undersized. Construction

of residential districts in recent years has necessitated expansion of gas networks on large length of the systems originally designed without such reservations.

A solution to the situation of increasing consumption is the increasing pressure in distribution networks, from reduced pressure value to medium pressure value.

MATERIALS AND METHODS 1. Necessity redimensioning of gas networks

The increasing pressure may be applied to polyethylene pipe systems, the steel pipes requiring replacement.

The advantages of rehabilitation of an existing systems are as follows: - minimum operational and maintenance costs by eliminating of the regulating and

pressure reduction station between the reduced pressure systems and the medium pressure systems;

- increasing levels of customer satisfaction to the increase of flow delivered. The disadvantages of rehabilitation of an existing systems could consist of: - long period of execution because the replacement of steel sections with polyetylene; - movement monitoring points of regulating and pressure reduction station in

regulating and metering station; - existence of the replacement costs of used pressure regulating posts (from reduced

pressure to low pressure) with new pressure regulating posts (from medium pressure to low pressure).

The exterior distribution networks are part of the natural gas system, that consists of pipes, equipments, fittings and accessories that take over natural gas from delivery station and transport them to valves branching of consumers.

According to a classical scheme of distribution, the system consists of: - main distribution networks which takes over natural gas at medium pressure (2...6

bar) from regulating and metering station and transport them to regulating and pressure reduction station;

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- distribution networks which takes over natural gas at reduced pressure (0.2...2 bar) from regulating and pressure reduction station and transport them to branching of consumers.

The exterior natural gas distribution networks may have a branched or ring

configuration, supply from a single point (a single regulating and metering station) or multiple points.

Any sizing calculation propose to determine the diameters of all sections so that the pressure loss is minimized and networks cost also be minimum. 2. Studies regarding increasing pressure in gas distribution systems

A first study by the author was performed on an existing distribution system reduced pressure, with branched networks (similar to a city with about 300,000 inhabitants).

By transforming the ring network medium pressure, the maximum transport capacity of the network increased 2.14 times. It follows that the transformation of reduced pressure networks in medium pressure networks do not require resizing of existing networks to take over new customers.

A second study of a distribution system proposed to determine the optimal variant. The following parameters were varied: - network configuration (branched or ring networks); - supply mode (from a single point or multiple points); - increased pressure from reduced pressure value at medium pressure value. Such sizing variants considered two modes of supply systems (from a single points,

through a regulating and metering station or from three points, through three regulating and metering station).

The author also analyzed in terms of technical and economic the distribution function at reduced pressure (1.8 bara) and medium pressure (3.0 bara and 5.0 bara).

The variants studied were the followings: - variant 1 – supply from 3 points, distribution networks medium pressure with 10

regulating and pressure reduction station, branched distribution networks reduced pressure (1.8 bara);

- variant 2 – supply from a single point, branched distribution networks reduced pressure (3.0 bara);

- variant 3 – supply from 3 points, branched distribution networks reduced pressure (5.0 bara);

- variant 4 – supply from 3 points, ring distribution networks medium pressure (5.0 bara);

- variant 5 – supply from 3 points, branched distribution networks medium pressure (3.0 bara);

- variant 6 – supply from a single point, branched networks medium pressure (5.0 bara).

The economic comparison of the six variants showed that the optimal variant is variant 4 – ring network supply from 3 points at medium pressure 5.0 bara.

Graphic, the economic comparison of the six variants of the criterion of „the present value revenue to present value expenses” is a follows:

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-1

1

3

R1R2R3R4R5R6

Variant 4 is slightly higher if we refer to economic efficiency (the ability of an

organization to produce and distribute its products or services at a cost as low and profit as high).

In recent years become important the energetic efficiency of a system: the consumption of energy in order to produce a final good or deliver a service to a final consumer. There is the possibility that an economic unit has a high energy and technical efficiency and low economic efficiency due to the prices used. Lately the price of the primary energy owners has increased significantly. However, there have been temporal oscillations which are reflected in variations in costs. One may encounter such cases in which relatively low energy efficiency may be obscured by the price (e.g. in cases of monopoly). For these reasons, when analyzing the efficiency of a system it is necessary to consider both technical and economic aspects.

The total resource of energy (integrated energy) is the total energy used in successive or parallel technological processes necessary to achieve a product.

The study by author presented in the article „Energetic efficiency evaluation within the natural gas distribution systems redimensioned by increasing the pressure” – proceeding of the 11th WSEAS International Conference on Sustainability in Science Engineering – Timisoara, Romania, May 27-29, 2009 calculated the total energy consumption for each of the six variants. It was resulted that out of the total energy required to achieve the distribution system, the integrated energy in the pipeline material is the highest (between 99.72% and 99.52%).

Again the variant 4 is more advantageous, but is significantly better than the rest of alternatives according to the following graph:

0 5000

10000 15000 20000 25000

Energy consumption

[t.c.f.]

R1 R2 R3 R4 R5 R6

The optimising operation of natural gas distribution networks also includes the using SCADA (Supervisory Control and Data Acquisition) system, with the following advantages:

- continuous monitoring and control of networks parameters;

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- rapid isolation of dangerous areas; - recording operating data of gas natural systems, consultation previous data and

compare them with the existing situation; - possibility of closure and regulation maneuvering equipment of central connection.

CONCLUSIONS

The author conducted a technical and economic investigation of current rehabilitation solutions for natural gas networks in order to find the best options that can be recommended in the future to design distribution networks.

Conclusions can also be applied to resize existing networks in order to ensure an increased flow to consumers.

The transformation reduced pressure networks in medium pressure networks and the transformation branched networks in ring networks ensure optimum operation and flow reserve for new customers.

The optimising operation of natural gas distribution includes an ensemble of measures: - increasing of pressure at medium pressure value; - execution ring networks; - supply from many points; - using the SCADA system for control and monitoring of operation.

ACKNOWLEDGMENTS

The comparative studies described were developed by author in the doctoral thesis elaborated „Contributions to optimisation of natural gas distribution systems”, presented at Transilvania University of Brasov, November 2008.

Conclusions regarding increasing pressure in natural gas distribution also been described by the author in the presentation „Energetic efficiency within the natural gas distribution systems redimensioned by increasing the pressure” of the 11th WSEAS International Conference on Sustainability in Science Engineering – Timisoara, Romania, May 27-29, 2009.

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UNCONFORMABLE DEFORMATIONS AT A REINFORCED EARTH STRUCTURE

BOTA Adrian,

“Politehnica” University of Timi�oara, e-mail: [email protected]

A B S T R A C T In the year 2012 the works at the detour road for Caransebes were finalized. Short time after, the passing structure from the position km 7+375, realized in a „reinforced earth” solution, presented deformations and degradations of some structural elements, which questioned the viability of the bridge. The paper presents some of these defects and tries to explain the phenomenon which leads to them. The remedy solutions will be established after the geotechnical investigations and the analyzing of the evolution of the deformations are done.

Keywords: settling, crack, vault, Freyssisol panel, parapet girder

Received: August 15, 2012 Accepted: September 17, 2012 Revised: September 23, 2012 Available online: October 31, 2012

INTRODUCTION The bridge in discussion is realized in a “reinforced earth” solution and was finalized in

2012, being in exploitation the period of time from 21.12.2011 to 30.05.2012 and from the 31.07.2012 (Fig.1.). The passing structure over the Valley is situated on the national road No.6, on the detour road of Caransebes, at own km 7+735. DN6 (National Road) represents one of the main traffic routes on the East-West direction situated in the south and south-west area of Romania, which connects Bucharest with the cut-off point Cenad in the Timis county, passing the city of Timisoara.

Fig.1. Right lateral view Fig.2. Bridge gauge

In horizontal plane, the bridge is emplaced on a left turning curve with a radius of 950

m. The bridge passes the Valley perpendicularly. In longitudinal profile it finds itself in a slight ramp of 0,3% (Fig.2.).

MATERIALS AND METHODS 1. The structure

The structure was designed and executed based on the Freyssisol technology.

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The passing of the valley is achieved through a vault bridge with a precast concrete vault, with sections, combined with earthwork in reinforced earth solution (3 substructures):

• the Or�ova end – earthwork in reinforced earth solution as a Freyssisol system, 15 m; • the reinforced concrete vault with 1 span of 12,51 m and a hight of 6 m; the vault

consists of 6 adjacent arches, each one composed of 3 precasted elements; the vault is founded on 2 foundation frames out of reinforced concrete, each of them bearing on 2x5 columns; the total length is 17,20 m (Fig.3.);

• the Lugoj end - earthwork in reinforced earth solution as a Freyssisol system, 37 m;

Fig.3. Vault of the main structure

The total length of the structure is 69,30 m, with a maximum height of 12,30 m and an

average height of 10,18 m. For the execution of the work 484 reinforced concrete panels with a thickness of 0,14 m were used, having the standard dimension 2,14 x 1,61 m, adapted to the kind of panel: basic, standard, superior or special.

The width of the bridge of 13,50 m contains the carriage way of 7,00 m and the parapet girders, 1,00 m wide on the right side and 1,10 m on the left side, respectively the carriageable drain of 0,80 m on the left side and the corresponding width of the road shoulder on current section. The bridge gauge is realized without footway, the structure being situated outside the locality.

2. Determined degradations and possible causes

The reinforced earth block is realized continuously, the joint between the above mentioned substructures being visible only at the level of the reinforced concrete slabs.

The vault structure is founded indirectly, with a settling possibility of the foundations practically zero, while the adjacent structures are bewared on surface foundations executed on natural terrain, having therefore possible settlings in time.

The parapet girder is realized as a continuous beam over all the three substructures. Chronologically speaking, the first determined degradations were the horizontal cracks,

which appeared at the superior panels, right under the monolith parapet girder out of reinforced concrete (Fig.4. and Fig.5.).

There are cracked elements also in the proximity of the vault, at panels, which bear directly on the vault, phenomenon owned to the rigid concrete on concrete bearing (Fig.6.).

The appearence of the crack in a slab, which had the movements blocked on the sides parallel with the crack, can be justified by the fact that a torsion phenomenon occured upon

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the superior margin by bearing the parapet girder on a settled earthwork, which simultaneously also lead to the loosening of the tension in the anchorage elements of the slab (Fig.7.).

Fig.4. Cracks in a current element Fig.5. Cracks in a joint element

Fig.6. Cracks in an element leaning on the vault Fig.7. Execution of the parapet girder

The cracking of other slabs on the reinforced earth wall can be similarly justified,

through increasing pressure on the slab, which has a loosened anchorage in a terrain with a distructively modified compaction value. In fact, under normal execution and exploitation conditions, the loading from the anchorages transmits the slab a counter effort to that produced by the earth pressure (Fig.8. and Fig.9).

Fig.8. Intrados parapet girder Fig.9. Contact area parapet girder - panel

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Also the existence of cross cracks was ascertained at the upper side of the parapet girder, on both sides of the bridge (Fig.10-13.). The cracks on the upper surface of the parapet girder, situated not far away from the vertical joint between the substructures, can be explained through the bending of the girder, due to its bearing on the wall out of precast elements and an earthwork which moved vertically, due to settlements.

Fig.10. Left parapet girder - extrados Fig.11. Parapet girder – lateral surface

Fig.12. Right parapet girder - extrados Fig.13. Parapet girder at extrados and lateral surface

The phenomenon recorded about 3 months earlier, consists of relatively large

deformations of the walls, especially at the superior side (over the hight of the last 3 panels), in the direction of their convex bending. The global plane unevenness is around 10 cm on each wall. The phenomenon is more ample on the EAST wall – ramp Orsova, covering the entire length of the wall (Fig.14). On the WEST wall the local plane unevennesses at the joint level between the panels reache aproximately 7 cm (Fig.15). The phenomenon can be explained only by the lengthening of the reinforcement in the polyester. This can occur due to the geometry alteration of the reinforcement in a ground, which has a diminished compaction value. Under the load effect due to earth pressure out of dead load and from traffic, part of the 3% accepted lengthening for the polyester material can take place. Thus the movement of the panels becomes possible in horizontal direction and also the “swelling” of the walls. The diminishing of the compaction value was a consequence of water infiltration from the carriage way through the joint between the asphalt layer and the concrete carriageable drain, during the rainy period from May, when, by reason of the lack of the thin surfacing, the rain water was not draining from the margin of the carriage way, where the asphalt (binder) level was approximately 5 cm lower than the upper level of the drain.

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Fig.14. EAST wall (right) Fig.15. Extreme plane unevennesses of the panels

By enlarging the distance between the walls with about 20 cm, a volume was created,

which was filled with the migration of the filling material, with a thus diminished superior level. The parapet girder, which was bearing on this earthwork has followed its movement, and while lowering, it has rotated around the panel walls, amplifying the fissures and the existing cracks, respectively leading to other new ones.

RESULTS AND DISCUSSIONS 1. Viability state

Analyzing the presented facts referring to the viability state of the bridge on the detour road of Caransebes at km 7+375 over the Valley, situated near the locality Caransebes in the Caras-Severin county, the following can be asserted:

• the constructive elements of the structure present degradations due to an evolutional settling process:

− fissures and cracks at the Freyssisol panels; − craks at the parapet girder; − rotation of the parapet girder; − deformation (plane unevenness) of the walls realized out of Freyssisol panels.

The nuisance value of these degradations for the stability of the structure can be determined only after the investigations regarding the state of the filling material are finalized.

2. Bearing capacity

The bridge was designed for a uniformly distributed load of 20 kPa, which represents 85% from the load provided by the STAS 3221-86 (Carriage way bridges. Standard convoys and loading classes) at chapter 4 – Equivalent in earth layer of the convoys. The mentioned standard makes the assignation, that for the loading class E (which all the passing structures on the detour road for Caransebes are designed for) an equivalent earth layer with a thickness of 1,30 m is considered, which means 23,4 kPa. The determined degradations are not due to the mentioned difference. The calculation did not consider the presence of water, while in the present situation the accidental presence of water in the filling material lead to the altering of its characteristics.

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3. Quality of materials Analyzing by comparison the documentation provided by the contractor, the technical

design and the documents regarding the quality of materials put in place, it can be stated that these are in accordance with the design regulations, as follows (designed/executed):

• Compaction degree filling material � 95% � 100% • Concrete in Freyssisol panels C30/37 C35/45 • Reinforcement in Freyssisol panels Re � 530 MPa Re � 568 Mpa • Concrete in the parapet girder C35/45 C35/45 • Concrete in the vault elements C45/55 C45/55

CONCLUSIONS

For the maintenance of the structure in an adequate viability state, the completion of the investigations is mandatory:

• the determination of the compaction value for the filling as reinforced earth, in different sections in horizontal plane and at different levels in vertical plane, based on a judiciously established plan, in order to avoid the accidental degradation of the anchorage system with polymer reinforcement of the Freyssisol panels;

• the surveying with topographical precision measurements of the evolution of the recorded deformations:

− especially at the upper side of the walls realized out of Freyssisol panels; − at the parapet girder (left and right), which shows rotation towards the carriage

way, but also an extreme bending, which has lead to cracks in the joint area between the substructures.

Considering the large recorded deformations at the above mentioned walls, if the analyse of the investigation results, which are to be done, shows that a consolidation of the structure is needed, it is recommended to use a connection system of the two walls left and right by the means of tie rods introduced horizontaly through the layer between two anchorage levels. The expansion force distribution in the tie rod, respectively the compression force on the panels affected by the deformation, can be achieved through a steel or reinforced concrete girder network, at which the aesthetical aspect will be treated carefully, in order to preserve the slenderness of the structure. Preliminarily the fissures will be sealed by injecting epoxy rasins and the cracks will be repaired with special mortars. The surface thus mended, will receive a colour evenness by dying it with concrete adherent paints, which also have the characteristic of anticorosive protection due to sealing of the microfissures. This consolidation solution can be applied under traffic conditions, by restraining the velocity, on one traffic lane using a traffic light system. Should the accentuation of the parapet girder rotation be determined, extended investigations will be needed, which should clarify the causes leading to the mentioned phenomenon. In accordance to the investigation results, the measures for the maintenance of the structure in an adequate viability state will be established.

ACKNOWLEDGMENTS

The analyse of the passing structure on the detour road of Caransebs at km 7+375 over the Valley was realized as a request of the contractor and the beneficiary, being materialized in the expertise C723/2012 elaborated by SC APECC SRL Timisoara.

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TIME EFFECT ON HPC WITH AND WITHOUT FIBERS ADDITION

CAZAN Oana*, M�GUREANU Cornelia, Tehnical University of Cluj-Napoca,

e-mails:* [email protected] (corresponding adress), [email protected]

A B S T R A C T Physico-mechanical properties of high performance concrete with and without hybrid fibres addition are presented in this paper. The fibres used in this study were a mix of polypropylene and steel. Two types of fibres mixtures were used, 0.60% steel with 0.30% polypropylene and 0.80% steel with 0.22% polypropylene. For the preparation of the specimens just one composition of high strength concrete was used. For all the specimens the concrete class resulting at 28 days was C100. Tests at various ages were performed to establish the time and fibers addition influence on the high performance concrete.

Keywords: polypropylene, steel, compressive strength, splitting tensile strength, energy absorbtion


INTRODUCTION High strength concrete and the ultra high strength concrete will gradually replace the

normal strength concrete [1]. Due to the significant number of research, this concrete that has a compressive strength above 100 MPa, has also many other improved characteristics such as durability, workability, higher elastic modulus, higher tensile and flexural strength, lower permeability and improved abrasion resistance [2]. The fibres addition in this high performance concrete doesn’t has the porpoise to improve the strength, but to alter the behavior of the material once the matrix had cracked, by bridging across these cracks and so providing some post-crack ductility [3]. In spite this reasons, the addition of steel fibers is improving significantly the mechanical strength of the concrete and the addition of polypropylene fibers considerably reduce the amount of shrinkage and explosive spalling when the concrete is exposed to high temperatures (Hammer, Nishida, Atkinson) [4],[5],[6]. There isn’t many informantions on the mechanical and physical properties of high strength concrete containing polypropylene fibers, steel fibers and a cocktail of fibres.

MATERIALS AND METHODS 1. Experimental program 1.1. Materials

Cement: for the preparation of the concrete specimens was used CEM I 52.2 R of “Lafarge”. Microsilica: “ELKEM” silica fume. Aggregates: crushed gravel with the nominal maximum size of 16 mm and crushed sand. The fraction of the aggregate were 0/4 (sand) and 4/8 and 8/16 (gravel). Superplasticizer: Glenium “BASF” additive, ACE 30 Steel fibers: individual Baumix steel fibres, corrugated (table 1). Polypropylene fibers: Eurofibres MF FINE +1217, multifilament, extra-fine (table 1). Typical properties of both steel and polypropylene fibers are presented in table 1.

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Table 1. Properties of the used fibers Properties/types of fibers Steel Polypropylene

Length 25 [mm] 12 [mm] Diameter 400 [�m] 15 [�m] Specific gravity 7850 [kg/m³] 910 [kg/m³] Shape With hooked ends Straight, multifilament Tensile strength 1000 [MPa] 300-400 [MPa] Elastic modulus 210 [GPa] 3.6 [GPa]

1.2. Mixture Proportions

Three batches of high performance concrete were studied. Specimens called OC 1-3 and OC 2-1 are containing both polypropylene and steel fibers addition, but in different proportions. OC 1-3 specimens of C100 grade has 0.60% steel fibers and 0.30% polypropylene fibers addition and OC 2-1 specimens includes 0.80% steel fibers and 0.22% polypropylene fibers. Specimens called AD are witnesses and have no fibers addition and are C100 class, too. The mixture proportions of C100 concrete with and without fibers addition are illustrated in table 2.

Table 2.Concrete mixture Materials/Specimens OC 1-3 OC 2-1 AD

Cement 520 [kg/m³] 520 [kg/m³] 520 [kg/m³] Microsilica 52 [kg/m³] 52 [kg/m³] 52 [kg/m³] Superplasticizer 15.6 [l/m³] 15.6 [l/m³] 15.6 [l/m³] Water 130.68 [l/m³] 128.87 [l/m³] 140.4 [l/m³] Sand 0-4 771.9 [kg/m³] 773.9 [kg/m³] 769.05 [kg/m³] Coarse aggregate 4-8 258.80 [kg/m³] 258.9 [kg/m³] 256.35 [kg/m³] Coarse aggregate 8-16 688.01 [kg/m³] 687.73 [kg/m³] 683.6 [kg/m³] Steel fibers 47.10 [kg/m³] 62.80 [kg/m³] - Polypropylene fibers 2.70 [kg/m³] 2 [kg/m³] - w/cm 0.28 0.28 0.30

1.3. Curing conditions

The curing of the specimens were carried out in accordance with RILEM-Technical Recommendation for Testing and Use of Construction Materials [7]. During the curing the specimens were kept in water with the temperature of 20±2 ºC for 28 days. After removing from water, the specimens that weren’t accomplished the age of testing were moved in the climatic chamber, were the temperaturewas 20±2 ºC and the humidity of 60±5%, until testing age [8]. 1.4. Preparation of the specimens

Crushed aggregates was first added to the mixer, followed by approximately two-thirds of water. In this water were added ahead the polypropylene fibers. After 5 min. of mixing, the cement, the microsilica and the remaining water with the superplasticizer were added gradually to the running mixer. In the end, after the homogenization the steel fibers were added, just for OC 1-3 and OC 2-1 specimens. 2. Tests

Specimens were tested at different ages: 1, 3, 7, 28, 56 and 180 days. Compressive strength (fck ): the compressive strength was determined on three cubes

l = 150 mm, for each age, according to CEB-FIP (fig.1a).

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Splitting tensile strength (fct,sp): the splitting tensile strength was determined on three cubes l = 141 mm, for each age (fig.1b).

Flexural tensile strength (fct,fl): the flexural tensile strength was determined on three 100x100x550 mm prisms, for each age (fig.1c).

Modulus of elasticity (Ecm): was determined on three 100 x 100 x 300 mm prisms, for each age, loaded and unloaded at a rate of 0.1MPa/s, between 0.05 fcm,pr and 0.4 fcm,pr until the stabilization of strains was achieved, according to EC2 (fig.4).

Energy absorbtion (GF): determined on three 40x100x475 mm prisms, for each age, loaded up to failure, whit constant displacement speed, at a rate of 100�m/min (fig.5).

Fig.1. Tests on HPFRC (a-compressive strength, b-splitting tensile strength, c-flexural tensile strength)

Fig.2. Tests on HPFRC (a-mudulus of elasticity, b-energy absorbtion)

a b c

a b

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RESULTS AND DISCUSSIONS 1. Compressive strength

As we observe in fig.3, at the age of 28 days, the addition of fibres leads to a minor increasment of the compressive strength. The compressive strength of OC 2-1 specimens is with 8% bigger than witnesses specimens, AD. Regardin the compressive strength at 28 days of OC 2-1 specimens toward OC 1-3 specimens, their compressive is bigger with 9%.

Fig.3. Evolution of the compressive strength

2. Splitting tensile strength

In fig.4 we can observe a better behavior of OC 2-1 specimens due to the fact that steel fibres are reducing crack propagation and are increasing the concrete ductility. OC 2-1 specimens are characterizaed by values of the splitting tensile strength with 5% bigger, towards OC 1-3 specimens that have a smaller addition of steel fibres.

Fig.4. Evolution of the splitting tensile strength

3. Flexural tensile strength

Fig.5 presents the evolution in the of the tensile flexural strength of the specimens with fibres addition. We can remark a better behavior of OC 2-1 specimens in relation with OC 1-3 specimens. Specimens containing 0.80% steel and 0.22% PP fibres (OC 2-1) are indicating an appreciation with 24% up against the specimens containing 0.60% steel and 0.30% PP fibres (OC 1-3).

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Fig.5. Evolution of tensile flexural strength

4. Modulus of elasticity

The development of modulus of elasticity has in time is presented in fig.6. The difference between OC 2-1 specimens and OC 1-3 specimens at 28 days is 7%.

Fig.6. Evolution of modulus of elasticity

5. Energy absorbtion

Fig.7 and fig.8 are presenting the values of the energy absorbtion of the specimens with fibres addition at 28 days. OC 2-1 specimens have a better energy absorbtion. The difference between OC 2-1 specimens and OC 1-3 specimens is 34%.

Fig.7. Energy absorbtion for OC 1-3 Fig.8. Energy absorbtion for OC 2-1

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CONCLUSIONS Based on the experimental program several conclusions were drawn: 1. High performance concrete with fibres addition shows a better behavior, that the high

performance concrete without fibres addition. 2. The compressive strength grows with 9% for the high performance concrete with

fibres addition. 3. Additional 0.20% steel fibres brings a gain of 5% for the tensile splitting strength. 4. In case of the flexural tensile strength the addition of steel fibres for OC 2-1

specimens brings a 24% plus for the strength. 5. Modulus of elasticity has a liniar behavior until he reaches 56 days. After 56 days the

modulus of elasticity flattes out, but anyway the difference of value between OC 2-1 and OC 1-3 specimens is 7% at 28 days.

6. In the case of the energy absorbtion, the difference between OC 2-1 and OC 1-3 specimens is 34% at 28 days. That difference is attributed to the extra amount of 0.20% of fibres addition.

7. We concluded that the additional steel fibres in OC 2-1 specimens increased significantly all the physico-mechanical properties of the high performance concrete.

ACKNOWLEDGMENTS

This paper was supported by the project "Improvement of the doctoral studies quality in engineering science for development of the knowledge based society-QDOC” contract no. POSDRU/107/1.5/S/78534, project co-funded by the European Social Fund through the Sectorial Operational Program Human Resources 2007-2013.

REFERENCES 1. P. PLIYA, A-L. BEAUCOUR, A. NOUMOWÉ (2011), Elsevier, Construction and Building

Materials 25, pp. 1926-1934. 2. P-C. AÏTCIN (1998), High Performance Concrete, E & FN SPON, London and New-York,

Aug.24. 3. A. BENTUR and S. MINDESS (2007), Fiber Reinforced Cemetious Composites, Modern

Concrete Tehnology Series, Second Edition, London and New-York. 4. HAMMER T.A. (1992), High strength concrete, Phase 3, SP6 fire resistance-report 6.2, Spalling

reduction through material design, SINTEF report, Norway. 5. NISHIDA A, YAMAZAKI N, INOUE H, SCHNEIDER U, DIEDERICHS U. (1995), Study on

the properties of high-strength concrete with short polypropylene fibre for spalling resistance, Proceeding of international conference on concrete under severe conditions, Japan.

6. ATKINSON T. (2004), Polypropylene fibers control explosive spalling in high-performace concrete.

7. *** (1994), International Union of Testing and Research Laboratories for Materials and Structures, Recommendations for Testing and Use of Constructions Materials, E&FN SPON.

8. C. M�GUREANU, O. CAZAN and V. BARNA (2011), High performance concrete at elevated temperatures, Proceedings of DEDUCON International Conference, pp. D7-D15.

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THEORETICAL AND PRACTICAL DETERMINATIONS FOR ESTABLISHING THE CAPACITY OF THE RADIATION

HEATING SYSTEM - HEATED CONCRETE

CÎRSTOLOVEAN Ioan Lucian*, MIZGAN Paraschiva University Transilvania Brasov, Faculty of Buildings Engineering,

*e-mails: [email protected] (corresponding adress), [email protected]

A B S T R A C T A compatibility analysis of thermal energy production supposed to establish if the set tolerances by specifications are compatible with the installations’ capacity of satisfying these demands. As in every production process, its quality characteristics are submitted to some influences having systematic and hazard or chance causes. Systematic causes generate a trend of systematic deviations from the specifications of the thermal agent characteristics. Hazard deviations, thus with a chance character, can be statistically evaluated, the performance of the system being given by the statistic characteristics of dispersion, the most representative being the dispersion, the medium deviation respectively (empiric), the variation coefficient, the amplitude of the recording series. The capability of the generation of thermal energy process represents one of the fundamental criteria referring to the achievement of quality and performance of the system.

Keywords: capability, thermal energy, radiation, radiant panel, thermal storage capacity Received: July 26, 2012 Accepted: July 31, 2012 Revised: August 08, 2012 Available online: October 31, 2012

INTRODUCTION The heating system by low temperature radiation also called „heated concrete” represents a simple solution to be used in building elements as heating objects, the heat transfer from the heating objects to rooms being done mostly by radiation. The thermal agent pipes, as heat transporters, are inserted in the concrete at the level of floors, respectively, the floors of the rooms, the temperature of the thermal agent being under 30° C. The solution of heat accumulation in the mass of the building element [4], of the concrete, and its transfer to rooms represents a solution for increasing the thermal comfort from within the buildings and a method of an efficient use of heat sources which function on renewable energies. The stocking of the heat in the concrete mass at the level of plates which separate the floors of a building is done by using high density polyethylene pipes and thermal agents with lower parameters. The accumulation of heat in ceiling / floors will ensure an efficient overtaking without any thermal variations of highest values during the heating period. The thermal establishment of the building element is aimed at keeping the temperature at the surface of the element within a range of 0,3° C . MATERIALS AND METHODS

In this research we intend to present the variation of temperature on the surface of the building element (floor / heated ceiling) for different values of the thermal agent which runs through the pipes introduced in the concrete and the temperature in the rooms. The study is based on the theoretical calculus as well as on the laboratory measurements. For theoretical calculi on the radiant floor on the upper and lower side are determined by the relations [5]:

tp=ti + �(tag-ti)-kb(l-�)(ti-t’i)] [°C] (1)

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t’p=ti + �(tag-ti)+kb(l-�)(ti-t’i)] [°C] (2)

where: tp= temperature on the radiant lower side plate. [°C]; t’p= temperature on the radiant upper side plate [°C]; ti= inner temperature of the room where the radiant panel is located, [w/m2k]; �p,��p= heat transfer coefficients from the surfaces of the radiant panel [w/m2k]; b,c= partial coefficient of thermal transfer,[w/m2k];

b , c [w/m2k] (3)

� = coefficient that is determined by the relation:

� ), (tgh-hyperbolic tangent ); (4)

m (5)

where: tag= temperature of the thermal agent, [°C]. b,c= thermal conductivity of the material layers from above and below the pipe, [w/mk];

The radiant plate studied in the laboratory is the one presented below [5]:

bc

d

l

q'

q

t'p

tp

Fig.1. The Structure used for the thermal calculus [5]

Fig.1a. The structure of the heating radiant plate

‘heated concrete’ from the laboratory

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Fig.2a. The placement of sensors on the concrete plate

Fig.2b. The placement of sensors on the concrete plate

Fig.2c. The placement of sensors on the concrete plate

1. The capacity of the ‘heated concrete’ radiant system 1.1. The thermal transfer process made by the radiant plate [2] described in Fig. 1 can be

treated as a regulated process on condition we obtain the coincidence of the static average−x ,

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of the measured values (temperature on the surface of the plate), with the CT tolerance centre defined by:

CT=2

is TT −, (6)

T s and T i being the upper respectively the lower specified tolerance limits. Actually, an exact coincidence is not achieved, but an interval is defined, regularly symmetric next to the

tolerance centre, where, if −x , is situated, it can be considered that the process is regulated. If

the condition of a regulated process is not fulfilled, then one actions upon the system in the sense of correcting its functioning for the regulation of the process. 1.2. The thermal transfer process can be irregular even when it is regulated [2]. A process is considered irregular when the amplitude of the natural dispersion 6σ , where 99,73% of the measured and recorded data fall, are not included in the tolerance field having the dimension T=T s -T i . The correction of this situation is done by diminishing of the square, empirical average deviation of the series of recorded data. In this sense, the values around the average should concentrate more and extreme values should be diminished, without increasing the average value. If the process is irregular and imprecise, the interventions on the functioning of the process should be aimed at both deviations, so that the modification directions are convergent.

The stable process [2] is regulated, thus centered, namely, as established, the −x

average and the centre of the tolerance field coincide and the natural limits of the process 6σ are included in the T tolerance field. We calculate the capacity central indices:

C =σ6T

(7)

The optimal value for C [2] is between 1,33-1,66, but a value higher than 1 illustrates that the process is capable, but, for safety, an interval situated in the field 1.33-1,66 is admitted.

Because the distribution of the measured values is not always rigorously symmetrical C pi and C ps , are calculated by using for checking [3]:

C p = min (C pi , C ps ), (8) where:

C pi =σ3LTIx−

−

, C ps =σ3

−− xLTS

, (9)

The indices C p has to satisfy similar conditions with C. For the interval σ3± there are

99,73% from the values recorded in an observation, in the interval σ2± there are 95% from the measured values, and in the interval σ± there are only about 68% from the values. Certain deviations depending on the system and evaluation manner of the capacity can be , as it has been demonstrated, tolerated restrictively. �

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RESULTS AND DISCUSSIONS The laboratory-based measurements were made on a concrete plate into which

polyethylene curved pipes were introduced according to the detail in Fig.1a. The sensors were placed on the surface of the plate according to Fig.2a. The measurements were made between 4.00 -8.00. 234 values were recorded corresponding to every sensor.

The establishment of the tolerance field has been done on the basis of some normative general indications, the most frequently mentioned, namely:

a) the ensurance of a minimal temperature of 20˚C on the surface of the plate; b) the achievement of a maximal temperature of 25˚C on the surface of the plate. It has been appreciated that between these limits, a tolerance field can be established,

the inferior and superior limits being accepted to fluctuate. For example, it has been considered: T i = 20˚C, T s = 25˚C, the variations of these limits could go to 1˚C.

The recorded temperatures were noted by x. For the statistic analysis [1], 8 sub-intervals have been considered. The development of

the calculi is presented in Table 2. The results of the theoretical calculus presented in Table 1 are obtained in the following

conditions: 1. The temperature in the room is 20˚ C above and below the plate; 2. The temperature of the thermal agent is the temperature which was used during

measurements; 3. The pipe that is used is polyethylene and copper in the two examples with their

correspondingly thermal conductivity ; 4. The thickness of the concrete layer from above and beneath pipes is the one taken into

consideration in measurements. For the measuring variant it can be considered that the process is regulated, the

deviations between average and CT being:

0186.05,22

5,2292.22 =−

where: x = 22.92 and average = 22.5

So, in the admissible domain, equally it results that the process is also precise:

T=T is T− =25-20=5 ˚C The C capacity indices:

��σ6T� 31.2

16.25 = ��

The C ps and C pi are calculated:

C pi = 70.208.1

2092.223

=−=−

−

σiTx

C 92.108.1

92.22253

=−=−

=−

σxTs

ps

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Table 1. The results of the theoretical calculus

The calculus of the average temperature on the upper surface of the plate, b=9cm,c=9cm and the PE

pipe d=20 mm ti �� 'p � Tag t'i kb L t'p �(tag-ti) kb(l-�)(ti-t"i) �(tag-ti)-kb(l-�)(ti-t"i) c/�p c/�p *[�(tag-ti)-kb(l-�)(ti-t"i)]

20 6.35 8 0,48 23 20 0,55 0,15 21,14 1,44 0 1,44 0,79 1,14

The calculus of the average temperature

on the surface of the plate Jos ti �� p � Tag t'i kb L tp �(tag-ti) kb(l-�)(ti-t"i) �(tag-ti)-kb(l-�)(ti-t"i) c/�p c/�p *[�(tag-ti)-kb(l-�)(ti-t"i)]

20 4.99 5 0,48 23 20 0,55 0,15 21,43 1,44 0 1,44 0,99 1,43

The calculus of the average temperature on the upper surface of the plate b=9cm,c=9cm, Co pipe d=10 cm

ti b �'p � Tag t'i kb l t'p �(tag-ti) kb(l-�)(ti-t"i) �(tag-ti)-kb(l-�)(ti-t"i) c/�p c/�p *[�(tag-ti)-kb(l-�)(ti-t"i)]

20 6,59 8 0,99 23 20 0,56 0,15 22,46 2,99 0 2,99 0,82 2,46

The calculus of the average temperature

on the surface of the plate ti c �p � Tag t'i kb l tp �(tag-ti) kb(l-�)(ti-t"i) �(tag-ti)-kb(l-�)(ti-t"i) c/�p c/�p *[�(tag-ti)-kb(l-�)(ti-t"i)]

20 5,13 5 0,99 23 20 0,56 0,15 23,07 2,99 0 2,99 1,02 3,07

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Table 2. The results of the static calculus

Sensor Interval values Min Max

Interval centered

values

Number of appearances

in the interval

The average between the

centered value and

the interval frequency

Deviations

−

−

−

=

)(

92.22

xx

x

k

The square of deviations

2)(−

− xxk

n k

2)(−

− xxk

S3.1 22,34 23,58 22,96 24 551,04 0,04 0,0016 0,0384

S3.2 22,65 23,89 23,27 26 605,02 0,35 0,1225 3,185

S3.3 22,8 23,89 23,345 0 0 0,425 0,180625 0 S3.4 22,49 23,58 23,035 0 0 0,115 0,013225 0

S3.5 22,49 23,58 23,035 0 0 0,115 0,013225 0

S3.6 22,49 23,42 22,955 0 0 0,035 0,001225 0

S3.7 22,3 22,96 22,63 0 0 -0,29 0,0841 0

S3.8 22,03 22,65 22,34 17 379,78 -0,58 0,3364 5,7188

S3.9 21,87 22,65 22,26 0 0 -0,66 0,4356 0

Total 67 1535,84 1,188 8,94

The thermal agent Heated water Heated water Total 5128,63 5066,4

Nr measurements 221 221 Average thermal agent 23,20647/tur 22,92489/retur

CONCLUSIONS

• The obtained average temperature on the surface of the plate by a theoretic calculus is 21,14° C, after the measurements of the average temperature on the surface of the plate is 22.92° C. A 7,7% deviation is noticed, deviation which is considered acceptable.

• The recorded temperatures on the radiant surface, the recorded values and the determinations presented above shows that the radiant process analyzed is precise and capable;

• With the shrinking of the T interval, the process remains precise, but it can become irregular which presupposes an action on the temperature of the agent in the sense that the modification of the temperature on the radiant surface.

• Given the concrete mass and if we take into consideration the heat accumulation in the mass of the element it is possible that the temperatures on the surface become level, by concentrating all values of the temperature measured at very close values, therefore, a process permanently precise.

REFERENCES 1. MOCANU, R., UNGUREANU, N. (1982), Strength of materials, Material tests; Cap. Statistic design to

experimental results, Ed Tehnic�, Bucharest. 2. CÎRSTOLOVEAN, L. (2009), Contribu�ii privind realizarea performan�ei prin calitate în concep�ia �i

realizarea instala�iilor pentru construc�ii (Contributions concerning the fulfilment of the performance by quality in the development and achievement of the installations for building). PhD Thesis, Universitatea Tehnic� “Ghe Asachi “Ia�i, Îndrum�tor prof .dr. ing. Nicolae Ungureanu.

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3. DHILLON, B.S. (2007), Applied Reliability and Quality Fundamentals, Method and Procedures, Springer Series in Reliability Engineering series, Springer-Verlag, London, ISSN 1614-7839, ISBN 978-1-84628-497-7, e-ISBN 978-1-84628-498-4.

4. BJARNE,W.O. (2011), Operation and control of thermally activated building systems (TABS), The REHVA European HVAC Journal, Vol. 48, ISSUE 6, www.rehva.eu.

5. *** (2010), Manualul de Instala�ii de Înc�lzire (Heating systems manual), Editura Artecno Bucure�ti.

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REVERSE OSMOSIS WATER SYSTEM FOR INDUSTRIAL USE

F�RCA� Anagabriela, Technical University of Cluj-Napoca, e-mail: [email protected]

A B S T R A C T This paper presents the use of reverse osmosis in water treatment. Reverse osmosis is a baromembrane process that separates water from a solution as a result of pressure. The water and the water solution are separated by a membrane that allows only the water molecules to pass through. The case study represents a reverse osmosis equipment that purifies water for a technological process. In order to observe and test the efficiency of this system it was taken water samples in different phases of the process. In analyzing the water samples it was taken into account the following parameters: manganese, iron, ammonium, turbidity, pH levels, conductivity, permanganate index, water hardness and chlorides. The values of these parameters were compared to the limiting values stipulated by the law. Using the two-stage reverse osmosis process a high efficiency will be achieved.

Keywords: membrane, baromembrane processes, water conductivity, water treatment

Received: July 31, 2012 Accepted: July 31, 2012 Revised: August 10, 2012 Available online: October 31, 2012

INTRODUCTION Osmosis is a natural phenomenon which occurs when two water solutions with different ion

concentration are separated by a semi-permeable membrane [1]. The semi-permeable membranes only allow the water molecules to pass through, therefore the water would flow towards the highly concentrated solution until the two solutions are equally concentrated. For the water to flow towards the less concentrated solution, a force should be applied on the highly concentrated solution. This is the reverse osmosis process, which provides water separation from different water sources.

The membrane is an interposed structure between two phases or compartments which can prevent or aggravate substance transport or which can allow only certain particles to pass through. The separation will take place on the membrane surface or inside the membrane, where the molecular interactions take place. The permeability trough membrane implies both the occurrence of diffusion and the solubility of the diffusing species, but in order for the components to be transferred through the membrane, a driving force is necessary [1]. In the reverse osmosis process the driving force is pressure.

On an economic level, the membrane is supposed to block some substances and to allow the water molecules to pass through.

Fig.1. Membran schematic diagram [1]

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MATERIALS AND METHODS 1. The Experimental Equipment / System

The paper presents a reverse osmosis equipment that purifies water pulled from a 35 meter deep well. The resulting water is used for a tehnological process. The process optimum functioning parameters are equal to the drinking water quality parameters, as regulated by the 458/2002 and 311/2004 laws.

Fig.2. Two-stage reverse osmosis equipment

The reverse osmosis equipment is supplied with water from a well, using a 32 mm wide pipe,

with a 5.7 m3/h flow. A 5 µm filter stops any contingent impurities and manometers measure the filter clogging degree both upstream and downstream. The water hardness is measured by a device located before the manometer which is placed in front of the filter. The samples to be analyzed are collected from the tap, located after the filter. The pressure needed for the reverse osmosis process is produced by a vertical multistage centrifugal pump. Downstream from it two manometers are installed, the first belongs to the pump, and the second is meant for observing the pressure of water entering the first stage of reverse osmosis. At this stage a polyamide and polysulphones spiral-membrane module is provided. The first stage permeate quantity is measured by a flow gauge set on the permeate pipe. The first stage reject is redirected towards the second stage of the reverse osmosis process, where there is another polyamide and polysulphones spiral-membrane module. The second stage permeate is collected together with the first stage permeate. Some of the concentrate resulted from the second stage of the reverse osmosis process is recycled - it re-enters the process right before the reverse osmosis pump, and the rest of it, is evacuated in the sewer system. The samples for the two reverse osmosis stages are provided by the two faucets installed after each membrane module. The resulting permeate and concentrate quantities are determined by flow gauges found downstream from the membrane modules. A pipe that would allow a certain amount of permeate re-enter back in the reverse osmosis system is optional.

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Fig.3. Functional diagram of two stage reverse osmosis equipment (1 – Manometer before the filter; 2 – Filter

cartridge 5 µm; 3 – Manometer before the filter; 4' – Sampling valve; 4 – electro-valve; 5 – Pressure switch; 6 – CR 10-14 Pump; 7 – Pump manometer; 8 – Ball valve; 9 – Entering pressure manometer; 10 – Permeate entering ball valve; 11 – Stage I module membrane; 12 – Stage II

module membrane; 13– Stage I sampling valve; 14 – Stage II sampling valve; 15 – Stage II concentrate manometer; 16 –electro-valve; 17 – Concentrate control needle valve; 18 – Control ball valve for recycled concentrate from stage I; 19 – Stage I concentrate flow gauge; 20 – Stage I

concentrate one-way valve; 21 – Permeate one-way valve; 22 – Permeate flow gauge; 23 – Permeate 3-way valve; 24 – Concentrate 3-way valve; 25 – Concentrate flow gauge; 26 – Permeate measuring element; 27 – One-way valve; 28 – electro-valve; 29 – electro-valve; 30 – Water hardness

monitoring unit)

In order to analyze the efficiency of the reverse osmosis system, samples are collected as

water enters the system, after the first stage and after the second stage. As shown above, special valves are placed for analytical sampling.

2. Methods of Water Analysis The water samples have been collected on a weekly basis and have been tested for the following indicators: turbidity, pH, conductivity, permanganate index, hardness, chlorides and iron. The samples were analyzed by an accredited laboratory; therefore the methods of analysis stipulated by the laws and standards in force were respected. The procedures took place at a 20 oC, ± 2 oC room temperature, as stipulated by STAS 6300/1998 and a humidity ratio of less than 65%. In order to determine the turbidity levels, the samples were analyzed congruent to SR EN ISO 7027/2001, using a stationary LP 2000 turbidimeter with a microprocessor provided with a tank and a tank cover. The turbidimeter’s precision is ±0.5 FTU at a 20 oC temperature. The pH level was determined by the analysis method stipulated by SR ISO 10523/2009, using a laboratory pH meter – ThermoFisher Scientific Orion 3-Star, made in USA. The pH meter is provided with a temperature adjustment device and with a thermometer readable to 0.5oC. The pH measurement accuracy is 0.01 units.

The electronic conductivity was determined using the analysis method stipulated by SR EN 27888/97, using a laboratory conductivity meter - ThermoFisher Scientific Orion 3-Star, made in USA. The device has a relative accuracy of 3.5% of the average readings and is provided with a ±0.1oC relative accuracy thermometer.

The permanganate index is determined by using the analysis method congruent to SR EN ISO 8467/2001. The following devices were used: Radvag AS 220/C/2 analytical balance (Poland);

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WSC/4D Hamilton-Glass double distillation cabinet still, made in UK and a TW 20 Julabo water bath, made in Germany. The water bath is provided with a rack that holds the 100 mm test tubes; it ensures a quick temperature rise to 96-98 oC for all the test tubes simultaneously as well as temperature stability afterwards.

The ammonium levels are measured by the SR EN ISO 7150-1/2001 analysis methods, using the following equipment: Radvag WPS 2100/C/2 precision balance (Poland) with a load capacity of 0.5- 2100 g and second class precision; Radvag AS 220C/2 analytical balance (Poland), with a load capacity of 0.1- 2200 g and first class precision; HCH 1500 chemical hood, ElectronicApril SRL Cluj Napoca; Julabo TW 20 water bath (Germany); WSC/4D Hamilton-Glass double distillation cabinet still, made in UK; Orion 2 Star pH meter with digital display and pH triode Orion 9157 BNMD, series LQ 16371; UV-VIS Specord 50 Analitik Zena spectophotometer (Germany) with a measuring range between 190-1100 nm.

The water hardness is determined by using the EDTA titrimetric method as required by the SR ISO 6059/2008. The following devices were used: Radvag AS 220C/2 analytical balance (Poland), with a load capacity of 0.1-2200 g and first class precision; WSC/4D Hamilton-Glass double distillation cabinet still, made in UK; Orion 2 Star laboratory pH meter with a temperature adjustment device that has a 0.01 units accuracy and a pH triode, produced by ThermoFisher Scientific, USA.

The levels of chlorides in the water are measured by the Mohr method, as stipulated by SR ISO 9297/2001. The equipment used: Radwag AS 220/C/2 analytical balance (Poland) with a load capacity of 0.1- 2200 g and first class precision; HCH 1500 chemical hood, ElectronicApril SRL, Cluj Napoca.

The iron levels in the water are measured according to SR ISO 6332/1996. The following devices were used: Radvag WPS 2100/C/2 precision balance (Poland) with a load capacity of 0.5- 2100 g and second class precision; Radwag AS 220/C/2 analytical balance (Poland) with a load capacity of 0.1- 2200 g and first class precision; HCH 1500 chemical hood, ElectronicApril SRL, Cluj Napoca; Julabo TW 20 water bath (Germany); WSC/4D Hamilton-Glass double distillation cabinet still, made in UK; Orion 2 Star pH meter with digital display and Orion 9157 BNMD pH triode, series LQ 16371; UV-VIS Specord 50 Analitik Zena spectophotometer (Germany) with a measuring range between 190-1100 nm; filter funnels provided with low porosity membranes – below 0.45 µm.

For the manganese levels in the water samples an atomic absorption spectophotometer analysis method was used, as stipulated by SR 8662-2/1997. The laboratory equipment included: Radwag AS 220/C/2 analytical balance (Poland), with a load capacity of 0.1- 2200 g and first class precision; HCH 1500 chemical hood, ElectronicApril SRL, Cluj Napoca; Julabo TW 20 water bath (Germany); WSC/4D Hamilton-Glass double distillation cabinet still, made in UK; Orion 2 Star pH meter with digital display and Orion 9157 BNMD pH triode, series LQ 16371; UV-VIS Specord 50 Analitik Zena spectophotometer (Germany) with a measuring range between 190-1100 nm; Analitik Yena atomic absorption spectophotometer with a measuring range between 190-1100 nm.

RESULTS AND DISCUSSION For the reverse osmosis system presented in this paper, the above mentioned indicators were measured on a regular basis. The results are presented in tables 1, 2, 3 and 4.

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Table 1. Week 1 Parameter Source MAC values*[2,3] Reverse osmosis

first stage Reverse osmosis

second stage Manganese 53(µg/l) 50 (µg/l) BDL (µg/l) BDL (µg/l)

Iron 0.001(mg/l) 200 (µg/l) BDL (mg/l) BDL (mg/l) Ammonium 0.02(mg/l) 0,50 (mg/l) BDL (mg/l) BDL (mg/l) Turbidity 0.65(NTU) �1,00 (NTU) 0.45 (NTU) 0.28 (NTU)

pH 6.65 �6,50 �9,50 5.32 4.91

Conductivity 1944(µS/cm) <2500 (µS/cm) 64.00 (mS/cm) 31.50 (mS/cm) Permanganate index 1.34(mgO2/l) 5.00 (mgO2/l) 0.51 (mgO2/l) 2.94 (mgO2/l)

Hardness 32.9(oG) �5,00 (oG) 6.84 (oG) 4.48 (oG) Chlorides 257(mg/l) 250 (mg/l) 10.90 (mg/l) 8.79 (mg/l)

* MAC – maximum accepted concentration NTU – nephelometric turbidity units BDL – below detection limit

Table 2. Week 2 Parameter Source MAC values [2,3] Reverse osmosis


second stage Manganese 41.1 (µg/l) 50 (µg/l) BDL (µg/l) BDL (µg/l)

Iron 0.001 (mg/l) 200 (µg/l) BDL (mg/l) BDL (mg/l) Ammonium 0.02 (mg/l) 0,50 (mg/l) BDL (mg/l) BDL (mg/l) Turbidity 0.57 (NTU) �1,00 (NTU*) 0.26 (NTU) 0.27 (NTU)

pH 6.88 �6,50 �9,50 5.35 5.3

Conductivity 1961 (µS/cm) <2500 (µS/cm) 60.6 (mS/cm) 44.9 (mS/cm) Permanganate index 0.19 (mgO2/l) 5.00 (mgO2/l) 0.12 (mgO2/l) 0.96 (mgO2/l)

Hardness 32.7 (oG) �5,00 (oG) 9.64 (oG) 4.71 (oG) Chlorides 282 (mg/l) 250 (mg/l) 13.7 (mg/l) 10.7 (mg/l)



second stage Manganese 42 (µg/l) 50 (µg/l) BDL (µg/l) BDL (µg/l)


pH 7.21 �6,50 �9,50 5.71 5.54



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second stage Manganese 39 (µg/l) 50 (µg/l) BDL (µg/l) BDL (µg/l)


pH 6.18 �6,50 �9,50 5.71 5.69



By analysing the date given in the above tables it results that a number of the measured

parameters have values below the limits given by the norms. It should be emphasized that the value of a certain parameter - conductivity, which indicates

the chemical quality of water, i.e. the quantity of substances dissolved in water, is drastically reduced after passing through membranes (e.g. from 1938 µS/cm to 47.3 mS/cm at stage I, respectively 32 mS/cm at stage II).

Chlorides, i.e. the chlorine combined with other chemical elements, also indicate the chemical quality of water. In the source water they almost reach the maximum accepted concentration, or sometimes even exceed it, but after stage I the values drop to 9.4 mg/l, respectively 8.5 mg/l.

The source water is clean, organic substances are found in small quantities. This is reflected by the permanganate index or by the oxidizability of water that also indicates the chemical quality of water, the source water having values between 1.34 mgO2/l and 0.19 mgO2/l, which are below the maximum accepted limits. Nevertheless, by using the reverse osmosis process, the values dropped from 0.19 to 0.12.

CONCLUSIONS In the end we can appreciate that using the reverse osmosis in different technological processes allows for the values of different physico-chemical parameters to be adjusted in a way that can be difficult to obtain by using other methods. Using the two-stage reverse osmosis provides an increased efficiency.

REFERENCES 1. BADEA, Gheorghe (2010), Aliment�ri cu ap� (Water supply), Editura Risoprint, Cluj–Napoca,

Romania. 2. *** Legea 458 din 8 iulie 2002 privind calitatea apei potabile (Law 458/July 8th 2002 on the quality of

drinking water). *** Legea 311 pentru modificarea �i completarea Legii nr. 458/2002 privind calitatea apei potabile (Law 311 for modifying and completing Law 458/2002 on the quality of drinking water).

3. BADEA, Gheorghe (2008), Instala�ii Sanitare (Sanitary Installations), Editura Risoprint, Cluj–Napoca, Romania.

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NEEDS AND TRENDS IN THE FINANCING, BUILDING AND MANAGEMENT OF SOCIAL HOUSING

IACOBOAEA Cristina, LUCA Oana*, GAMAN Florian,

Technical University of Civil Engineering, e-mails: [email protected], * [email protected] (corresponding adress), [email protected]

A B S T R A C T The building and management of social housing is an important activity in the EU Member States and societies are interested in dedicating time and financial resources to this activity. When we compare the wide and rich definition of social housing in EU Member States, the management imposed for this objective of building and maintaining social housing to the one stipulated in the Romanian Housing Law it becomes obvious that we need to adapt the existing public funding increase trends to the level of the central and local government and stimulate them to build and manage social housing under the extended scope of its definition.

Keywords: social housing, social impacts, financing, management


INTRODUCTION In some countries social housing means a type of housing that ensures a minimum level of

comfort for the people using it and is built with funds provided by the state or drawn by it for this purpose. Such social housing is intended for groups of low income individuals and is generally represented by flats situated in high apartment buildings at the periphery of cities with significant malfunctions in the supply of utilities and public services or with limitations when it comes to public transportation and job opportunities. From its very definition, social housing appears like a building of doubtful qualities and its inhabitants seem to be deprived of the benefits of urban life and socially, communicationally and economically segregated. The more time lapses over the elements of the building, the deeper this image gets; this image also contributes to the occurrence and maintenance of serious social tensions and segregation, to a decreased security level and to the decay of the neighbourhood. MATERIALS AND METHODS

To study the status quo of social housing in Romania in all its aspects one needs to tackle the various elements of contents of its definition – generically speaking – from the viewpoint of European regulations since the EU Member States understand this issue differently. We refer to the fact that the latter take into account the stakeholders taking part in the building of the social housing projects (beneficiaries, sponsors, organisers, constructors etc.) which are different from one Member State to the next when it comes to the economic, historic and financial peculiarities and to the responsibility for their development, strategy and management. It is to be noted that a series of criteria common to all EU Member States must be taken into consideration for the comprehensive definition of the concept of social housing, i.e. [2]:

a) the allocation and access criterion (definition of target groups and of the allocation procedures plus the set of sub-criteria and secondary criteria established by the government and enforceable by the local authorities based on a set of local priorities and minimum check-ups);

b) the accessibility criterion (such as low prices or low rents for low income groups);

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c) security of tenants/owners (long term rental contracts and security for the owners from the social sector area).

Such criteria apply to all social housing which can also be identified in other forms of

property such as: - social residences that may be rented (managed by the local or central authorities) which

may also include the ones intended for vulnerable groups such as boarding schools, university campuses, homes for the elderly and so on;

- private residences resulted from the privatisation of the public residences of countries in transition (whose owners cannot invest in the maintenance of the buildings);

- private residences built with the substantial help of the authorities (housing for average income groups).

All these categories are covered by the definition provided by CEDODHAS (European

federation of social, cooperative and public housing) in 1998: social housing is “housing where the access is controlled by the existence of allocation rules favouring households that have difficulties in finding accommodation in the market“. This definition being very general, it leaves out the aspects of tenure and refers to target groups only in general terms. This may lead to inconsistencies in the way it is interpreted in different countries [2].

In Romania, social housing is defined in the Housing Law no. 114/1996 which defines it as “the residence rented for a subsidised rent to individuals or families whose economic situation does not allow them access to a residence of their own or to rent a residence in the usual market terms.”

The beneficiaries of such housing are representatives of groups of people who have lost their homes either because of restitutions or because of being poor and not being able to pay the costs for certain operations related to the residence (mortgage, fictitious sales papers) and, last but not least, people who are part of a nomadic population settled at the outskirts of cities, in insufficiently managed areas.

If we add to these groups those whose “stay” is limited, such as students, non-resident pupils, old people without any support, socially assisted people with disabilities whose families support them insufficiently and who are a significant proportion of the no-income population we get a general image of the necessary number of social residences. The sheer acknowledgement of the status quo is not enough; it entails a series of responsibilities to develop a coherent policy adapted to the stakeholders, the financial sources and the local regulations on the use of the built areas.

There are similarities in the way in which the issue of social housing is approached from all its sides concerning the stakeholders in most of the European countries. In order to find a solution, first of all with much less waste of human energy is needed; the first prerequisite is the involvement of the most important stakeholders, i.e. the funding providers from the public and private sector under the coordination of the local public administration whose capacity to unite everybody involved allows them to cover the social housing needs.

For instance, in Berlin a series of apartment buildings is being transformed into a small village for Roma families. Rather than scatter them discreetly in a series of small projects, they are being housed in one large complex in the suburb of Neukoelln.

The idea is to provide homes for people who have been excluded and discriminated, proving they can be integrated into society. The main financing source came from catholic charity which decided to take over the apartment block because it was in an unsatisfactory state [3].

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The efficiency of such projects increases with the economic strength of a country which also brings a clearer and better definition of stakeholder responsibilities and a more efficient management.

Thus, the social housing issue becomes an ordinary activity of the local administration especially since the number of requests is low enough due to the living standards of the majority of the population which are high enough to cover the need for a house and eliminate the need of social support.

In Romania the economic and social transition stages pushed housing prices to unreachable levels for those with low incomes whose number increases as years pass by. Thus, the houses owned by the local councils for rental purposes are fewer in numbers and they become insufficient compared to the growing demand [4].

The most recent data from December 2009 show that in Romania there were 193,378 registered state-owned residences, i.e. 2.36% of the total number of residences [5]. This low percentage is due on the one hand to the selling by the state to its tenants of the rented residences occupied until 1990 and on the other hand to the shy involvement of the state in the building of housing after 1990. If until 1989 state participation to the financing, building and distribution of social housing exceeded 90%, after 1990 its contribution dropped to less than 10%.

The use and maintenance of social housing is largely influenced and determined by their inhabitants who may contribute to the proper maintenance of the buildings and increase their quality or, on the contrary, to their decay. Here, a decisive role is played by the level of education. A lack of adaptability to collective housing in apartment buildings and a low education level have led to the decay of the social housing apartment blocks and to the evacuation of the owners. Most of the times they were not given another residence and they had to live illegally in disadvantaged areas and insalubrious conditions [6].

Table 1. Program of state-owned dwellings built between 2001 and 2010 [7]

Number of dwellings reported as finished No. Name of program Year

2001 Year 2002

Year 2003

Year 2004

Year 2005

Year 2009

Year 2010

1. Housing for young people for renting purposes 106 2,096 4,937 4,272 3,435 3222 7500

2. Social housing as per the Housing Law no. 114/1996 441 139 247 94 190 1.225 250

3. Social housing for tenants evicted from the nationalised houses - - - - - 1,259 507

The table above does not break down the types of social housing but includes all social houses owned by the state before the Law no. 114/1996 from the following categories:

- Residences from the state-owned pool of residences which were not sold during the privatisation period begun in the ‘90s; many of them have better functional parameters than social residences and may be sold;

- Nationalised residences occupied by the tenants but not returned to the former owners; here, the former are likely to become potential applicants for social housing.

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Thus it becomes obvious that the public sector needs to continue building, distributing and managing social housing depending on the financial sources available from the local and national budget.

RESULTS AND DISCUSSIONS

The procedure needed to get a social housing space must be complied with by anyone and this procedure means following certain steps. The individual who wishes to apply for social housing goes to the Town Hall of the town where s/he has his/her permanent residence. Based on the hierarchy of priorities, according to the fundamental criteria of the law, the Local Council may approve through a Decision a residence with the characteristics of a social residence, within the limits of the available resources; thus, the right provided by law becomes effective ones it is determined that there is an available residence or maybe there are funds to subsidize the rent, for instance.

The fact that the private sector does not take part in the financing of social housing has a negative impact on their number and it also violates the right of the poor to get a house. This situation is a consequence of the economy of our country, where the private sector could not develop stable economic activities which would allow it to participate to the financing, building and distribution/renting of social housing below the market price.

The low participation of the private sector has its sporadic manifestations in real-estate donations. The attempts to give credits to the groups of people with average income were successful but they were limited due to the status of the national economy which cut the budgets so that the issue of social housing was postponed for the future. The weak stability of the economy does not encourage the private sector to finance professional residences to reduce the need for social housing. Usually they prefer to rent from the existing residences at the market price or to shy away from the responsibility of providing their employees with a place to live.

Neither did the NGO sector nor the private funds which participated to this process get to that level of development allowing them to make social housing investments; therefore for the following categories of residences the only funds available remain the state managed public funds:

- residences built through the National Housing Agency for young people whose income level is lower than the one needed to purchase a house or to rent as per the market terms;

- social residences destined to tenants evicted from the residences returned to their former owners as per Law 51/2006 (the Law approving the Government Emergency Ordinance no. 68/2009 regarding the activity development measures in the field of housing construction through national programs) or 84/2008 (the Law approving the Government Emergency Ordinance no. 74/2007 which ensures the social housing fund for evicted or soon-to-be evicted tenants from the houses returned to their former owners ) as amended;

- residences built through the National Investments Company (CNI-SA) to accommodate individuals evicted from the residences which need to be strengthened through the Program for the Reduction of the Seismic Risk in the case of Multi-storey Residential Buildings.

Such programs did not help the poor but did manage to cut the total number of applications

for social housing, thus facilitating the exertion of their right to a residence; however, applicants have also become the prisoners of political logos without any security in their perspective to get a social residence. If we put these programs together with the ones needed to build and maintain the temporary residences (boarding schools, campuses, homes for the elderly) which are managed by state structures but which also waste public funds, we see a dilution of the responsibility to create

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social housing which leads us to conclude that the Housing Law needs to be recast and enriched with new provisions. They should refer in particular to the balancing out of the building and rehabilitation process for social housing with the level of public funds available through a coherent urban development policy which should have a certain prioritisation in relation to its social envelope.

CONCLUSIONS

There are clear differences between the definition of social housing in the EU countries and its definition in Romania; therefore we suggest that the Romanian legislation should also take over the new trends:

1. Enlargement and diversification of the social housing concept so as to cover notions related to all forms of housing subsidizing.

2. Provision of economic facilities for stakeholders (public, private, NGO, inhabitants, other stakeholders) in order to create a pool of social residences which is quality-wise and quantity-wise adequate for low income individuals.

3. Increased preoccupation to avoid the social and spatial segregation of communities, to avoid the formation of disadvantaged areas and for this purpose:

- Residences designed for low income individuals should be built everywhere in the city in order to favour social mixing; large scale operations leading to concentrations of such residences in one place should be avoided;

- The value of the state aid should differ depending on the income (sometimes it should subsidize the entire amount) and not on the degree of comfort in the residences;

- Considerable efforts should be made to offset the small surface of apartments from the areas with large social housing projects built in the previous years with an increased comfort provided by a careful landscaping (green areas, pedestrian areas, parks, playgrounds etc.)

- The current and future needs of social housing in terms of size must also take into account the structural changes in Romania related to the ageing of the population and the evolution of the marriage and divorce phenomena which lead to an increase in the number of households with just one member and of single parent families.

4. The need for a better economic efficiency of social housing investments achievable through the adoption of constructive solutions in line with the concept of sustainable development and through the use of the newest projects/technologies/materials which can insure low operation prices and low energy consumption.

5. The adoption of an efficient social housing management, considering the number of homeless people and of those with seasonal social housing based on a computer application.

6. The inclusion of boarding schools, elderly homes and campuses buildings in the definition of social housing; all of these are living spaces with a strong social component and dedicated to disadvantaged groups who do not have enough money to rent.

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REFERENCES 1. *** (2003), UN Economic Commission for Europe (2003), Workshop on social housing Prague. 2. *** (1996), Romanian Housing Law no. 114/1996, republished, with further amendments and

completions. 3. Der Spiegel (2012), http://www.spiegel.de/international/germany/village-in-romania-makes-exodus-to-

troubled-berlin-neighborhood-a-825933.html, 04/06/12, viewed in July 2012. 4. VOICU, B. and NOICA, R. (2003), Nevoia de locuin�e în Romania (The need of housing in Romania),

Institutul de Cercetare a Calit� ii Vie ii/ Research Institute for the Quality of Life Bucharest. 5. Statistical yearbook (2010), section Dwellings and public utilities, Romania. 6. IACOBOAEA, Cristina (2009), Slums in Romania - Case study - Residential quarter located on the

outskirts of Bucharest city. Metalurgia International 14 (8), p. 245-248, ISSN 1582-2214. 7. *** http://www.mdrt.ro/lucrari-publice/programe-de-constructii-de-locuinte, viewed in May 2012.

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MULTIPATH EFFECT MITIGATION IN SIGNAL PROPAGATION THROUGH AN INDOOR ENVIRONMENT

IONA�CU Anamaria,

Technical University of Civil Engineering Bucharest, e-mail: [email protected]

A B S T R A C T Highly accurate positioning of an object is a target that requires measurements performed with devices (mainly Global Navigation Satellite System receivers) able to provide a satellite connection towards minimum four satellites. However, GNSS receivers face low accuracy in areas where the satellite signals are obstructed or even non-existent. In order to obtain location estimate in an Indoor environment, a series of Indoor Positioning Systems based on WLAN technology and pseudolites have been developed. Signal propagation in an Indoor environment is affected by several factors, among them the multipath effect, cause by reflective surfaces around the receiver. This paper aims at analyzing different methods for mitigating the multipath intereference on signal propagation.

Keywords: GNSS, Pseudolites, WLAN Positioning Systems, Indoor environments, reflection, refraction


INTRODUCTION For being a Line-of-Sight (LOS) system, a Global Navigation Satellite System is not suitable

for navigation in environments where the satellite signals are obstructed, due to the fact that in order to calculate the precise position of an object, the positioning system must be equipped with a device which ensures a satellite link. Or, it is known the fact that in Indoor areas, the satellite signals are blocked and even the most expensive GNSS receivers will not function properly in order to provide high accuracy. In urbanised Indoor environments and beyond, the Line-of-Sight condition towards minimum four satellites can not be accomplished by a GNSS receiver. Satellites are able to sense visible light, infrared radiation and other electromagnetic radiation, therefore the transmitted signals are in the visible spectrum, which means that they will penetrate through clouds, glass, plastic, but they will be easily obstructed by most solid objects such as walls, buildings, mountains, trees etc.

Whereas GNSS works well in many Outdoor scenarios, it suffers from obstacles such as skyscrapers creating shielded street canyons (or urban canyons) or walls blocking the radio signal. Furthermore, Indoor environments causes a series of problems to the propagation of GNSS signals, such as the multipath effect, interference, attenuation, near-far effect, no-line-of-sight (NLOS), Indoor path loss. The same errors occur when deploying a WLAN Positioning System in an Indoor environment, the WLAN signal propagation being highly attenuated in the presence of surrounding objects.

Multipath (or signal reflections) is the effect of transmitted signals who arrive at the receiver’s antenna on different paths in addition to the direct signal, when they encounter a reflective or a separation surface between two environments.

Multipath signals are delayed with respect to the direct signal and the amplitude, phase and polarisation, and it is characterised by the reflective surface and the number of reflections [1].

(Fig. 1) shows a phasor diagram describing the carrier tracking loop operation and demonstrating a relationship between in-phase (I) and quadrature (Q), with the direct (Ad) and reflected signal (Am), together with their combined signal (Ac) [2].

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Fig.1. Phasor diagram MATERIALS AND METHODS 1. Multipath effect

The signal propagation, whether transmitted by a WLAN Access Point or by GNSS satellites, is highly affected by the multipath interference to the extent that multipath signals can interfere destructively with the direct signal, which will be faded. The multipath problem severity varies with the environment where the measurements are taken. Therefore, an Indoor environment causes more reflections and diffractions on the signal propagation due to the fact that there is a wide range of reflective objects, such as reinforced concrete, metallic structures, furniture etc. The multipath propagation refers to signal reflection on flat, reflective surfaces close to the MD’s antenna. The radio signal travels over a distance and is either reflected by a nearby surface, arriving at the MD’s antenna by two or more paths in addition to the direct signal, or is absorbed by surrounding objects such as walls and floors, as seen in (fig. 2).

Fig.2. Multipath propagation

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The location estimate is influenced by the localization scenario and the radio propagation in Indoor environments would also suffer from multipath fading. The Radio Frequency based positioning systems performances depend mostly on the electromagnetic characteristics of the environment which can suddenly change due to the some factors existing in the Indoor environment. Thus, the presence of walls and other structures, persons, furniture, open/closed doors will obstruct the direct path of radio signals, producing a decrease in accuracy of estimated location in Indoor environments.

However, the performance from the accuracy point of view is not acceptable for several Indoor location based applications. Phenomena like multipath intereference, reflections and refractions can provide different amplitudes and phases on the end receiver. The combination of these replicas of the transmitted signal can be either constructive either destructive through the generation of a random and sudden fluctuation of the received power strength [3].

2. Experiments and discussion

After an analysis of WLAN signal propagation on several Test Points (TP4, TP11) in the experimental test bed, it was concluded that, although the RSSIs have a constant behaviour in time with only ±5 [dBm] variations, the propagation is still affected by the multipath effect, as seen in (fig. 3), (fig. 4). An offset of +10 [dBm] and more is produced by the reflection and refraction from surrounding objects.

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Fig. 3. RSSI samples recorded in TP4 with H=1.00m Satellite signals propagation inside a building is 20÷30 [dB] weaker than in Outdoor

environments. The range between the receiver and the GNSS satellite is dependent on the propagation time needed by the signal to reach the receiver. The receiver’s time scale is not synchronised with the GNSS satellites time scale, due to high implementation costs of atomic clocks in GNSS satellites, which is not feasible for a regular receiver. The distance measured to at least four satellites is obtained by means of multiplying the signal propagation time by the speed of light in order to get 3D position estimation, and it is called pseudorange due to errors that appear in the time measured. Errors in pseudorange measurements of tens of meters results from the multipath effect.�

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Fig. 4. RSSI samples recorded in RP11

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Fig. 5. Spectrum analyzer In (fig. 5) a spectrum analyzer of signal propagation transmitted by the pseudolites from a

Integrated Pseudolites/GNSS System is presented, with visible multipath signals.

3. Multipath Mitigation methods There are several approaches to mitigate the multipath propagation such as antenna based

methods and signal processing methods. 3.1. Antenna based methods

Sensitivity to RHCP and Axial Ratio: When reflected, the transmitted GNSS signal changes its polarisation into left-hand, unlike a direct signal. The GNSS antenna is designed to have high sensitivity to the right-hand circular polarised signals (RHCP – co-polar signals) and low signals for

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the left-hand polarised signal (LHCP – cross-polar signals) [4]. A RHCP antenna is small in size, does not need extra signal processing hardware in the receiver, and suppresses the LHCP signals partially, therefore it is not able to mitigate effectively multiple reflected signals. The quality of a Circular Polarised antenna is measured by the ratio of co-polar to cross-polar components recorded by the antenna, identified by means of the Axial Ratio (AR) parameter. A good performance antenna should have an AR parameter close to 1dB in broadside, increasing with decreases in elevation angles, while a high performance antenna should have an AR parameter ranging between 3 to 6 dB with an elevation angle of 10 degrees.

Choke ring ground plane antenna: The choke ring ground plane antenna is used to mitigate the low elevation angle reflected signals in the antenna by reducing its gain at low elevation angles and creating a high-impedance surface which prevents propagation of surface waves near the antenna. This method is effective in mitigating low elevation reflected signals, by reducing code and carrier phase multipath errors[5]. The use of a choke ring ground plane antenna has limitations concerning big size and weight, and in dynamic applications where the altitude of the antenna is not fixed causes the elimination of low elevation direct signal when the ground plan is not horizontal.

Antenna array: A directional antenna consists of a series of antenna elements combined in an array, in order to be able to have gain in one direction and loss in another direction. An antenna array can distinguish between the multipath signals and the direct one by adding spatial dimension. The combination of applied relative amplitude and phase shift on each antenna elements is reffered to as the complex weight [6]. The correct weight is applied to each element of antenna array by means of signal processing techniques. A directional antenna is big in size and needs additional signal processing techniques. However, it provides a good control of the antenna pattern and ensures the mitigation of multipath signals. 3.2. Signal processing methods

Narrow early-late correlator: The Narrow early-late correlator method is effective for long delay secondary path and it is not able to track the signal in low Signal to Noise Ratio situations. A chip difference smaller than 1 (usually 0.1) is used in the code discriminator between the early and the late code. The relative delay of the secondary path must be of at least 300 meters (one chip) for the C/A code. The phase multipath error is similar to the wide correlator due to the fact that it depends on the shape of the signal autocorrelation function which is the same for both wide and narrow correlators.

Double delta correlator family: Within this method two correlator pairs are used in the code discriminator function and includes several code multipath error mitigation techniques, such as the High Resolution Correlator (HRC) and the Early/Late Slope technique. The Double delta correlator family method can mitigate medium delay multipath effect on carrier phase measurements, showing a better performance than the Narrow early-late correlator. This technique does not perform well on short (less than 30 meters) and long delay multipath signals.

Maximum Likelihood based mitigation method: The parameters of the direct signal are determined together with the multipath signals that minimise the mean square error between the received signal and the estimated signal. Even though the computational burden and algorithm implementation costs are high, the Maximum Likelihood estimation is the most efficient method to mitigate the multipath effect, the code and carrier multipath errors being greatly reduced [7].

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CONCLUSIONS When implementing a Pseudolite/GNSS integrated system for location estimate, the Indoor

environment is notorious for multipath propagation and noise. In GNSS receivers the signal arrives at a very low or even a negative elevation angle becoming subject to signal fading. They manifest as severe signal power fluctuations, and lead to signal loss. The problem can be solved by using spatial separation of the antennas and by using pulsed signal and double frequency to overcome any environment generated noise.

The multipath signals are delayed in relation to the direct signal due to the fact that the amplitude, carrier phase and polarization are different, featured by the reflective surface and the number of reflected signals, hence the reflected signal will always be longer than the direct signal. Short delay multipath usually has a greater impact on pseudoranges than long delay multipath, hence its effects are difficult to mitigate due to the fact that reflective objects from close proximity of the antenna corrupts the correlation function peak. If the delay is large enough, the receiver is able to mitigate the multipath effect due to the fact that it does not affect autocorrelation function peak, hence the positioning algorithm is able to track the correlation between the reflected signal and the direct signal.

However, Indoor environments are considered to be the most suitable areas where multipath signals are actually useful for a GNSS receiver or a WNIC, since there is little or no direct GNSS or WLAN signal strength inside buildings. Whereas the variety of signals resulting from the direct signal taking different paths over a range of angles enhances the possibility of the signal to be received by the antenna, the multipath propagation is used in order to increase the capacity of the channel the signal is transmitting in (e.g. Multiple-Input and Multiple-Output (MIMO) technology).

REFERENCES 1. BILICH, A. (2012), Introduction to Multipath: Why is multipath such a problem for GNSS?,

http://www.gpsworld.com/tech-talk-blog/introduction-multipath-why-multipath-such-a-problem-gnss-11328, 19 January 2008, viewed at 30/07/2012.

2. IONA�CU, A. (2012), Parametrii care influen�eaz� intensitatea semnalului WLAN la propagarea într-un mediu Indoor (Factors which Influences the RSSI Propagation in an Indoor Environment), Buletin �tiin ific – Doctoral, UTCB, Nr. 2/2012, pp. 162-169, Bucharest; http://buletinstiintific.utcb.ro/ro /arhiva2012.html, viewed at 31/07/2012.

3. MONTI, C., MALVOLTI, F., RONCHINI, R., SAITTO, A., VALLETTA, D. (2009), Indoor Localization System based on Wireless Sensor Networks, Proceedings of the 5th IEEE International Conference on Mobile Ad-hoc and Sensor Systems, Vol. 7133.

4. BRENNEMAN, M., MORTON, J., YANG., C., van GRAAS, F. (2007), Mitigation of GPS Multipath Using Polarization and Spatial Diversities, Proceedings of the 20th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2007), PP. 1221-1229, Fort Worth, TX, USA, 25-28 September.

5. RAY, J. K. (1999), Use of Multiple Antennas to Mitigate Carrier Phase Multipath in Reference Stations, Proceedings of the 12th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS 1999), pp. 269-280, Nashville, TN, USA, 14-17 September.

6. LU, C. Y., ZHANG, Y., WU, J., COOK, P., LI, X., AMIN, M. (2008), Antenna Array Beam forming Technology: Enabling Superior Aeronautical Communication Link Performance, Proceedings of the International Telemetering Conference, San Diego, CA, USA, October.

7. YEDUKONDALU, K., SARMA, A. D., SRINIVAS, V. S. (2011), Estimation and Mitigation of GPS Multipath Interference Using Adaptive Filtering, Progress in Electromagnetics Research M, Vol. 21, pp. 149-161; http://www.jpier.org/PIERM/pierm21/10.11080811.pdf, viewed at 30/07/2012.

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3D SPATIAL DATA ACQUISITION AND MODELING OF ANGHEL SALIGNY MONUMENT USING TERRESTRIAL LASER SCANNING

JOCEA Andreea Florina,

Technical University of Civil Engineering of Bucharest, e-mail: [email protected]

A B S T R A C T The 3D digital documentation of architectural objects and sites becomes more and more significant in the field of 3D modeling, where the visual quality and precise measuring have a great importance. In this paper are used the technological possibilities offered by measuring technique - terrestrial laser scanning and computer graphic software - for data acquisition as well as handling the acquired data. In the first part of the paper will be presented some basic principles and operational aspects involved in the application of terrestrial laser scanning technique. In the second part of the paper are presented the 3D modeling issues from which was generated a precise and accurate 3D model of Anghel Saligny monument placed in the courtyard of the Technical University of Civil Engineering from Bucharest, Romania.

Keywords: measuring techniques, visual quality, modeling

Received: July 24, 2012 Accepted: July 31, 2012 Revised: September 07, 2012 Available online: October 31, 2012

INTRODUCTION Over time surveying instruments has suffered a major transformation due to the progress in

electronics and primarily due to the microchip development. The theodolite, the steel tape and the field book have been, in many cases, replaced by electronic field instrumentation such as EDM (Electronic Distance Measurement), GPS (Global Positioning System) and 3D laser scanning.

Each technique came with something new: the EDM has introduced “the electronically horizontal distance”, GPS has introduced “vector” and at present 3D laser scanning, which is an advanced technology that is based on the latest laser techniques for distance measurement, generates a new set of information called as “point cloud”.

While the laser technology for distance measurement is on the market for several years, the emergence of terrestrial 3D laser scanning systems grew over the last years. Until now, a classification of these systems has been realized taking into account the distance measuring principle, in geodetic applications imposing the continuous wave principle and phase difference principle. There are, also, special scanners for near field (up to 2 m) which are based on triangulation principle. Also, in order to compare different products of terrestrial 3D laser scanning it should be considered some aspects related to technical specifications such as resolution expressed as number of points/steradian, spot size of laser beam and scan rate expressed in measurement number/second.

Terrestrial laser scanning is a technique which allows the determination of geometry of a structure completely automated (more or less) without a reflective environment, with high accuracies and high speed. The space object is swept by laser beam on columns or lines, the resulting points forming in their entirety a so-called “point cloud” [Figure 1].

Terrestrial laser scanners are sensors that allow the registration of 3D position of objects by measuring a horizontal and vertical angle and a spatial distance to each point. By using trigonometric functions can be obtained the points coordinates in an internal coordinate system of

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laser scanner. These coordinates can be transformed by georeferencing in a proper (X, Y, Z) coordinate system.

Fig. 1. Terrestrial laser scanning principle [4]

The advantages of this survey procedure are the high speed and the high point density. Due to these abilities it is possible to be applied in various fields such as: archaeology, architecture and cultural heritage.

Taking into account what was have mentioned above, terrestrial laser scanning is a suitable and efficient technique for recording geometrical 3D object recording of complex objects such as monuments.

In this paper we it will be presented the geometrical 3D object recording and modeling of Anghel Saligny monument placed in the courtyard of Technical University of Civil Engineering of Bucharest, Romania [Figure 2]. The 3D spatial data acquired using Leica ScanStation 2 Terrestrial Laser Scanner was processed using Cyclone and Geomagic Studio software. Main issues pursued in this application were the degree of automation in data acquisition, data processing and the final result – object modeling.

Fig. 2. Anghel Saligny monument location

MATERIALS AND METHODS 1. Data acquisition

Before starting the scanning process, three reflective targets were placed near the area of interest, Anghel Saligny monument [Figure 3].

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Fig. 3. The area of interest and the reflective targets Data acquisition was carried out in a local scanner system. The entire structure was scanned

from 3 scan stations in one hour and 45 minutes. The scanning was performed with an accuracy of 3 mm. A total of 5.5 million scanned points were stored in a file of 184 Mb [Figure 4].

Fig. 4. The area of interest and data acquiring scan stations

2. Data processing

The data processing was carried out in the first step with Cyclone software, then with Geomagic Studio software. The first step in data processing was the transformation of all point clouds from the local scanner system into a common system (so-called registration process). This step was achieved in Cyclone software using a 3D Helmert transformation (7 parameters) without taking into account the scale factor. The scanning and registration operations were performed automatically using reflective targets. The targets were recognized semi-automatically by the program during the scanning process.

The registration process was realized without inconveniences due to the fact that we had only 3 scan stations and the targets were correctly acquired during scanning process. Thereby a precision of 1 mm was obtained [Figure 5].

Fig. 5. Registration process result

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The second step of processing was the generation of the virtual 3D model. For this the registered point cloud was filtered and consequently the volume of data was reduced [Figure 6].

Fig. 6. a.The registered point cloud; b. The filtered point cloud

3. Modeling

The raw data supplied by the laser scanner systems are not always well suitable for a direct use in CAD systems. After the cleaning of the 3D point set, a simple and more direct way to produce a surface, that can be sufficient for some applications, is to generate a polygon mesh. A polygonal mesh is described by topology and geometry. The topology of the mesh is given by the neighborhood structure and the geometry is defined by the coordinates of the vertices. The topological structure of the mesh contains vertices, edges, triangles and other features like holes, genus and number of connected components. The relation between these elements is given by the Euler-Poincare formula:

V-E+F-H=2(C-G) (1)

where V is the number of vertices, E the number of edges, F the number of triangles, H the number of holes, C the number of connected components and G the sum of the geni of all components [2].

The simplest type of polygon meshes, currently used in most of the commercial scanning or reverse engineering software, is the triangular mesh. This type of mesh is usually generated using the Delaunay triangulation method [5].

The geometrical dual of the Delaunay triangulation is the Voronoi diagram [Figure 7]. It essentially divides the space into convex cells by creating a region around each known site pi such that every point � from the region is closer to the point p than to any from the other sites [5]. The topological elements of the Voronoi diagram are: the Voronoi point (the point located at equidistant distance from three different sites), the Voronoi line (given by the points which are equidistant to two sites in the plane) and the Voronoi cell or polygon [1].

a. b.

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Fig. 7. Delanay triangulation vs. Voronoi diagram [1]

In order to process the polygonal mesh by producing the final model of Anghel Saligny

monument, a set of procedures should be performed to detect and fix topological or geometrical defects, to remove unwanted or unnecessary data and to create a complete mesh [Figure 8], [1]. These operations were carried out automatically in Geomagic Studio software. Although the statue case is not very complicated to carry out the task, in the present case study were used almost all the above software applications.

Fig. 8. Topological and geometrical errors

After performing the automatic computation of the triangle meshing, the result was optimized

afterwards, the existing holes were filled and the surfaces were smoothed. The final result is presented in Figure 9.

Fig. 9. The optimized result

During the smoothing of the surfaces one had to proceed very carefully in Geomagic Studio,

since important details and intricacies of the surface are quickly lost by overregulation of the parameter settings. Generally while handling this dataset with Geomagic Studio it was revealed that

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experience was necessary for optimal parameter control [3]. A geometrically correct 3D model of the monument [Figure 10] has been generated by processing of the complex object areas (free form surfaces) with Geomagic Studio, which demonstrates a very high visual recognition value [3].

Fig. 10. The final result – Anghel Saligny Monument

CONCLUSIONS

This paper describes the use of terrestrial laser scanning as main procedure of data acquisition in field of cultural heritage. The practical example demonstrates that the tested terrestrial laser scanner system (Leica ScanStation 2) is suitable for detailed data acquisition and object modeling providing high qualitative data. REFERENCES 1. DU�ESCU E. (2006), Digital 3D documentation of cultural heritage sites based on terrestrial laser

scanning, PhD Thesis, Germany, pp. 58-59. 2. KARBACHER S. & CAMPAGNA S. (2000), Principles of 3D Image Analysis and Synthesis, B.Girod,

G. Greiner und H. Niemann (Ed.), Kluwere Academic Publishers, Boston – Dordrecht-London, pp. 141-143. 3. KERSTEN T.P. (2010), 3D scanning and modeling of the Bismarck monument by terrestrial laser

scanning for integration into a 3D city modeling of Hamburg, M. Ioanides (Ed.):Euromed 2010, LNCS 6436, pp. 179-192, 2010, Springer-Verlag Berlin Heidelberg.

4. NEUNER J. (2009), Sensors Course Note, Technical University of Civil Engineering of Bucharest, Faculty of Geodesy, Romania.

5. PREAPARATA F.P & SHAMOS M. I. (1985), Computational geometry: an introduction. Springer-Verlag.

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THE STUDY OF BOND STRENGTH AND BOND DURABILITY OF HIGH PERFORMANCE CONCRETE

MOLDOVAN Radu*, M�GUREANU Cornelia, CAZAN Oana

Technical University of Cluj-Napoca, *e-mail: [email protected] (corresponding adress)

A B S T R A C T This paper will present an experimental program that analyzes bond behavior in aggressive environments. Dimensions of High Performance Concrete specimens are 100 mm by 100 mm, with a 10 mm size bar inserted in the center. Curing treatment consisted of three stages: first, all specimens were submerged in water for 28 days. At this age aproximately one third of the specimens were tested for bond charactersitics. Second, the remaining specimens are half introduced in the aggressive environment (3% NaCl solution similar to sea water) and third, half are cured in nominal conditions (t = 20°C ± 2°C, RH = 60% ± 5%). The specimens kept in NaCl solution are tested at two different ages: 90 and 180 days, followed by the comparisons between the bond strength at aggressive environmental samples from the nominal environment.

Keywords: bond, high performance concrete, aggressive environment, durability

Received: August 01, 2012 Accepted: August 07, 2012 Revised: September 13, 2012 Available online: October 31, 2012

INTRODUCTION Previous research has been carried out on the durability of high strength concrete with regard

to the influence of aggressive environment on concrete durability. Research investigations have been conducted on the effects of 3% NaCl solution, on compressive strength, tensile strength and bond strength of high strength concrete. Only for a w/c ratio lower than 0.28 the concrete seems to resist to chemical attack. Durability of concrete is controlled in large by his permeability. Because high-strength concrete has a dense matrice, it has a very low porosity, compared with normal concrete. MATERIALS AND METHODS 1. Behaviour of bond

The stress acting parallel to the bar along the interface is called bond stress. Steel to concrete bond is the phenomenon which allows longitudinal forces to be transferred from the reinforcement to the surrounding concrete in a reinforced concrete structure. Steel strains differ from concrete strains, a relative displacement between the steel and the concrete (slip) does occur, but this lack of compliance is also the effect of the highly-localized strains in the concrete layer closest to the reinforcement (interface) [1].

Theoretical and experimental studies conducted to explain the mechanism of steel to concrete bond have shown that the bond resistance is made up of three phenomenons: chemical adhesion, friction and mechanical interlock between the bar and surrounding concrete. For plain bars, only the first two of these components contribute to the bond strength. For deformed bars, the surface protrusions or ribs interlocking with and bearing against the concrete key formed between the ribs contribute more positively to bond strength, and is the major reason for their superior bond effectiveness [2] (see Fig. 1).

For uniform bond, the bond stress can be expressed as:

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dbb ld

F⋅⋅

=π

τ (1)

where: F = pullout force; db = diameter of the bar; and ld is the embedded bar length.

Fig. 1. Strains between two ribs of deformed bars [2]

where: �i= adhesion strain;

�c= compressive stress under deformation of the rebar; �f= friction strain between two ribs.

2. Concrete mixture

For the tests a high performance concrete with strength class C80/95 was used. During the casting, the fresh concrete properties were evaluated using the slump test (23cm) and by determining the fresh concrete density (2460Kg/m3).

Table 1. Concrete mix design Mixture Quantity

Cement 520,00 kg/m³ Microsilica 52,00 kg/m³ Superplasticiser 15,60 l/m³ Water 133.2 l/m³ Fine aggregate(river sand) 771,50 kg/m³ Crushed gravel(4-8 mm) 257.67 kg/m³ Crushed gravel(8-16 mm) 686.31 Kg/m3

w/cm 0,26

3. Experimental program Experimental program analyzes the behaviour of high strength concrete bonding found in

unfavorable environmental conditions. Aggressive environment used is a solution of NaCl, with concentration 3%, similar to sea water. Casting the necessary specimens was made in three different days, and the concrete was prepared in the Central Laboratory of Civil Engineering in Cluj. Curing treatment consisted of three different methods:

- Curing method A: curing for 28 days under water at t = 20°C ± 2°C. - Curing method B: curing for 28 days under water, then in our climatic chamber at

t = 20°C ± 2°C, RH = 60% ± 5%. - Curing method C: curing for 28 days under water, then introduced in the aggressive

environment, 3% NaCl solution [4],[5]. The specimens cured in method A, were tested at 28 days for mechanical and bond

characteristics. The specimens cured in method B and C, were tested at two different ages, 90 and

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180 days, followed by the comparisons between the mechanical and bond strength at aggressive environmental samples from the nominal environment (t = 20°C ± 2°C, RH = 60% ± 5%). For each of the three ages of testing were casted 12 samples: 6 in which reinforcement is parallel to the direction of casting and 6 in which reinforcement is perpendicular to the direction of concrete casting (see Fig. 2).

The compressive and tensile strength tests were carried out in accordance with RILEM (1994) [6]. The testing procedures can be seen in Fig.3 and Fig.4.

Fig.2. Preparing the bond specimens

Fig.3. Compressive strength Fig.4. Tensile strength 3.1. Pull-out specimen fabrication

For the pull-out bond test, dimensions of High Performance Concrete specimens are 100 mm by 100 mm, with a 10 mm size bar of high strength steel (fyk = 500MPa) inserted in the center and the embedded bar length is ld = 5ds, (see Fig 5). Due to the disruptive efforts generated by end zone conditions of the specimen, during testing, in the lower part of the specimen, bond between steel and the embedded bar is prevented by using a PVC tube over a length equal to 5ds [6].

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Fig.5. Details of the test specimens

3.2. Pull-out test

The pullout test specimens were loaded by the hydraulic machine, which has maximum loading 40 tons (400 kN). The specimen is placed vertically on the bearing plate, provided with a central 2ds cavity, of the traction device. The tension force (F) is applied, at the lower extremity (the longer one), while the apparatus for measuring the displacement (�) is placed at the upper extremity of the bar. The specimen is loaded progressively up to bond failure, the splitting of the concrete cube or steel rupture failure, hence the relation between tensile force (F) and displacement (�).

)(∆= fF (2)

The loading rate vp = F/t must be determined for each bar diameter in order that the rate of increase of the bond stress be constant (RILEM,1994). The bond behaviour under monotonic loading of pull-out specimen was tested on RILEM type specimens.

Fig.6. Pull-out test Fig.7. Splitting of the concrete cub

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RESULTS AND DISCUSSIONS Table 2 presents the test results for the compressive strength (fcm) and tensile strength (fct,sp)

using the curing methods A, B and C. Compressive strength increases with age, but notice that the compressive strength values of

normal specimens are almost the same as the compressive strength of the specimens kept in aggressive solution, which points out that 3% NaCl solution does not influence compressive strength of high strength concrete.

Using curing method C, the tensile strength decreased about 3% when compared with curing method B.

Table 2. Properties of hardened concrete using curing method A,B and C

t0=28days t0+90days t0+180days Material properties A B C B C

fcm (MPa) 128.74 133.15 134.2 134.8 135.35 fct,sp (MPa) 6.38 - 6.69 6.24 6.03

Table 3 presents the bond stress for the specimens using curing methods A, B and C. Observe at age of 28+90 days, for the casting position parallel face to reinforcing bar, a

decrease in bond strength by 1-2% of the specimens kept in corrosive environment towards those specimens in normal conditions, while at 28+180 days the bond strength of specimens cured in method C decreased 3% when compared with method B. For the specimens where the casting position is perpendicular face to reinforcing bar, at age of 28+90 days, �0.01 of the specimens cured in method C decreased 35% when compared with method B.

Table 3. Bond stress � (MPa) using

curing methods A,B and C t0=28days t0+90days t0+180days A B C B C

�0.01�

(MPa) 24.93 16.73 16.34 19.20 18.75

32.47

30.22 30.13

30.12 29.96

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(MPa) �(mm) 0.05 0.036 0.04 �0.01

(MPa) - 12.80 8.23 - -

-

33.56

33.08 34.17

34.10 ��

(MPa) �(mm) 0.068 0.212 0.028

where: �0.01=bond strength for a 0.01mm slip (�=0.01mm);

�max= maximum bond strength; �= slip between steel and concrete.

In all these cases, the bond failure occurred before displacements reached 0.1mm.

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CONCLUSIONS Following these investigations it was shown that high-strength concrete behaves very well to

chemical attacks due to texture and toughness, hence resistances obtained on specimens cured in chemical environment for 90 and 180 days showed small or insignificant decreases for compressive strength.

In case of bond strength, it presents a small decrease at the age of 90 days, if the specimens were kept in corrosive solution. The research is to be continued by studying the influences of the same 3% NaCl solution over a longer period of time.

ACKNOWLEDGMENTS

This paper was supported by the project „Improvement of the doctoral studies quality in engineering science for development of the knowledge based society-QDOC” contract no. POSDRU/107/1.5/S/78534, project co-funded by the European Social Fund through the Sectorial Operational Program Human Resources 2007-2013.

REFERENCES 1. *** (2000), CEB-FIB 2000, Bond of reinforcement in concrete, Bulletin 10. 2. ONE� T. (1982), Beton armat (Reinforced concrete), Bucure�ti, pp 40-43. 3. M�GUREANU C. (2003), Betoane de înalt� rezisten�� i performan�� (The high strength concrete), Ed.

UT Pres, ISBN: 973-662-013-1. 4. M�GUREANU C. et al. (2005), Influence of aggressive environmental effects on the high strength/high

performance concrete. SP-228/96, Seventh International Symposium on the Unitilization of High-strength/High-Performance Concrete, American Concrete Institute, pp.1509-1513.

5. NEGRU�IU C. (2010), Durability of High Strength and High Performance Concrete, Ph.D. Thesis, Technical University of Cluj-Napoca, Romania.

6. RILEM (1994), Technical recommandations for the testing and use of construction materials, E&FN Spoon.

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RECYCLED AGGREGATES AND RIGID PAVEMENT ENGINEERING

MUSCALU Marius-Teodor*, RADU Andrei, BUDESCU Mihai, ��RANU Nicolae,

Technical University “Gheorghe Asachi” of Iasi, e-mails: * [email protected] (corresponding adress), [email protected], [email protected], [email protected]

A B S T R A C T The paper presents laboratory research activities undertaken to evaluate and improve the influence of recycled aggregates (RA) on the mechanical behaviour of roller compacted concrete (RCC) rigid pavements. To meet the proposed objectives, the research program developed innovative technical solutions aiming to improve the physico-mechanical characteristics of RA, namely Los Angeles, microDeval and impact wear coefficients, mixture density homogeneity and mixture contamination. Also, the mechanical properties of hardened RCC prismatic and cylindrical test specimens manufactured with natural/recycled aggregates have been investigated. Performed laboratory analysis on RCC test specimens refer to four point bending strength, compressive strength of prisms ends/cylinders and modulus of elasticity of cylinders.

Keywords: demolished cement concrete, roller compacted concrete, performance improvement technologies, laboratory analysis.


INTRODUCTION RA presents a viable alternative for replacing natural aggregates (NA) in different

construction works. Inferior mechanical performances of conventional RA often leads, in the most optimist case, to the use in low value construction elements. To confer improved performance characteristics to RA, the research developed technologies and application methodologies, suitable for RA mixtures, following the conventional recycling techniques of demolished concrete. To evaluate the contribution on the characteristics of RA particles, a comparison between the mechanical characteristics of original and new RA is performed. Also, the influence of RA on the mechanical behaviour of RCC cylindrical and prismatic test specimens has been investigated.

MATERIALS AND METHODS

The research aims to identify difficulties and to evaluate the influence of using recycled aggregates on the behaviour of RCC rigid pavements. Performed experimental tests and the resulting conclusions are based on laboratory level analysis. Full scale construction and adequate exploitation monitoring of experimental sectors [1, 2] are relevant and important research stages to confirm that RA manufactured RCC pavements are a viable, durable and environment friendly alternative to conventional rigid pavements.

Inferior performance characteristics of RA in comparison with those of NA represent the main issue in the decision process of the material type usage in different construction works [3]. It is well known that RA particles present higher wear coefficients and water absorption then the NA particles [4] used to the manufacturing of the recycled concrete. Same principle is valid even in comparison with most of NA types found in the economic environment, due to the presence of mortar on the RA particles. Other difficulties refer to the lack of control regarding the density homogeneity of RA particles due to concomitant recycling of different concrete elements types, or contamination of RA mixtures with other materials present in the demolition process such as wood, plastic, ceramic, glass or others. For RA to represent a viable solution for replacing NA used in the pavement construction, strategies to gain rigorous control of the mechanical characteristics of RA

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need to be developed. The investigated RA are obtained by recycling of cement concrete resulted in the demolition process of industrial buildings in Iasi municipality [5]. The crushing process of the demolished cement concrete has been achieved using a jaw crusher after which, a separation procedure of the resulting RA mixture into 0-4, 4-8, 8-16 and 16-25 mm particle size classes, has been performed.

Table 1 presents, in comparison, the main physico-mechanical characteristics of resulted RA [5] and of NA (chippings) used in the manufacturing of RCC test specimens.

Table 1. Performance characteristics of investigated RA and NA Aggregate type Mechanical characteristic Aggregate particle size

class RA NA (chippings) Activity coefficient 0-4 [mm] 1.04 [%] 1.62 [%]

4-8 [mm] 24.25 [%] 14.3 [%] Los Angeles wear coefficient 8-16 [mm] 26.01 [%] 11.2 [%]

microDeval wear coefficient 10-14 [mm] 18.80 [%] 8.28 [%] Impact wear coefficient 8-12.5 [mm] 19.80 [%] 9.20 [%]

4-8 [mm] 81.86 [%] 100 [%] Crushing coefficient 8-16 [mm] 80.75 [%] 100 [%] 4-8 [mm] 2.2163 [Mg/m3] 2.827 [Mg/m3] Dry state density

8-16 [mm] 2.3034 [Mg/m3] 2.836 [Mg/m3] 4-8 [mm] 2.3427 [Mg/m3] 2.881 [Mg/m3] Saturated state density

8-16 [mm] 2.4035 [Mg/m3] 2.882 [Mg/m3] 4-8 [mm] 5.70 [%] 1.80 [%] Absorption coefficient

8-16 [mm] 4.34 [%] 1.70 [%]

As expected, studied RA present increased wear coefficients and water absorption and lower crushing coefficient and density compared with conventional NA (chippings) used in pavement engineering.

For RA to compete with NA in high value construction works, strategies aiming to improve the common resulted mechanical characteristics of RA need to be considered. This can be achieved either by creating new recycling technologies which lead directly to the obtaining of improved performance RA, or indirectly, by developing additional technologies to the existing recycling techniques which improve the original characteristics of RA.

To obtain RA with improved performance characteristics, the research program developed laboratory tested technologies applicable on RA aiming to lower the wear coefficients, to control the density homogeneity of RA particles and to remove the RA mixtures main contaminants. The principles and benefits of the developed technologies are summarily detailed in the next three chapters.

The next step of the research is the manufacturing of RCC test specimens using only NA, for reference performance tests, and mixture of natural and recycled aggregates to evaluate the influence of RA on the strength behaviour of hardened RCC. Chapter 4 presents the laboratory test results and methodology of the investigation regarding the use of RA to the manufacturing of RCC pavements.

1. The pre-wear process of RA

The developed technology [6] aims to improve the RA particles weak edges and surfaces resulted in the crushing process of broken cement concrete. As illustrated in figure 1, weak edges and surfaces of RA particles are formed where rupture planes of recycling concrete intersect the old mortar. Also, in figure 1, particles on which the studied procedure has been applied, are presented.

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Fig.1. Illustration of original RA particle and improved RA particle The aim of the technology is to induce a wear state to the old mortar attached to RA particles.

The objective has been achieved by concomitant mixing of RA and metallic cubes using standard Los Angeles testing equipment (free fall mixing), as shown in figure 2.

Fig.2. Laboratory methodology for the application of the developed technical solution (a – original RA; b – metallic cubes; c – Los Angeles testing equipment; d – new RA mixture)

After performing the described procedure, a new sorting of the resulting RA mixture may be

required. Two mixing periods (60 sec and 120 sec) have been adopted to evaluate the yield of the process on the performance characteristics of the improved RA. Table 2 presents the results of tests performed on new RA particles in comparison with those of original RA regarding the Los Angeles, microDeval and impact wear coefficients.

Table 2. Wear coefficients of original/new RA RA type Mixing period Los Angeles wear

coefficient microDEVAL wear

coefficient Impact wear

coefficient original 8-16 [mm] 0 [sec] 26.0 [%] 17.9 [%] 19.8 [%] new 8-16 [mm] 60 [sec] 22.4 [%] 16.0 [%] 14.3 [%] new 8-16 [mm] 120 [sec] 21.0 [%] 14.6 [%] 13.0 [%]

As expected, the new RA particles durability has been considerable improved with direct

influence on the wear coefficients characteristics, even in the case of mixing for 60 seconds. Also, other benefits have been identified such as limitation of the initial micro cracked state of the constructed concrete elements, slight increase of the particles density and lowering of the water absorption coefficient due to partial removal of old mortar from RA particles.

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2. Density homogeneity control of RA particles One inconvenient in considering RA as replacement of NA in different construction works is

the uncertain density homogeneity of RA particles. Variability in density of RA occurs when different types of broken cement concrete (e.g. lightweight, 1.8÷2.0 Mg/m3, and conventional, 2.4÷2.6 Mg/m3) are processed and recycled simultaneous. This difficulty is often met on demolition sites due to lack of building design documents which can help develop complex recycling strategies.

To overcome this difficulty, the research program developed a laboratory procedure and testing equipment [7] aiming to evaluate the density homogeneity of particles from a RA mixture. As shown in figure 3, the testing equipment is formed from two chambers (pressure chamber and RA specimen chamber) separated by a screen. The equipment containing the RA test specimen is then placed on a vibratory table and connected to few air compressed sources.

Fig.3. Developed laboratory testing equipment and methodology for density homogeneity check If the particles contained by the specimen mixture present high variability in density, at the

end of the test, lightweight particles should be found on top of the mixture and heavier particles on the bottom. Figure 4 presents the particles distribution during a performed test in both initial and final stage. Due to lack of lightweight RA particles, the test has been carried out on a mixture of studied RA particles (density of 2.2÷2.3 Mg/m3) and crushed bricks particles (density of 1.8÷1.9 Mg/m3).

Fig.4. Particles density homogeneity test (a – initial stage of test; b – final stage of test)

RA

chamber

Pressure

chamber

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The performed test highlights the utility of the procedure in determining the density homogeneity degree of a RA stockpile which can help the decision for the use in high value construction works.

3. The RA mixture decontamination process

To prevent the contamination of RA mixtures, it is recommended to remove from the site the other present materials [8] such as wood, metal, bricks, ceramic, plastic or others, before the demolition process of the cement concrete is performed. Also, the transfer and stock of broken cement concrete and RA need to be performed taking into consideration adequate measures.

The colour sorting methodology, used mainly in the food industry for the separation of different quality of seeds, rice, cereals, beans, nuts etc., as shown in figure 5a [9], could represent a viable option for removal of RA main contaminants. The principle, as described in figure 5b [10], is to reject particles which present a different colour then the admissible colour range of the machine setup.

Fig.5. Colour sorting methodology (a) [9] and equipment principle (b) [10] Same process and equipment can be adapted for the decontamination of RA, with reduced

supplementary research costs due to existing advanced technology and technical experience in food industry.

4. Study of the behaviour of RCC test specimens manufactured with RA

To evaluate the influence of RA on the mechanical behaviour of RCC, prismatic and cylindrical test specimens have been manufactures using 100% NA, for reference results, and 60%/40% mix of NA and RA respectively. As mixture binder, the research program used three different types of cementitious and hydraulic binders, namely CEM I 42.5R, CEM II BM S-LL 32.5R and DOROPORT TB 25.

For achieving maximum compaction degree of the RCC test specimens, modified Proctor test has been performed for both 100% NA and 60%/40% NA/RA compositions of RCC variants, the results being presented in table 3.

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Table 3. Modified Proctor test results for optimum moisture content of RCC variants

Mixture moisture content, [%] Aggregate type RCC mixture

Mixture density characteristic 5 6 7 8 9 10 Wet, [Mg/m3] 2.271 2.310 2.338 2.322 - - 100% NA

0% RA Dry, [Mg/m3] 2.141 2.156 2.171 2.167 - - Wet, [Mg/m3] 2.063 2.077 2.100 2.136 2.150 2.142 60% NA

40% RA Dry, [Mg/m3] 1.930 1.933 1.938 1.950 1.957 1.942 For each RCC variant, three cylinders and three prismatic specimens have been manufactured

(figure 6a) and tested (figure 6b) for the evaluation of the modulus of elasticity of cylinders, prisms four point bending strength and compressive strength of cylinders/prism ends.

Fig.6. Manufacturing (a) and testing (b) of RCC specimens The results of the performed test, at different hardening age, for the evaluation of the

mechanical behaviour of different RCC variants are presented in table 4.

Table 4. Results of mechanical behaviour tests of prismatic and cylindrical RCC specimens

Compressive strength, [MPa] Variant

no.

AN/AR ratio,

[%/%]

Binder type

Binder dosage, [kg/m3]

Testing age,

[days] Cylinders Prism ends

Bending strength,

[MPa]

Elasticity modulus, [MPa]

a 100/0 28 11.78 24.31 4.09 18,300 b 60/40

300 28 8.28 9.79 1.96 17,678 1

c 60/40

CEM I 42.5R

300 28 11.29 19.34 3.65 18,258 a 100/0 28 17.57 23.46 5.05 24,352 2 b 60/40

CEM II 32.5R 300

28 16.70 21.15 4.01 23,449 a 100/0 250 28 9.61 14.88 3.52 13,268 b 100/0 250 42 10.52 17.16 3.76 18,241 c 100/0 350 28 13.07 17.28 3.91 19,577 d 100/0 350 42 15,27 19.53 4.10 20,334 e 60/40 300 28 10.84 16.81 2.92 17,362

3

f 60/40

Doroport TB 25

300 42 12.08 18.72 3.42 18,273

DISCUSSIONS The approach for developing new technologies aiming to confer improved performance

characteristics of RA mixtures represents a viable economic and durable solution. RA could be used to the construction of high value concrete elements influencing the recycling rate of demolished cement concrete and leading to the protection of the environment and human health [11].

Regarding the test results presented in table 4, as can be noticed, after testing the specimens manufactured in 1a and 1b RCC variants, the reduction in compression and bending strength of the

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hardened RA RCC has been found varying from 20% to an incredible 50%. With the assumption that RA manufactured RCC maybe needs a different approach compared with conventional RCC, the research focused on the preparation stage of the fresh mix. The used methodology for the mixing stage of the fresh RCC 1a and 1b variant composition has been performed as follows:

- step 1: insertion in the mixer of the corresponding dosages of 4-8mm and 8-16mm NA/RA particle size classes;

- step 2: addition of water for partial hydration of particles; - step 3: mixing for a period of 20sec; - step 4: adding the remaining corresponding dosage of 0-4mm NA/RA particle size classes

and the binder dosage; - step 5: mixing for a period of 2min from which in the first 60sec the remaining water

necessary for mixture hydration has been continuously added. Assuming that the main difference between NA and NA/RA manufactured RCC is the

presence of old mortar in the RA particles, and that the hydration procedure from the second step in de mixing methodology prevents the formation of adequate bond between the mortar surface and the new RCC matrix, the research proposed to modify the second from the conventional mixing procedure to meet the mentioned presumptions, as follows: addition of mixture of water and a small quantity from the necessary dosage of the used binder, for partial hydration of particles.

As expected, the performance test results of the 1c RCC variant register improved mechanical behaviour compared with 1b RCC variant, but reduced in comparison with 1a RCC variant by only 5 to 15%. Figure 7 illustrates how the modified mixing procedure helps covering the RA particles leading to improvement of the bond between old mortar and the new RCC matrix.

Fig.7. Illustration of bond strength between RA particles and RCC new matrix After confirmation of the described phenomenon, variants 2 and 3 of RCC have been

manufactured using the modified mixing procedure.

CONCLUSIONS The research program developed three innovative technical solutions, applicable on RA

mixtures, aiming to confer better control of the performance characteristics. The technologies help on the improvement of RA particles wear coefficients, evaluation of the density homogeneity and decontamination of RA mixtures leading to the extension of the field of use for RA to high value construction works.

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Results of laboratory tests performed on hardened RCC specimens show that inferior types of binders (e.g. CEM II BM S-LL 23.5R and DOROPORT TB 25) are more suitable for use to the manufacturing of RCC pavements due to the dry state of the mixture which cannot support to fully hydrate high performance cementitious binders.

The paper highlights that, when dealing with RA in the production process of RCC, several tests and analysis must be performed in order to determine the best mixing methodology of component materials to confer highest mechanical performance to hardened concrete.

Replacement of 40% NA in the production of RCC with investigated RA leads to the reduction of compressive and bending strengths by 5-15% with no influence of the modulus of elasticity.

ACKNOWLEDGMENTS

This paper was supported by the project "Development and support of multidisciplinary postdoctoral programs in major technical areas of national strategy of Research - Development - Innovation" 4D-POSTDOC, contract no. POSDRU/89/1.5/S/52603, project co-funded by the European Social Found through Sectorial Operational Program Human Resources Development 2007-2013.

REFERENCES 1. MUSCALU, M.T. (2008), Accelerated load testing of rigid structures under simulated traffic,

Proceedings of the sixth International Symposium Transportation Infrastructures New Developments, Highway and Bridge Engineering 2008, 12 December, Iasi, Romania, pp. 255-266.

2. Varlan, T., Zbarnea, C., Bulau Camelia and Muscalu, M.T. (2010), Realizarea pe raza D.R.D.P. Ia�i a unor structuri rutiere din beton de ciment compactat cu cilindrul compactor, armat dispers cu fibre de o�el provenite din reciclarea anvelopelor (Construction on D.R.D.P. Iasi activity area of roller compacted concrete pavement structures disperse reinforced with recycled fibers derived from tire recycling), Al XIII-lea Congres National de Drumuri �i Poduri / XIIIth National Roads and Bridge Congress, 15-17 September, Poiana Brasov, Romania.

3. MUSCALU, M.T. and TARANU, N. (2010), Use of recycled materials in pavement construction, International Symposium Technology and innovation in transportation infrastructure, Highway and Bridge Engineering 2010,10 December, Iasi, Romania, pp. 15-21.

4. HANSEN, T.C. (1992), Recycling of Demolished Concrete and Masonry, Report of Technical Committee 37-DRC, RILEM Report 6.

5. MUSCALU, M.T. and RADU, A. (2011), Use of Recycled Aggregates in Rigid Pavement Construction, The Bulletin of the Polytechnic Institute of Jassy, Construction Architecture Section, Published by Technical University “Gheorghe Asachi” of Iasi, LVII (LXI) Tome, Fascicule 2, pp. 69–78.

6. MUSCALU, M.T. (2012), Metod� pentru îmbun�t��irea unor performan�e ale agregatelor reciclate prin aplicarea unei uzuri (Method for improvement of some performances of recycled aggregates by application of a wear), Cerere de brevetare OSIM nr A/00356 din 21.05.2012 / Innovation request OSIM no A/00356 from 21.05.2012.

7. MUSCALU, M.T. (2012), Dispozitiv de laborator pentru evaluarea omogenit��ii densit��ii agregatelor reciclate (Laboratory equipment for the evaluation of the density homogeneity of recycled aggregates), Cerere de brevetare OSIM nr A/00426 din 13.06.2012 / Innovation request OSIM no A/00426 from 13.06.2012.

8. Potera� G. (2006), Reciclarea materialelor provenite din demol�ri �i dezafect�ri (Recycling of materials derived from demolitions and decommissions), revista Salubritatea / Salubritatea magazine no 1 (17).

9. *** http://www.grainsorter.net, viewed at 15.03.2012. 10. *** http://www.satake.com.au, http://www.satake.com.au/colour_sorting/index.htm, viewed at

16.03.2012. 11. *** Directive 2008/98/EC of the European Parliament and of the Council on waste, 19 November.

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THE VALORISATION OF HISTORICAL SITES THROUGH ARCHITECTURAL INTERVENTIONS

NARI�A Alina-Maria*, MO�OARC� Marius,

“Politehnica” University of Timisoara, e-mails: * [email protected] (corresponding adress), [email protected]

A B S T R A C T The issue of preserving the historical and natural heritage is usually sealed with the interdiction to do any sort of intervention that might compromise its values. Nevertheless, intrinsic threats and risk factors like weather phenomena, carelessness or unsustainable tourism have caused and will continue to cause damage when only conservation and renovation interventions are permitted. Such cases require a different protection strategy that should result from a close study based on the evolution of the present historical area and of other similar ones. As architects and engineers we continuously ask ourselfes what should we do to protect them and how to revitalize and emphasize the cultural values of our heritage.

Keywords: heritage, historical site, architectural intervention, cultural background

Received: July 31, 2012 Accepted: August 08, 2012 Revised: September 19, 2012 Available online: October 31, 2012

INTRODUCTION Imbued with a message from the past, the historic monuments of generations of people

remain to the present day as living witnesses of their age-old traditions [1]. Nowadays, Romania is taking small steps towards the valorisation of its rich cultural heritage.

However, the future of the romanian historical and natural sites remains uncertain due to the lack of interest and education of its citizens and due to financial and political matters. In most cases, buildings now classified as monuments that were not integrated in an urban landscape became ruins because they had been abandoned and robbed afterwards.

The law does not provide enough protection for historic buildings and sites and as a consequence, interest in their preservation and revitalisation disappeared. For example, the ancient capital of the Dacian Kingdom, Sarmizegetusa is not valued as it should be although it became part of the World International Heritage in 1999 on the basis of the following criteria:

- The Dacian Fortresses represent the fusion of techniques and concepts of military architecture from inside and outside the classical world to create a unique style.

- The Geto-Dacian Kingdoms of the late 1st millennium BC attained an exceptionally high cultural and socio-economic level, and this is symbolized by this group of fortresses.

- The hill-fort and its evolved successor, the oppidum, were characteristic of the Late Iron Age in Europe, and the Dacian Fortresses are outstanding examples of this type of defended site [2].

Currently, the archaeological area is facing interventions that have caused damage: in 2011,

the local authorities have permitted the construction of a asphalt roadway that crossed the site destroying the ancient walls [3]. And most recently, we are confronted with the possibility of loosing the protection offered by UNESCO and the right to be registered on the World Heritage List [4]. The questions raised are: how to prevent the factors that threaten Romania’s cultural heritage and what kind of interventions should be enforced in order to promote and highlight the importance of our country’s archaeological sites.

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MATERIALS AND METHODS According to the Venice Charter of 1964 the concept of historic monument embraces not

only the single architectural work but also the urban or rural setting in which is found the evidence of a particular civilisation, a significant development or a historic event [1].

Today, many such areas are being threthened, phisically degraded, damaged and even destroyed by the impact of the urban development. As a consequence, ICOMOS (The International Council of Monuments and Sites) drew up in 1987 an international charter for historic towns and urban areas: the Washington Charter that defines the priciples, objectives and methods necessary for the conservaton of historic towns and urban areas.

1. ICOMOS guidelines

As specified in the Washington Charter, Section Principles and objectives: • „Qualities to be preserved include the historic character of the town or urban area and all

those material and spiritual elements that express this character, especially: a) urban patterns as defined by lots and streets; b) bonds established between the urban patterns and the green and open spaces surrounding

them; c) the formal appearance, interior and exterior, of buildings as defined by scale, size,

construction, style, materials, colour and decoration; d) the relationship between the town or urban area and its surrounding setting, both natural

and man-made; and e) the various functions that the town or urban area has acquired over time.

• Planning for the conservation of historic towns and urban areas should be preceded by

multidisciplinary studies. Conservation plans must adress all relevant factors including archaeology, history, architecture, techniques, sociology and economics and should also aim at ensuring a harmonious relationship between the historic urban areas and the town as a whole.

• New functions and activities should be compatible with the character of the historic town or urban area; adaptation of these areas to contemporary life requires the careful installation or improvement of public service facilities.

• When it is necessary to construct new buildings or adapt existing ones, the existing spatial layout should be respected, especially in terms of scale and lot size. The insertion of new and contemporary interventions compatible to the surroundings should be encouraged since such features can contribute to the enrichment of an area.

• Knowdledge of the history of a historic town or urban area should be expanded through archeological investigation and appropriate preservation of archeological findings.

• Historic towns should be protected against natural disasters and nuisances such as pollution and vibrations in order to safeguard the heritage and for the security and well-being of the residents. Preventative and repair measures must be adapted to their specific character.

• The participation and the involvment of the residents are essential for the success of the conservation programme and should be encouraged. In order to do so, a general information programme should be set up for them, beginning with children of school age.

• Traffic inside a historic town or urban area must be controlled and parking areas must be planned so that they do not damage the historic fabric or its enviroment.

• When urban or regional planning provides for the construction of major motorways, they must not penetrate a historic town or area, but they should improve access to them” [5].

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2. Current examples of architectural interventions on historic sites The last decades have been characterized by the growth of a cultural debate on the issue of

archeological site preservation and valorisation. As time went by, different solutions were adopted according to the needs of active or passive conservation. Therefore, in some cases, objects have been removed from the original place they were found, and placed in museums or galleries.

Nowadays we try to apply methods of in situ preservation so that archaeological information could be kept intact and undivided in its original context. In order to do so, engineers and architects turned to innovative technologies and materials so that needs of protection, preservation, improvement of ruins and public use could be satisfied. 2.1. The use of trasparent covers in the in situ conservation process

The choice of using a trasperent cover should be determined after carefully considering aspects from different points of view. From an architectural point of view, the cover needs to be required and realised according to criteria of restoration. At the same time, from a structural point of view, it has to ensure safety conditions minimizing physical contact between the designed components and ancient constructions. And phisically, it needs to to exclude the technical solutions that might develop a microclimate condition which could generate harmful conditions to the finds. In this field, coverings are classified by type of protected area:

- by shelter (without vertical closure) - the case of Juval Castle; - confined (with vertical closure) - the case of the ruins of the Roman Limes Gate in Dalkingen; - underground (under public spaces or basements) – the cover of the ruins at Placa de l’Almoina

from Valencia. At Juval, the cover formally takes the characteristics of the ancient roof, but made of glass,

ensuring the recognition of the intervention. The cover is protecting the old walls from collapsing and makes the covered space inside usefull for an exibition of sculptures. Here, the specialists chose a laminated glass cover equipped with an inner sheet with slight color to control the solar radiations. The cover does not completely close the inside space, providing a natural ventilation and an apropriate microclimate (Fig.1a).

At Dalkingen (Fig.1b), the cover consists of a laminated glass box that ensures a permanent transverse ventilation inside. This is achieved by a circumferencial ventilation shaft at the bottom of the glass box and by glass ventilation dampers along the gable edge of the south facade. The inclination of the roof helps dissipate the hot air at its highest point so that no heat is acumulated inside. The indoor temperature at a 2 meter height is allways lower than the outdoor temperature with aproximately 3 degrees.

Fig.1. Trasparent covers

a. Juval Castle (source: http://www.bergmeister.eu/,viewed at 23/07/2012); b.The Roman Limes Gate in Dalkingen (source: http://wikigogo.org/ru/9873/, viewed at 23/07/2012)

a b

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At Valencia the archeological material from the underground is protected by a laminated glass coverage that minimizes the UV radiation and offers support for a slim water surface. In order to avoid condensation problems under the glass coverage, the temperature of the water coating is maintained higher than the outdoor temperature [6]. 2.2. Architectural intervention in the ancient roman center of the city Merida

The project retrieves the environment of the Temple of Diana which was the forum or the city center in Roman times (Fig.2). The challenge of acting in a place with such historical and archaeological relevance has meant to work with the existing trace since the beginning, so that the finished work would recover this space from Roman times through modern language.

The project is solved with a perimeter piece L-shaped, with its own syntax, sewing its edge with the city and creating a large square around the temple. This L is the union of the platform or high walk (which at the same level of the podium liberates the archaeological level at ground floor, allowing visitors to have a new relationship with the temple) and the structural wall (which puts in Temple value by framing and abstracting it from adjacent buildings). Between the perimeter L piece and the city, a volume in the form of hanging boxes occupy interstitial spaces accommodating commercial and cultural uses.

The original sacred area is recovered, respecting the Roman archaeological features that are part of the sacred space: the temple, two side ponds, the cryptoportico and the Roman wall, which are now incorporated into the plaza [7].

Fig.2. The Roman forum of Merida

(source: http://www.archdaily.com/201918/temple-of-diana-jose-maria-sanchez-garcia/,viewed at 13/07/2012)

3. Case study The idea for a Cultural and Archaeological Research Centre at Paestum, Italy came up after

studying the Archeological Site of the ancient grecian city and its surroundings (Fig.3a). The site is located at about 100 km from Naples, in a vast agricultural region and is part of a large UNESCO heritage together with The National Park of Cilento and the Archeological Site from Velia. (Fig.3b) 3.1. Short history of Paestum According to archaeological research, Paestum was founded around the year 625 b.C. and was one of Magna Grecia’s collonies from southern Italy. The development of commercial exchanges accelerated the urbanisation process, and so, between 550 and 450 b.C. they build the three famous temples (the Basilica, the Temple of Cerere and the Temple of Neptune) that can be seen today.

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Fig.3. Street Via Nettuno: a. Map of Paestum; b. Road map The city of Paestum was conquered in 273 b.C. by the romans and became Paestum Romana. During the next two centuries, the romans organised the city according to Cardo and Decumanus and built the foro, the capitolium, the anfitheater and other public buidings as well as private residences. Unfortunately for the city, the decline followed. The need for building sailing ships led to massive deforestation and progressive sedimentation in the plain. New commercial routes were established and as a concequence, Paestum had been isolated and abandoned by the citizens during the VIIIth and IXth centuries and at the same time covered in sedimentary rocks. The city was robbed and the construction materials found have been used for the construction of other buildings, for example the Dome of Salerno. The rediscovery of Paestum happened in 1752, when Carlo the IIIrd of Bourbony built the street that crosses Paestum on the direction north-south. In the XXth century the limestone layer was removed but the process of excavation and restoration had irreparable negative effects on the previous grecian layers of the site [8]. 3.2. The architectural project

Despite its cultural values, there are fewer tourists visiting Paestum than tourists who come to enjoy the seaside. There are no periodic activities related to cultural aspects except for six festivals that happen once a year. The local inhabitants work either in agriculture, either in tourist services, transforming the pherifery of the residential area in a commercial one. As a result, outside the summer season, the shops, restaurants and camping areas are all closed and the archeological site remains empty.

The need for permanent cultural activities persists and is supported by the new archeological research that acording to the PUC of town Capaccio should start after 2010. Space for research, deposits and exposition is required.

Paestum’s link to the seaside is realised through the 7 meter wide street Via Nettuno, enclosed on both sides by camping or parking areas where people must pay a fee. Pedestrian or byking trails do not exist, and the whole street looks like a corridor that does not encourage the relationship between the ancient city and the sea.

According to the same PUC, camping places found in the protection area shall be moved outside its boundaries, leaving Via Nettuno with a deserted camping place on the northern side. In order to resolve the inconveniences caused by bad management and unsustainable tourism, a revitalisation project is needed. The project should not only accomodate necessary spaces for research or cultural activities, but also offer public places that can be used by all people, including

a

b

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tourists and inhabitants that are not participating at the events. In order to do so, a public plaza is created between the building and Via Nettuno. At the same time, the plaza offers people the posibility to enjoy and admire panoramic views over the archeological site and the natural landscape that surrounds it.

The concept of the architectural project itself is inspired from the state of ruin in which we find Paestum today. The idea is materialised through five massive volumes that seem to have fallen on the ground in a aparent disorder (Fig.4). The orientation of the volumes is taken either paralell to the seashore and the streets of the residential area, either paralell to Cardo and Decumanus characteristic to the Archeological Site of Paestum.

Fig.4. Sketches of concept

Functions are mainly organised on two floors: the first floor hosts the cultural functions:

exposition areas, conference rooms, a library and a multifunctional space (Fig.5a), whereas the groundfloor contains the archeology department with deposits, workshops for students and children, a restaurant and the sleeping area (Fig.5b). For this reason, there are two main acesses in the building. One serves the first floor and is ment to be used for the participants and visitors at expositions and conferences, and the other serves for the archeology research department.

Fig.5. Plans of the building: a) First floor; b) Groundfloor The height of the volumes measures about 12 m above the ground level and does not exceed

neither the height of the entire archaeological park situated 4m above, neither the height of the military tower that overcomes them with 40 cm. The total developed area of the Cultural Centre is 5940 sqm and covers up 9,35% of the site’s surface. This percentage is visually diminuished to 5,94% because the sleeping areas are covered with green roofs.

a

b

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The building is integrated in the surroundings by means of landscape design. Ramps of earth and vegetation go up and down between and in front of the volumes in order to obtain new and interesting relations between the interior of the building and the exterior. One of the ramps is transformed into an open air amphiteatre and links the public space in front of the building to the place that offers panoramic views towards the Archeological Site of Paestum (Fig.6). Sitting on its steps, people may admire the sea and the military tower situated in Piazza del Torre di Mare.

Fig6. Transversal section

The contemporary aesthetic of the facades is inspired from the roman style in achitecture with

massive walls and small openings (Fig.7). The dimensions and arrangement of the openings relate to the ancient belief of grecian people in the mithological gods from the heaven.

Fig.7. External view of the project with

the archaeological area in the background

3.3. Structural characteristics The resisting structure of the buildings was established in accordance with the message

transmitted by the architect and the intervention rules in historical sites. In this, purpose, to avoid building often foundations, which can affect historical sites, it was chosen a structure with large openings and reduced number of foundation. With this solution it is necessary to study in depth only a few zones from the historical sites. It relieves us from studying large areas. The areas with high seismic accelerations have led to a structure of monolithic reinforced concrete, poured between the stone finishes. The concrete walls have transmitted the loads to the foundation ground through elastic isolated foundations .In order to satisfy the functional and aesthetic needs of the building, the structure is made out of 25 cm reinforced concrete walls that sustain a 17 m opening covered with a waffle slab. The intermediary floor is a 28 cm Bubbledeck slab.The external walls are covered both on the inner side and on the outer side with 25 cm light tuffo stone that is the local material used in construction. Their thickness ensures a low heat transfer from the exterior, providing cool temperatures in the hot summer days. In this way the structure has rigidity, bearing capacity,

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ductility and the stability of a structure with such openings in a seismic zone, respecting the historical values of the site. Lighting on the first floor is brought through openings in the boxed ceilling. Tubes of mat plexiglass descend from the openings and penetrate the intermediary slab providing a natural ventilation in the workshop rooms.

CONCLUSIONS

The diploma project had been created based on the knowledge gained during the years of study at the Faculty of Architecture and therefore in accordance with the guidelines of the Washington Charter.

The strategy developed respecting the ICOMOS requirements proposes an urban regeneration that manages to increase the involvment of the local community and young people through activities that are inspired from the cultural backgroud. The final result consists in an intervention that does not contrast with the surroundings, but emphasizes them.

People will be encouraged to investigate not only ancient objects and techniques, but also the events and the political and social factors that led to the crystallization of today’s society. As a consequence, their own pride and esteem rises together with the desire for respecting and protecting their cultural heritage.

ACKNOWLEDGMENTS

The authors would like to aknowledge and thank architect Dragos Bocan for his support and guidance given during the realization of the graduation thesis. We would also like to thank professor Enrico Sicignano and Salvatore Barba for their coordination during the Erasmus placement at the Universita’ degli Studi di Salerno.

REFERENCES 1. *** (2004), International charters for conservation and restoration – second edition with introduction

by Michael Petzet, edited by ICOMOS, Munchen, Germany, pp. 37. 2. *** http://whc.unesco.org/en/decisions/2630, viewed at 24/07/2012. 3. *** http://casanoastra-romania-dacia.blogspot.ro/2011/07/asfalt-peste-cetatea-dacica.html, viewed at

24/07/2012. 4. *** http://casanoastra-romania-dacia.blogspot.ro/2012/05/alba-ministrul-culturii-atentioneaza-ca.html,

viewed at 14/07/2012. 5. *** (2004), International charters for conservation and restoration, second edition with introduction by

Michael Petzet, edited by ICOMOS, Munchen, Germany, pp. 98-99. 6. *** (2012), Proceedings, Vol. IV Biological Diversity - Museum Projects & Benefits, article: On site

archaeological museums: Types of protection, Rome, pp. 149-153. 7. *** http://www.archdaily.com/201918/temple-of-diana-jose-maria-sanchez-garcia/, viewed at

13/07/2012. 8. CARPICECI, A.C. and PENINO (1989), L., Paestum oggi e 2500 anni fa (Paestum today and 2500

years ago), Matoni Publishing, Salerno, pp. 7-14.

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SERVICES PROVIDED BY THE ROMANIAN POSITIONING – ROMPOS

PUIA Mihaela Simina, National Agency of Cadastre and Land Registration, e-mail: [email protected]

A B S T R A C T Passing from GNSS positioning in post processing mode to real time positioning involves the creation of complementary positioning systems at regional, national or local level. The complementary systems provide users additional information (differential corrections) in view of obtaining real time positioning of decimetre or centimetre level. A system that includes such services is the Romanian Positioning System created by National Agency of Cadastre and Land Registration according to European Position Determination System standards, elaborated for the creation of the integrated system for such services.

Keywords: permanent station, positioning, network, user


INTRODUCTION At the basis of the Romanian Positioning System (ROMPOS) is a network of permanent

GNSS (Global Navigation Satellite Systems) stations. A GNSS permanent station has mainly three functions: detection and automatic follow up of satellites, recording, storing and automatic qualitative analysis of data and communication with the outside (beneficiaries, other permanent stations etc.).

Romania, by the National Agency of Cadastre and Land Registration and the Technical University of Constructions in Bucharest contribute to EUREF-EPN (European Reference Frame - EUREF Permanent Network) with 5 GNSS permanent stations (since 1999 and 2006) and with a station to the global network of IGS - International GNSS Service (since 1999). The coordinates of these stations are determined continuously in the System of Reference and Coordinates recommended officially by EUREF (ETRS89) and IGS (ITRF-YY). After 2004, at national level Romania, through ANCPI, has developed in rapid pace a National Network of GNSS Permanent Stations (RN-SGP), constituting an active network (measuring continuously and generating products that are useful for positioning) and thickening the 5 stations integrated in EUREF-EPN.

Based on the GNSS permanent stations installed on the country territory, RN-SGP was created, achievement aiming to reach the following objectives: creation of an active system of reference in space and time, collecting continuously satellite data by continuous positioning of satellite stations in continental and global reference systems and by continuous provision of precise time information. Other RN-SGP objectives concern: the use of satellite observations for the positioning of points in other networks of ground planimetry and altimetry control, for the positioning of points of interest in various areas (topography, cadastre, GIS, cartography), sea navigation, aerial and land, to monitor the position and speed of moving objects (vehicles, ships, plains, persons) and use of satellite observations in scientific research. MATERIALS AND METHODS 1. ROMPOS Network

The creation of regional networks of homogenous GNSS stations took place through the initiative of specialists in the institutions responsible for the surveying activity in 18 country of Central and Eastern Europe (including Romania), through the adoption of some commune

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standards, norms, methodologies and procedures, thus constituting EUPOS (European Position Determination System).

Fig. 1. EUPOS reference stations [1]

At the present, RN-SGP includes 60 stations that were coherently designed to be as uniform

as possible over the country territory. After September 2008 this network forms ROMPOS, providing for the first time, for Romania, real time, accurate positioning.

During August 2012 a new stage of RN-SGP thickening with 15 GNSS permanent stations took place, meeting the EUPOS recommendation on the number of permanent stations necessary for the surface of Romania, namely 73 such stations, their distribution over the territory being presented in figure 2. These last stations are to be introduced in ROMPOS.

The network is non-homogenous as to GPS/GNSS equipment since those come from three producers: Leica, Topcon and Ashtech.

Fig. 2. National network of existing GNSS permanent stations and the newly installed 1...15 [2]

2. General Characteristics of ROMPOS

ROMPOS is based on RN-SGP installed by ANCPI. The reference stations function permanently, providing data in real time, as well as at preset time intervals (1 hour, 24 hours).

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The reference stations are interconnected, inclusively over the borders of neighbouring states: at present ANCPI has signed collaboration protocols with similar station in Hungary and Moldavia and has collaboration perspectives with similar station in Bulgaria, Serbia and Ukraine, and such data exchange were tested. Thus will be ensured the ROMPOS services coverage on the border area.

The distance between the stations is at present of about 70 kilometres, situation achieved after the network reached the number of 74 GNSS permanent stations.

The location of the reference stations is chosen carefully to ensure the long term stability of GNSS antennas. The location and antennas are chosen as to ensure a “visibility” horizon as possible free of buildings and to avoid possible sources of interference and “multipath” effects. Using correctly calibrated antennas, the possible “multipath” effects will be reduced. The antennas procured by ANCPI after 2008 were calibrated with the best techniques available worldwide (individual absolute calibration of each antenna). Only geodetic class double frequency receivers and antennas are used at the reference stations.

The stations receive data continuously form NAVSTAR GPS satellites (all stations) and from the Russian system GLONASS (68 stations). Once the GALILEO system will become operational, the stations will use data from its satellites. The stations’ coordinates are determined with a very good accuracy (of under 1cm) in ETRS 89 (European Terrestrial Reference System 1989) by thickening GNSS stations (Bucharest, Bacau, Baia Mare, Constanta, Deva) integrated in EUREF.

The positions of reference stations antennas are regularly checked to detect eventual displacements. The malfunctions of the system, interruptions and quality flows are identified automatically in real time.

The national reference stations are compatible with the majority of other GNSS systems. The national system ensures the inter-operability with similar EUPOS.

ROMPOS is placed by ANCPI at the disposal of users by means of the National Centre of Services ROMPOS (CNSR), which ensures the monitoring of the entire network, of the software packages that are at the basis of the system, the provision of the products of post processing and real time services to the users. 3. Services Provided by ROMPOS and Their Improvement

ROMPOS includes the following types of services: - ROMPOS DGNSS – for cinematic applications in real time with a positioning accuracy

between 3 m and 0.5m. These services may be used for Geographic Information Systems, vehicle navigation, vessel monitoring, sea and aerial navigation, hydrography, public authorities support (police, firemen, ambulance), tourism etc.

- ROMPOS RTK - for cinematic applications in real time with a positioning accuracy between 50 cm and 2 cm, addressed to applications in the field of cadastre, informational systems specific to different activity fields (local administration, residence, public utility – natural gases, water, channel), disaster management, survey in constructions and engineering, scientific research, meteorology, bathymetry survey etc.

- ROMPOS GEO (Geodesic) for post processing applications has a positioning accuracy of under 2 cm, used to achieve the ground control and thickening networks, control networks for buildings countering and monitoring in time, Geographic Information Systems (SIG), geodynamics, aerial photogrammetry, laser scanning, scientific research etc.

Depending on ROMPOS services accessed by the users, the formats in which data are sent and the types of data are presented in table 1:

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Table 1. ROMPOS Products [2] Service Availability Transmission

Environment Data Format Data Type (message) Record Rate

DGNSS Real Time Internet – NTRIP* Protocol RTCM** 2.3 1, 3 1s

RTK Real Time Internet – NTRIP Protocol

RTCM 2.3 RTCM 3.0 RTCM 3.1

3, 18, 19, 22, 1004,1006,1008,1012 1s

GEO Post processing Internet – FTP, WEB

(V) RINEX GPS (G),

GPS&GLONASS (M)

C1, L1, P1, D1, L2, P2, L2C, S1, S2 Meteo: P, T, U

1s, 5s, 30s

60s * NTRIP: Networked Transport of RTCM via Internet Protocol ** RTCM: Radio Technical Commission for Maritime Services

The system of differential navigation (D-GNSS) and/or cinematic in real time (RTK Real Time Kinematic) fulfils the following main functions:

- correction of differential or/and RTK corrections from one or more GNSS receivers (permanent stations, usually);

- communication connections from receiver to computer and the other way around; - processing of primary data and generation of differential or/and RTK corrections, using the

calculus system; - sending the differential corrections generated using the internet (protocol TCP/P, HTTP); - reception of differential corrections by the GNSS mobile receivers using the internet (protocol

TCP/P, HTTP) and other systems of real time communication (GSM, GPRS etc.); - administration of sent/received data.

The post processing services are at the present provided in three days from the request. For

the provision of automatic post processing records form GNSS permanent stations, there are created interfaces with users, making this method possible. All operations done by each of the users are recorded and stored so that the system administrators may manage the provided products and have all information needed to charge the corresponding costs.

Stages necessary to access these products could be the following: - Registration in the system, filling in an on-line form and obtaining a user and access password. - Exact specification of the category of products wanted in real time or post processing. - Setting the desired way of payment. The modalities of payment for the post processing data

could involve signing a contract to this effect – the payment taking place monthly – or by using on-line (e-payment) services – using bank cards, the payment being done before taking over the desired products.

- The activation of the account of each user allows the user to access data base on the name of the user and corresponding password.

- Accessing data using web dedicated interface that was configured for this purpose by specialists CNSR. The creation of post processing data allows setting different options like: date and time span, rate of registration, GPS or GPS+GLONASS registrations, selection of one or more stations, checking the products created before downloading.

- Permission for data download according to chosen way of payment. In case of on-line payment, before data download, the e-payment service will have to check is the respective amount for the cost of the products is available. In case of positive answer, data download is allowed. In case of signing contracts with obligatory of monthly payment, the permission to download data will not be restricted. Restrictions will occur only in case of payment delay.

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- In case of monthly payment, the software application of the system will be configured to issue detailed invoices with the presentation of products downloaded during the period covered by the invoice, which will be sent to the user in view of the payment.

The software specialized in administrating networks of GNSS permanent stations have

modules that allow the creation of post-processing for different positions in the area of the network called virtual stations. The products thus created are named virtual RINEX (VRINEX). The creation of these products is done by interpolating data from the GNSS real stations of the network. Thus are obtained RINEX data from any position of the network area. Virtual RINEX products within ROMPOS system will be available after the introduction of in the system of the last 15 GNSS permanent stations installed. Also, to create Virtual RINEX data for extrapolated positions against the national network will be necessary to introduce in network solutions also data from foreign border stations. In these conditions the post-processing service for Virtual RINEX data will be available countrywide. These data will be available for a certain, preset period by specialists CNSR of passed time according to the storing space available for the servers dedicated to this purpose. Data provision will be possible after the stages mentioned above, for RINEX products.

The provision of real time services from the centre of positioning services to the users is done in great part by internet, GSM/GPRS connections. In this way, the access to these field services depends on the coverage with signal data. In areas in which internet access is not possible, due to missing connection and due to the missing coverage with signal GSM/GPRS data, real time products could be resent by radio. In these conditions, auxiliary systems may be used, to take over the differential corrections provided by the positioning systems and to resend them by radio in areas where there is no coverage with signal data. 4. Present Status of ROMPOS

For ROMPOS system, ANCPI has created www.rompos.ro web page which provides information on the system.

ROMPOS has centralized administration through a software package in view of ensuring specific services: post processing in real time, Leica GNSS Spider. Through proper configuration by the CNSR specialists of this software application is done following: monitoring and control of GNSS permanent stations included in the network, administration and archiving of data coming from these, quality and quantity analysis of data, network configuration, creation, administration and provision of specific products, administration and monitoring of system services users etc. High system security is also ensured.

Software package that administrates ROMPOS, configured by CNSR specialists, allows the quality and integrity analysis for the data from the permanent GNSS stations, generating graphics, numerical values, NOVA maps (Network Online Visualization of Accuracy), figure 3 a and b. The status of reference stations may be visualized on-line [3], offering actual information about the approximated position of permanent stations (fig. 4) and about the network.

Besides the information concerning quality of data and of permanent GNSS stations network, the software module was configured to allow on-line registration of users for real time services (RTK and DGNSS).

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Fig. 3. Analysis of quality and integrity of data from the ROMPOS GNSS permanent stations [3] (a. Situation of records from GNSS permanent stations: up left – centralization of data from GNSS permanent stations; up right – availability of records for each station, on hours and days; down left– graphics presenting the data quality on certain criteria (e.g. cycle slips); down right – data quality report b. NOVA maps: up left – representation of errors due to ionosphere in case of single base products; up right - NRTK – representation of errors due to ionosphere in case of

network products; down left – representation of errors due to troposphere in case of single base products down right – RTK - representation of errors due to troposphere in case of network products)

a

b

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RESULTS

This article aimed at presenting the existing situation and the improvements that can be brought to the services provided by ROMPOS. There were analysed the real time DGNSS and RTK services, setting the conditions necessary to extend them nationwide. The possibility of providing virtual RINEX products and improving access to post processing products and services (RINEX and VRINEX).

CONCLUSIONS

The present use of GNSS technology in Romania significantly improves activities of survey and data processing that lead to an important growth of work productivity. In this context, RN-SGP brings a remarkable plus of efficiency to topographic and geodetic activities.

Improvements to services provided by ROMPOS and before mentioned may lead to an easier access of the provided services, through on-line procurement of ROMPOS GEO products. Also, the use area will be extended: ROMPOS GEO services will be extended by the provision of virtual RINEX products and the real time products by the introduction of bordering countries in the network station solution, and by resending differential corrections in places with no data signal coverage, using auxiliary radio systems.

Fig. 4. Approximated position for each of the station and information about their equipment [3]

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ACKNOWLEDGMENTS The study included in this article is part of the scientific research report: “Concepts

concerning the modernization of services of the positioning system” belonging to the doctorate work “Contributions to the modernization of positioning services in Romania“ of PhD Mrs. Mihaela Simina F�dur (married Puia), having as scientific coordinator Mr. Prof. Univ. Dr. Ing. Johan Neuner. REFERENCES 1. *** www.eupos.hu/EUPOS-ESDB.php, viewed at 10/08/2012. 2. *** www.rompos.ro, http://www.rompos.ro/index.php?page=articole, http://www.rompos.ro/?page=pro

duse,viewed at 10/08/2012. 3. *** http://gnss.rompos.ro/spiderweb, http://gnss.rompos.ro/spiderweb/frmIndex.aspx, viewed at

09/02/2012.

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ASSESSMENT OF THE STEEL JOINTS BEHAVIOR

RADU Dorin, University of “Transilvania Brasov” Faculty of Civil Engineering, e-mail: [email protected]

A B S T R A C T When is referred to the swivel joint stiffness, stiffness designation means that between the combined elements (ex: beam - column) there is no relative rotation, regardless of the external loads level. A pin-ended joint can be considered when connected elements can rotate freely. In terms of joint strength, it is considered complete strength when the resistance is stronger than the weakest element of the connected elements, while partial resistance joints are weaker than the combined elements. These partial strength joints are calculated to convey the internal forces and not to resist the entire load bearing elements combined. A pin-ended joint does not transmit any bending moment. Considering the strength and stiffness properties of joints, lead to their three modeling: articulated, rigid, semi-rigid. Keywords: bJoints, Semi-rigid, Joints Ductility.

Received: August 01, 2012 Accepted: August 07, 2012 Revised: August 31, 2012 Available online: October 31, 2012

INTRODUCTION As long as the swivel joint stiffness is considered in the calculation, the joints can be made in

semi-rigid version, i.e. no rigid or articulated. Thus, new modeling capabilities: semi-rigid / total resistance, semi-rigid / partial resistance.

Eurocode 3 standard is considering these possibilities by introducing three modeling: simple (if pin-end), semi-continuous and continuous.

Terms of continuous, semi-continuous and Nominally pinned are defined as follows: - Continuous: the joint ensures a perfect rotation continuity between connected elements; - Semi-continuous: the joint ensures a partly rotation continuity between connected elements; - Simple: the joint interrupts the rotational continuity between connected elements. Interpretation of these types of modeling should be done in accordance with the structural

analysis type. In the case of a global elastic analysis, only the stiffness properties of joints are important for joints modeling. The semi-rigid connection is taken into account in the calculation model by means of a spring which is characterized by the elastic constant k.

When performing a rigid-plastic analysis, the main feature is the joint resistance. In all other types of analysis are important properties such as stiffness and the resistance. RESULTS AND DISCUSSIONS

In current cases of analysis of a structure is not practical separation of the joint deformability from the web panel of the column. Therefore, these deformations can be modeled by a single spring at the intersection of joint elements axes - modeling deformation behavior of a node takes into account the deformation of the panel from shear deformation of the web and rotation of the connections.

Nodes configuration should be design to resist to EdbM

,1 and EdbM

,2 bending moments, EdbN

,1

and EdbN

,2 axial forces, EdbV

,1 and EdbV

,2 share forces transmitted from the connected elements to the joint (Fig. 4.29).

The resulted share force EdwpV

, from the web panel, will be:

(1)

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( ) ( ) 2,2,1,2,1, EdcEdcEdbEdbEdwp

VVzMMV −−−= (1)

where: z is the lever arm.

In order to model a node so that it correctly reproduce the expected behaviour, the share web

panel and each connection must be modelled separately, taking into account the bending moments and axial forces of each element which interfere at the edge of the web panel (Fig. 2 and Fig. 3).

As a simplified alternative to the presented above model, a unilateral node configuration can be modelled as a single node, and configuration of a double-side node can be modelled as two separate nodes which interact with each other. Therefore, configuring a beam to column double-side node has two moment-rotation characteristics, one for the right side of the joint and the other for the left. In a bilateral beam to column node, each fixture is modelled with separate rotation points (Fig. 3), each end of the beam has a moment-rotation feature that takes into account the behaviour of the shear web panel and the influence of the correct connection.

When determining the moment resistance and rotation stiffness for each node, the possible shear web panel influence will be taken into account according with �1 and �2 coefficients, where �1 is the value of the transformation parameter � for the right side of the node and �2 is the value of the transformation parameter � for the left side of the node.

The exact values of �1 and �2, based on the values of beam bending moments EdbjM

,1, and

EdbjM

,2, , from the intersection of the elements centres of gravity lines, can be determined using the simplified model shown in Fig. 1 (b) as follows:

21

,1,,2,1≤−=β

EdbjEdbjMM

, 21

,2,,1,2≤−=β

EdbjEdbjMM

(2)

where: EdbjM

,1, is the moment at the intersection from the right hand beam and

EdbjM

,2, is the moment at the intersection from the left hand beam

(a) (b)

Fig. 1. Forces and moments acting on the joint [5] a. Values nearby the web panel; b. Values at the intersection of the elements centre lines

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Fig. 2. Forces and moments acting on the web panel at the connections

Fig. 3. Modelling the joint (1 – Node; 2 – Left Node; 3 – Right Node): Single sided and double-sided joint configuration

The transformation parameter �, puts in direct connection the web panel shear with tension and compression forces from the joint. Spring characteristic curve Mb - � which represents the joint behaviour is shown in Fig. 5c; this results from summing the joint rotation (� c) with web panel rotation (�).

Fig. 4. Definition of � - transformation parameter [5]

In case of a single sided joint, the deformability characteristic curve from column web panel

share and rotation can be transformed in a Mb – � curve through � transformation parameter (Fig. 5).

Single sided joint

bwpFV ⋅β=

where ,ZMFbb

=

Double-sided joint

11 bwpFV ⋅β=

22 bwpFV ⋅β=

where ,11

ZMFbb

= ZMFbb 22

=

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(a) (b) (c)

Fig. 5. The bending characteristic of the spring:

a. joint; b.web panel; c.spring

Since the values of the transformation parameter � can be achieved only after determining the internal efforts distribution, its accurate determination can be made only through a cycles calculation. But for practical applications, these iterative methods are difficult to use, so it is necessary to provide conservative values for �. These values vary between � = 0, (double sided joint, equal moments equal and opposite directions, Fig. 6a) to � = 2, (double sided joint, equal moments equal and identical directions, Fig. 6b).

(a) (b)

Fig. 6. Factor � limits: a. equal and opposite direction moments; b. equal and same direction moments

Nonlinear behaviour of the joints, represented by springs with a certain rotation stiffness, it is

quite difficult to use in current design practice. Therefore, the actual moment-rotation characteristic curve of the joint can be modelled without a significant loss in accuracy by an elastic - perfectly plastic characteristic curve (Fig. 7a). This representation has the advantage of being similar to the behaviour characteristic curve of the bended elements. (Fig. 7b).

(a) (b)

Fig. 7. Bilinear moment-rotation curves [8]:

a.Joint; b.Element

Legend: ----- Real characteristic M-�

____ Idealized representation Mj,Rd - design resistance moment

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There are neglected the effects of material cold straining. This explains the behaviour differences between the idealized behaviour of the joint and actual behaviour.

Depending on the type of analysis, can be choose different modes of idealization of the characteristic M – �: elastic modelling for elastic analysis, rigid-plastic modelling for a rigid-plastic analysis (Fig. 8) and a nonlinear modelling for the elastic-plastic analysis (Fig. 9).

(a) (b)

Fig.8 Moment-Swivel Rigid-Plastic representation [7]: a.Elastic checking; b.Plastic checking

(a) (b)

(c)

Fig. 9 Moment-Swivel characteristic nonlinear representation [7]: a.Bilinear representation; b.Trilinear representation; c. Nonlinear representation

The approximate M-� curve can be obtain through experimental testing or mathematical models

based on the geometrical and mechanical properties of the joint. On scale experimental testing are the most reliable methods of description of the rotational behavior of the joints. These experiments are time consuming and expensive, thus cannot be regarded as a design procedure. Although during time a lot of


___ Idealized representation


___ Idealized representation

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experiments have been done and there were developed mathematical models for representation of the M- � curve. These mathematical models include: (i) curve fitting to test results by regression analysis, (ii) simplified analytical models, (iii) mechanical models that take into account the various sources of joint deformability and (iv) numerical models.

Current design practice adopts the Eurocode component method for the prediction of the rotational behavior of beam-to-column joints. Thus the joint can be subdivided into three different zones: tension, compression and shear. In each area, several sources of deformability can be identified, which are simple elemental parts (or “components”) that contribute to the overall response of the joint: (1) column web in shear, (2) column web in compression (3) column web in tension (4) column end plate in bending, (5) beam end plate in bending ( 6) beam web tensioned or compressed; (7) tensioned bolts (8) tensioned welding.

In principle, this methodology can be applied to any joint configuration and loading conditions provided that the basic components are properly characterized. Essentially, the method involves three basic steps: (i) identification of the active components for a given structural joint, (ii) characterization of the individual component F-� response and (iii) assembly of those elements into a mechanical model made up of extensional springs and rigid links. This spring assembly is treated as a structure, where F-� behavior is used to generate the M-� curve of the full joint.

Fig. 9. Active components and mechanical model adopted by Eurocode 3

for characterization of the joint rotational stiffness – welded beam-column joint

Fig. 10. Active components and mechanical model adopted by Eurocode 3

for characterization of the joint rotational stiffness – bolted beam-column joint The basic joint components are modeled through means of nonlinear extensional springs (Fig.

11a; K: spring axial stiffness). The complex behavior of the joint can be approximated with simple relationships without significant loss of accuracy. The elastic-perfectly plastic response is one of the possible idealizations. Following the Eurocode 3 approach for idealization of the flexural joint spring nonlinear behavior, this response is characterized by a secant stiffness, ke/�, and a full plastic resistance, FRd (Fig. 11b). ke is the initial stiffness of the component and � is a stiffness modification coefficient. Eurocode 3 defines this coefficient for different types of connections. For a single component, similar values can be adopted. The post-limit stiffness, kp-l is taken as zero, which means that strain hardening and geometric nonlinear effects are neglected. Regarding the

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component ductility, i.e. the extension of the plastic plateau, the code [5] presents some qualitative principles that are however insufficient. For instance, the component column web in shear has very high ductility and therefore the deformation capacity is taken as infinite; on the other hand, the bolts in tension are brittle components with no plastic plateau.

(a)

(b)

Fig. 11. Modelling of a component subjected to compression: a. Extensional spring representing a generic component; b. Actual behavior and elastic-plastic response

CONCLUSIONS

In the current design is necessary to adopt the use of a wide range of types of joints. The use of semi-rigid joints type, requires an assessment of ductility (rotation) in node and therefore an assessment of the entire nonlinear moment-swivel response of the joint.

The component method accepted by the standards for wide use in current practice does not provide the information necessary for more complex joints; more than that, it provides separate procedures to evaluate the initial strength and stiffness of steel and composite joints. These procedures set out in Eurocode 3 and Eurocode 4 regulations, are reproducing these properties in a satisfactory manner with the possibility of ease calculation.

Ductility evaluation presents two difficulties when compared with the initial strength and stiffness: knowledge of the nonlinear force - deformation response of each component and knowledge of the nonlinear moment-rotation response of the joint. The first problem is still insufficiently explored in the literature, most research is focused on assessing the strength and rigidity of structural components. The second problem requires numerical iterative procedure, because of plasticization and instability phenomena.

Assuming known the nonlinear behavior of components, it is necessary to determine the total nonlinear moment-rotation response of the joint type and consequently determination of resistance, initial stiffness and maximum rotation of the joint. REFERENCES 1. DUBINA, D., STRATAN, A. (2002), Behaviour of welded connections of moment resisting frames

beam to column joints, Engineering Structures, Vol. 24, No. 11, pp. 1431-1440. 2. BALLIO, G. (1985), ECCS Aproach for the Design of Steel Structures against Earthquakes, Symposium

on Steel in Buildings, Luxembourg, 1985, IABSE-AICP-IVBH Report, Vol.48, pp. 373-380. 3. BART, A.S., BOWMAN, M.D. (2001), Effect of local details on ductility of welded moment

connections, Journal of Structural Engineering, ASCE, 127(10):1145-1151.

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4. *** EUROCODE 3 Part 1.1 Design of steel structures, General rules and rules for buildings. CEN, European Committee for Standardization.

5. *** EUROCODE 3 Part 1.8 Design of joints of steel structures. CEN, European Committee for Standardization.

6. *** EUROCODE 8 - Design provisions for earthquake resistance of structures - Part 1-1: General rules - Seismic actions and general requirements for structures, CEN, ENV 1998-1-1.

7. SIMO˜ES DA SILVA, A. GIRA˜O COELHO (2001), A ductility model for steel connections, Journal of Constructional Steel Research 57, pp. 45–70.

8. SIMO˜ES DA SILVA, ANA GIRAO COELHO (2002), Evaluation of ductility in steel and composite beam-tocolumn joints: analytical evaluation, Journal of Constructional Steel Research.

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GNSS AUGMENTATION SERVICES IN ROMANIA

RUS Tiberiu, Technical University of Civil Engineering Bucharest, e-mail: [email protected]

A B S T R A C T The paper presents theoretical and practical aspects of the GNSS augmentation systems and services. As today the people know what is GPS and how can be used in navigation, in general aspects of the GNSS augmentation systems are unknown or poor. Definition and implementation of GNSS augmentation systems are presented at global, regional and national level. With the help of GNSS augmentation systems, the position determination it is improved from metre level (for GNSS standalone systems) to decimetre, centimetre up to millimetre level (GNSS standalone plus augmentation system). The benefits of such systems and services are emphasized. As realizations there are mentioned the most known as EGNOS (in Europe), ROMPOS, Trimble VRS Now and Leica TGRef (in Romania), OMNISTAR and STARFire (at global level). Depending on the area and application, the users can choose between these augmentation systems or others available. The paper presents considerations especially for the centimetre level position accuracy determination based on DGNSS/RTK services.

Keywords: DGNSS, RTK, absolute/relative positioning


INTRODUCTION Today in the Geodesy applications there are often applied GNSS technologies and methods

for positioning. Coordinates are determined in specific reference systems with m, dm, cm and mm accuracies. Depending on the application, different methods are available. For navigation m and dm accuracies are good enough, but for other applications as geodetic networks or cadastre positioning cm and mm accuracies should be achieved. At the international and national level there are now available GNSS specific services based on GNSS permanent stations networks. These services acts as augmentation systems providing additional information for GNSS users in order to improve positioning accuracy in comparison with standalone (absolute) positioning. The paper presents considerations on the status of GNSS augmentation services available in Romania with focus on geodetic users and RTK (Real Time Kinematic) positioning. MATERIALS AND METHODS 1. Considerations on GNSS Augmentation Systems

GNSS (Global Navigation Satellite Systems) have a continous evolution since 1980s. Based on navigation satellites, other domains benefits today of that positioning technologies: geodesy, geodynamics, meteorology, civil engineering, topography and cadastre et al. Satellite positions are known and ranges measured from ground antennas to the broadcasting satellites are measured by methods as code correlation or carrier phase observations. Ground positions are determined as absolute (point positioning) or relative positions. In general absolute positioning (origin in the centre of mass of the Earth or geocentre) it is specific for navigation with meter or decimetre accuracies and relative positioning (origin choosed arbitrary) it is specific for more accurate applications with centimetre or millimetre accuracies (Fig.1) [1].

Positions determined by GNSS are expressed in different Coordinate Reference Systems (CRS) or datums as ITRS (International Terrestrial Reference System), ETRS89 (European Terrestrial Reference System 1989), WGS84 et al. For daily applications coordinates expressed in such reference systems can be transformed in local datums, as S42 (Krasovski ellipsoid 1940) in

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Romania. According to 2007 European Directive INSPIRE, for EU Member States, the ETRS89 CRS with latest realization should be used.

Fig.1. Principles of GNSS positioning (absolute vs. relative)

The most known GNSS systems available today are GPS or NAVSTAR-GPS (USA) and

GLONASS (Russia). New GNSS systems are going to be realized in Europe – named GALILEO and in China – named COMPASS/BeiDou. Similar systems will be realized in Japan and India. Each such a system includes three major components: space segment, control segment and user segment (Fig.2).

Fig.2. GNSS segments and augmentation systems

A satellite-based augmentation system (SBAS) is a system that supports wide-area or regional

augmentation through the use of additional satellite-broadcast messages. Such systems are commonly composed of multiple ground stations, located at accurately-surveyed points. The ground stations take measurements of one or more of the GNSS satellites, the satellite signals, or other environmental factors which may impact the signal received by the users. Using these measurements, information messages are created and sent to one or more satellites for broadcast to the end users [2].

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In adition to GNSS systems, there are realized augmentation systems providing additional information for GNSS users in order to improve positioning accuracy in comparison with standalone (absolute) positioning. Additional information includes mainly differential corrections calculated based on the GNSS permanent station networks. If corrections are calculated based on code observations at permanent stations they are named D-GNSS corrections and if are calculated based on phase observations, they are named RTK (Real Time Kinematic) corrections. Today there are available two concepts for corrections calculation: based on a single base station or based on a network of GNSS permanent stations [1].

An example of GNSS permanent network at global level it is the IGS (International GNSS Service) network (Fig.3a, Fig.3b). For Europe was realized such a network named EUREF-EPN (European Reference Frame – Permanent Network, Fig.4). Romania contributes at these networks with one station (named BUCU – Bucharest) for IGS and five stations for EUREF-EPN. At national level in Romania was realized by National Agency for Cadastre and Land Registration (ANCPI) a GNSS permanent station network including 60 stations (2011) up to 75 stations (2012) [3]. Private companies realized more sparse GNSS permanent networks in Romania. Trimble company operates 9 stations and Leica company operates 8 stations.

Fig.3a. IGS GNSS permanent station network (world view) [4]

Differential corrections are disseminated by various means such as radio transmitters, GSM,

internet, satellite communications. At global and regional level DGNSS corrections are broadcasted via satellites. For GPS as regional augmentation system in North America was realized WAAS – Wide Area Augmentation System including 2 geostationnary satellites. A similar augmentation system it is available in Europe by EGNOS (European Geostationary Navigation Overlay System) including 3 geostationnary satellites.

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Fig.3b. IGS GNSS permanent station network Fig.4. EUREF-EPN permanent station (Europe view) [5] network [6]

Based on GNSS permanent network stations there are available different kind of services. In

general GNSS services includes raw data services (in RINEX or Virtual-RINEX form) and DGNSS/RTK services. In addition, automatic data processing and meteo data services can be provided to the users.

2. GNSS Augmentation Systems available in Romania 2.1. ROMPOS Services

According to the global and European trends in the field of modern geodetic networks, Romania followed this trend by promotion and implementation of a new high accurate geodetic network in the time interval 2004-2010. The new geodetic network it is build as an active continuously operating network. As technological equipments the GNSS (GPS and GPS+GLONASS) receivers are included into the network.

Starting in 1991 with first GPS equipments and continued in 1999, when it was installed the first GPS permanent station in Romania (BUCU) at the Faculty of Geodesy - Technical University of Civil Engineering Bucharest in cooperation with Federal Agency for Cartography and Geodesy Frankfurt a.M. (Germany), the new methods of global satellite positioning were introduced in Romania. In present Romania realized a GNSS permanent network including 60 stations (75 stations at the end of 2012, Fig.5a) and provides GNSS augmentation services under ROMPOS – Romanian Position Determination System. ROMPOS it is a part of the Central and East Europe ground station augmentation system named EUPOS (Fig.5b). ROMPOS services includes DGNSS service (dm accuracy), RTK service (cm accuracy) and GEO (geodetic service – cm/mm accuracy). DGNSS/RTK services can deliver augmentation data (corrections) based on single base or network (FKP, VRS, and MAC) concepts. Data are transmitted continuously by internet and NTRIP protocol. These services are still free of charge. GEO (postprocessing) service provides raw GNSS (RINEX) data by internet and it is charged. An overview of ROMPOS services it is presented in Table 1.

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Fig.5a. ROMPOS GNSS permanent stations [3] Fig.5b. EUPOS GNSS permanent stations [7]

Table 1. ROMPOS Services Service Availability Transmision media Data format Rate

DGNSS Realtime Internet / NTRIP RTCM 2.x 1s RTK Realtime Internet / NTRIP RTCM 2.x

RTCM 3.x 1s

GEO

Postprocessing Internet / (FTP,HTTP) (V)RINEX 2.x GPS (G) GPS&GLONASS (M)

1s, 5s, 30s

2.2. TRIMBLE VRS NOW Services

Trimble company realized in USA and Europe, GNSS services based on GNSS permanent station networks. Trimble services are known under the name „Trimble VRS Now” due to the VRS (Virtual Reference Station) concept implemented for the first time by this company. Trimble VRS Now includes realtime services DGNSS and RTK. Starting with 2012, Trimble VRS Now services are available in Romania. These services are provided in Romania based on a GNSS permanent network including 9 GNSS permanent stations installed in the area (Fig.6). There are a various number of GNSS receivers able to work with Trimble VRS Now services, able to process CMR and CMR+ data formats. Such equipments are provided mainly by GISCAD SRL company in Arad. Access to these services can be realized by SYSCAD SRL company in Bucharest. There are available few types of registration (monthly, yearly). There are first private DGNSS/RTK services provided in Romania by a private company with full country coverage.

With the support of GISCAD SRL company, we performed GNSS RTK tests using Trimble VRS Now services. Few tests were performed in order to compare absolute known coordinates (in ETRS89 reference system) with coordinates determined for the same points with these services. In the same time we compare coordinates obtained by use of Trimble VRS Now services and ROMPOS similar services. Connection to the data server and initialization time was investigated for the new services. The results indicate a good (short) initialization time and a good agreement with ROMPOS solution. Further investigations are necessary to analyse services working in difficult conditions: long distances from the GNSS permanent stations, ionospheric high activity, worse internet data communication, VRS method compared with other concepts (FKP, MAC) etc.

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Fig.6. Trimble VRS Now GNSS permanent stations in Romania [8]

2.3. Leica TGREF Services

Leica Geosystems company realized in last few years DGNSS/RTK services based on GNSS permanent networks under the name of „Leica SmartNet” in Europe and other areas [http://www.smartnet-eu.com/]. In Romania, Leica Geosytems represented by TopGeocart SRL company established a GNSS permanent station network named TGRef including 8 stations (Fig.7) and DGPS, RTK (single base) and postprocessing services. RTK service transmits corrections in Leica proprietary format.

Fig.6. Leica TGRef permanent stations in Romania [9] 2.4. EGNOS Services

Known as a satellite-based augmentation system (SBAS), EGNOS (European Geostationary Navigation Overlay System) provides both correction and integrity information about the GPS system, delivering DGPS corrections for Europeans and improving existing services or developing a wide range of new services and applications. In the future EGNOS will be able to augment GNSS - GALILEO in Europe. The EGNOS signal is broadcast by 3 satellites: two Inmarsat (one positioned east of the Atlantic, and the other above Africa) and by ESA’s Artemis satellite, which is also above Africa. The orbits of these satellites are in the equatorial plane, at three different

PRIVATE GPS PERMANENT

STATIONS NETWORK

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longitudes, with each able to broadcast EGNOS services across Europe. “Unlike GPS, EGNOS will offer integrity of signal, increased accuracy, coverage and a service level agreement. This makes it suitable to provide a number of navigation services. For the most common applications, EGNOS gives a positioning accuracy of one to three metres, compared to the less accurate 10 to 15 m provided by GPS alone. The three services available are: Open Service, Safety-of-Life Service, EGNOS Data Access Server (EDAS)” [10].

The EGNOS Open Service has been available since 1st of October 2009. EGNOS DGPS corrections are freely available in Europe through geostationary satellite signals. Every user equipped with an EGNOS capable GPS receiver can determine a position without any direct payment. “Since 1st of March 2011, EGNOS Safety-of-Life (SoL) signal was formally declared available to aviation. For the first time, space-based navigation signals have become officially usable for the critical task of vertically guiding aircraft during landing approaches” [11]. EGNOS provides also a terrestrial commercial data service called the EGNOS Data Access Service (EDAS). EDAS provides postprocessing and realtime data collected and generated by the EGNOS infrastructure.

In Romania EGNOS system it is at present less used and needs a better promotion in order to inform the potential beneficiaries of services. According to geographic position of Romania, at the eastern border of EGNOS services, a better coverage would be necessary in the future if uniform services should be provided for all EU countries. As an example, GNSS permanent station in Bucharest (BUCU) it is able at present to track EGNOS signal in addition to GPS and GLONASS signals. 2.5. OMNISTAR Services

OmniSTAR is a leader in providing high accuracy positioning data via satellite, including Differential GNSS (DGNSS) positioning technology. Using over 100 reference stations, 6 high power satellites and 2 global network control centers, OmniSTAR delivers real-time and highly reliable positioning services for land and air applications worldwide (Fig.8) , 24hrs a day 365 days a year. Available services are:

� OmniSTAR HP: 2- 4" (6-10 cm) � OmniSTAR XP: 4 - 6" (10-15 cm) � OmniSTAR G2: 4 - 6" (10-15 cm) � OmniSTAR VBS: < 1 meter

Fig.8. OmniSTAR coverage area [12]

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2.6. StarFire Services StarFire is a wide-area differential GPS developed by John Deere's NavCom and precision

farming groups. StarFire broadcasts DGPS correction information over satellite L-band frequencies around the world, allowing a StarFire-equipped receiver to produce position measurements accurate to well under one meter, with typical accuracy over a 24-hour period being under 4.5 cm. “StarFire has developed through two versions. The first, retroactively known as SF1, offered 1-sigma accuracy of about 1 m. This system was first offered in 1998. The newer system, SF2, was introduced in 2004. It dramatically improves accuracy, with a 1-sigma absolute accuracy of about 4.5 cm. The relative accuracy is likewise improved, to about 2.5 cm.” [13]. In Europe, StarFire services are offered by Trimble and Fugro companies. CONCLUSIONS

Today GNSS systems and their augmentation systems are very important tools for various applications. DGNSS/RTK systems and services are more and more spreaded all around the world. In Romania GNSS augmentation systems are developed by state or private companies. According to European standards, in Romania was realized ROMPOS augmentation system with DGNSS/RTK free of charge services and postprocessing charged services. In addition, private companies realized or ar going to realize similar services based on private GNSS infrastructure, as Trimble VRS Now or Leica TGRef networks and services. Other GNSS augmentation systems are available but rarely applied, as EGNOS, OmniSTAR or StarFire. A better future can be available in Romania for private GNSS augmentation systems as Trimble VRS Now and Leica SmartNet if we consider the large area of GNSS applications. REFERENCES 1. RUS T. (2012), Space Geodesy I, Lecture Notes, Technical University of Civil Engineering, Bucharest,

Romania. 2. *** http://en.wikipedia.org/wiki/GNSS_augmentation viewed at 12 September 2012. 3. RUS T., MOLDOVEANU C., DANCIU V., Considerations on the State of Romanian National Geodetic

Network, International Symposium GeoCAD 2012, May 2012, Alba Iulia, Romania. 4. *** http://igscb.jpl.nasa.gov viewed at 12 Sep 2012. 5. *** http://igscb.jpl.nasa.gov viewed at 12 Sep 2012. 6. *** http://epncb.oma.be viewed at 21 Mar 2012. 7. *** www.eupos.hu/EUPOS-ESDB.php viewed at 10 Aug 2012. 8. *** http://www.cadsolutions.ro/trimble-vrs-now-serviciul-de-corectii-rtk.php viewed at 12 Sep 2012. 9. *** http://www.topgeocart.ro/statii_referinta viewed at 12 Sep 2012. 10. *** http://egnos-portal.gsa.europa.eu/discover-egnos/about-egnos; viewed at 12 Sep 2012. 11. *** http://www.egnos-pro.esa.int/ viewed at 12 Sep 2012. 12. *** http://www.omnistar.com/ viewed at 12 Sep 2012. 13. *** www.en.wikipedia.org viewed at 12 Sep 2012.

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RC FRAMED BUILDING REHABILITATED IN DIFFERENT WAYS, SUBJECTED TO SEISMIC LOADS

SANDOR Florin*,CHIRA Alexandru,

Technical University ofCluj-Napoca, *e-mail: [email protected] (corresponding adress)

A B S T R A C T This paper presents a study on the seismic behaviour of a structure rehabilitated in different ways and subjected to seismic loads. The structure that is used in this study was previously analysed at seismic loads and it has been determined that it’s seismic capacity was exceeded and damage that lead to collapse appeared. Several rehabilitation methods were used like: recasting a new layer of reinforced concrete, applying FRP layers and using steel layers for the beams and columns of the structure. All the rehabilitation methods were numerically tested at seismic loads using a dynamic nonlinear analysis with the help of the finite element code software Abaqus.

Keywords: recast, FRP layers, nonlinearity , rc framed building, collapse, damage, Abaqus


INTRODUCTION After observing the precarious seismic behaviour of a reinforced concrete framed building[1],

designed usingP13-70 [2], the problem of taking measures for the integrity of this type of structures was taken into account. Several methods were proposed for numerical investigation using the romanian code P100-3/2006 [3]. The methods that were used are: recasting a new layer of reinforced concrete,applying FRP [4] layers and using steel layers for the beams and columns of the structure. For the FRP layers two cases were studied: the first one using a layer only for the beams and the second one for both beams and columns. MATERIALS AND METHODS 1. Rehabilitation methods. Analysis, loads and materials

Recasting a new layer of reinforced concrete In respect with the prescriptions of P100-3/2006, the recast layer for the beams and columns

was for all their length excepting the beam and column ends where we have a free portion of 30

mm. The concrete used for the recast was C20/25 with 4 longitudinal reinforcements �14 ( 2 up

and 2 down) and �10/200 transversal reinforcement. Applying a steel layer over the beams and columns For all the beams and columns was applied a layer of steel ( 2 U S235 profiles that were

merged using steel plates with welding) having a thickness t=5 mm. As in the previous case the steel was applied for all the beams and columns length excepting the ends were we have a free portion of 30 mm.

FRP layer over the beams A FRP layer was applied over all the beams length. The FRP consists actually of 2 layers

having different orientations (0° and 90°). FRP layer over the beams and columns A FRP layer was applied over all the beams and columns length. As in the previous case the

FRP consists of 2 layers having different orientations (0° and 90°).

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Fig.1. Recast with concrete

Fig.2. Steel layer Fig.3. FRP layer over the beams

Fig.4. FRP layer over the beams and columns

Materials Concrete material properties (C20/25): Young’s modulus E=3E07 kN/m2; Poisson’s coefficient �=0.2;

Table 1. Concrete damaged plasticity parameters

ψψψψ M γγγγ ρρρρ ηηηη 32 0.519 1.17 0.7 0.01

Table 2. Compression

Yield

[Kn/cm2] Inelastic strain

2.254 0

2.692021 0.000626

2.8 0.00107

2.648767 0.00192

Table 3. Tension Yield

[kN/cm2] Cracking strain

0.318 0

0.217 0.000412

Steel (PC 52 and S235): Young’s modulus E = 2.1E08 kN/m2; Poisson’s coefficient � = 0.3;

Table 4. Steel plasticity PC52 Table 5. Steel plasticity S235

Yield [kN/cm2] Plastic strain 34.5 0

Yield [kN/cm2] Plastic strain 23.5 0

A dynamic nonlinear explicit analysis was used for all the methods proposed above using Vrancea accelerogram with an integration step of 0.01 s. For solid elements involving beams and columns and also steel layer a C3D8R mesh type was used and for reinforcement T3D2 truss mesh type with perfect bond between the two materials [5,6].

For the FRP layer a shell section was used and a nonlinear lamina material law using strain and stress fail [7,8].

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FRP properties: -E1=172400 kN/cm2; -E2=6900 kN/cm2; -E2=6900 kN/cm2; -�12=0.25 ; -G12=G13=3450 kN/cm2; -G23=1380 kN/cm2;

Fail stress: -tension stress fiber direction:0.0207kN/cm2; -compression stress fiber direction: -0.00828kN/cm2; -tension stress transversal fiber firection:0.000345kN/cm2; -compression stress transversal fiber direction:-0.00103 kN/cm2; - shear strength: 0.000689kN/cm2;

Strain fail: -tension strain fiber direction: 0.17; -compression strain fiber direction: -0.07; -tension strain transversal fiber firection: 0.05; -compression strain transversal fiber direction: -0.013; -shear strain: 0.11;

2. Results

The results from the dynamic analysis for the proposed rehabilitation methods are: Steel layer over the beams and columns

Fig.5. Plastic strain from tension in concrete, �pl=1.44E-4, T=7.23 s


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Fig.7. Plastic strain in reinforcement, �pl=0, T=15.99 s

Fig.8. Plastic strain in steel layer, �pl=0, T=15.99 s

Fig.9. Top displacement Fig.10. Shear base force

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Recasting a new layer of reinforced concrete

Fig.11. Plastic strain from tension in

concrete, �pl=1.1, T=19.47 s Fig.12. Plastic strain from tension in concrete

recast, �pl=4.13 , T=19.47 s

�Fig.13. Plastic strain in reinforcement,�pl=2.66E-1 , T=19.47 s

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FRP layer over the beams


Fig.17. Plastic strain from compression in concrete , �pl=2.59E-5 , T=40.14 s

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FRP layer over the beams and columns

Fig.20. Plastic strain from tension in

concrete, �pl=0, T=40.14 s Fig.21. Von mises stress in concrete, �=2.55E-2 kN/cm2, T=40.14 s

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Fig.22. Top displacement Fig.23. Shear base force CONCLUSIONS

From all of the rehabilitation methods proposed only the one with frp layers on both columns and beams presented a good overall behaviour with no damage occurance. The worst behaviour was obtained from the structure with concrete recast,the analysis was terminated at 19.47 s because of the structure collapse. In general the main problem was that the joint was not treated in the rehabilitation process. The most efficient but expensive as cost remains the FRP layers method, applied on beams and columns.

ACKNOWLEDGEMENTS

This paper is a continuation of the material presented initially under the name Rc framed building designed with P13-70 seismic code, subjected to seismic loads. REFERENCES 1. *** P13-63, Normativ condi�ionat pentru proiectarea construc�iilor civile �i industriale din regiuni

seismice (Conditioned Seismic design code for civil and industrial buildings). 2. *** P100-3/2006, Cod de evaluare �i proiectare a lucr�rilor de consolidare la cl�diri existente,

vulnerabile seismic (Evaluation and design code for consolidation of existing buildings, seismic vulnerable).

3. *** Abaqus Cae,User’s Manual. 4. LEE, J., and FENVES G. L. (1998), Plastic-Damage Model for Cyclic Loading of Concrete Structures,

Journal of Engineering Mechanics, vol. 124, no.8, pp. 892–900. 5. GIL BEATRIZ & BAYO EDUARD (2008), An alternative design for internal and external semi-rigid

composite joints. Part II: Finite element modeling and analytical study, Engineering Structures; 30; pp. 232-246.

6. PAGANO, N. J. (1969), Exact Solutions for Composite Laminates in Cylindrical Bending, in Journal of Composite Materials, vol. 3, pp. 398–411.

7. STOIAN V., NAGY-GYORGY T., DAN D., GERGELY J., DAESCU C. (2009), Materiale compozite pentru construc�ii, Editura Politehnica Timi�oara, ISBN 978-973-625-948-7.

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MODERN METHOD TO WATERPROOFING REHABILITATION FOR BUILDING INFRASTRUCTURE

T�MA� Florin-L.*, TUNS Ioan,

Transilvania University of Bra�ov, e-mails: * [email protected] (corresponding adress), [email protected]

A B S T R A C T The issue of waterproofing isolation for buildings is always present. Even with the technology which has progressed greatly, both in terms of materials and systems used, putting these into practice is a factor insufficient controlled from the qualitative point of view. At the existing buildings and especially the old ones, the defects have been caused by rising humidity, condensation, salt attack, degradation of structural materials. The aim of this paper is to present a modern method used to waterproofing rehabilitation for building infrastructure. Therefore we describe some technological characteristics, such as different types of ecological solutions used and their quantities necessary to inject the walls, as long with few of the objectives where successfully applied.

Keywords: brick walls, moisture, ecological solution, insulation


INTRODUCTION The decay of masonry, plaster and even paintwork or decoration is caused by the rise of water

in construction materials through the capillary effect: a phenomenon which affects civil construction in general and a large part of our building heritage.

This phenomenon is known for a long time, but was seen as a foreseeable and inherent aspect of the construction, during its life. Rising humidity is caused by the presence of water in the soil and by the capillary action of construction material; it can be seen above all through the appearance of stains at the bottom of walls, with cracking paintwork and flaking plaster or fragments of construction materials (stone, brick, etc.). As a result of low surface tension, capillary channels allow water to rise, the presence of salts in the soil or building materials promoting further expansion process.

Besides the aesthetic damage, rising humidity increases the dispersal of heat from the inside of the building to the outside and also causes the internal relative humidity to rise, leading to sanitary and environmental problems [1].

MATERIALS AND METHODS 1. DryKit technology

One of the methods to combat moisture from buildings is sealing masonry with different waterproofing solutions, which may be introduced into the porous by injection (by pressure) or by electric means of transportation (electrochemical method) [2]. The method described bellow (based on the injection procedure) is called DryKit and is an exclusive patented system for fighting rising humidity, which eliminates the problem for good. This system acts on masonry through the formation of a chemical barrier consisting of water or solvent-based hydrophobic formula.

2. Hydrophobic formulas used

According to this method, the continuous chemical barrier which is guaranteed and unalterable in time can be obtained by use of different formulas (solutions), few of them are described bellow.

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- TRE 128 environmental friendly - specifically formulated siloxane microemulsion-based solvents in heteropolar hydrolysates for walls of any type of material or thickness to be applied by insertion of diffuser tube shaped made from pressed cellulose at a series of holes passing near, prepared at 15 cm from the floor.

- TRS 114 - formulated specifically based on polysiloxanes in aliphatic solvent, for walls of any material or thickness to be applied by insertion of diffuser tube shaped made from pressed cellulose at a series of holes passing near, prepared at 15 cm from the floor.

- TRX 118 - monomeric silane component formulation with high penetration of any masonry material or thickness to be applied as mentioned above.

- TRA 115 - silicone formulated in deionized water suitable for masonry or stone, for compact brick masonry with a thickness greater than 40-50 cm, to be applied as mentioned above.

- TRF 135 - formulated specifically based on modified polysiloxane solvents super rectified, for the treatment of frescoed walls, to be applied by insertion of speakers tubopress of cells at a series of holes almost loops, drawn 15 cm from the floor share.

The drying time of a treated wall may vary depending on the actual construction of the wall, weather conditions, the wall thickness, type of product formula used, water or solvent (table 1) [3].

Table 1. Drying time of treated walls

Wall average drying time, when TRX 118 and TRA 115 was used

Wall average drying time, when TRS 114, TRF 135 and TRE 128 was used

Wall thickness, [cm] Time, [days] Wall thickness, [cm] Time, [days] 05 35 05 20 10 50 10 25 15 75 15 40 20 95 20 50 25 120 25 60 30 145 30 75 35 170 35 80 40 195 40 100 45 215 45 115 50 240 50 125 55 265 55 140 60 290 60 150 65 310 65 180 70 335 70 200 75 360 75 225 80 385 80 240 85 400 85 255 90 430 90 270

Graphical representation for the variation of drying time, depending on the wall thickness of

the treated wall, for the two categories of solutions – A, respectively B – are according to figure 1 [4].

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�Fig.1. Graphical variation for A, respectively B solution type

3. Technological specifications

DryKit technology is used for stone masonry or mixed (brick, stone). The principle of this method is to create a chemical barrier in order to stop the capillary phenomenon. Basically, fholes are practiced into the wall, through which special solutions are injected. The injection process prevents leakage through cracks in masonry. The procedure for DryKit technology is as follow (fig. 2, fig. 3, fig. 4 and fig. 5).

� Fig.2. Drilling holes into the wall Fig.3. Introduction of cellulose tubes into the holes �

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�Fig.4. Fixing pouches filled with hydrophobic Fig.5. Technological ensemble solution at the cellulose tubes CASE STUDIES

Some of the main objectives observed during time and to which DryKit system was applied for draining brick (or stone) walls affected by capillary moisture will be presented below.

1. „Ilie Birt” memorial house, Bra�ov

According to technical expertise [5] and in order to create a rising dump barrier DryKit method was applied. Some measures and images from work site are presentedas follows:

- Execution of horizontal holes at 15 cm interspaced throughout the wall thickness but less than 5 cm, where tube shaped diffuser made from pressed cellulose will be inserted; method applied at interiour walls (fig. 6):

Fig.6. DryKit method applied at interior walls

- TRE 128 ecological solution will be dose (product specifically designed for this kind of

work that does not degrade the paintings and materials which came in contact with) depending on the thickness of the walls and ensure connection to diffusers, for scattering in the walls. Dispersion may take between 1 hour and 24 hours depending on the walls materials porosity and their capillary.

- In this way, a chemical barrier around (25-30) cm thickness will be achieved throughout the wall section.

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Fig.7. DryKit method applied at exteriour walls

2. „Buna Vestire” church from Jina village, Sibiu county

For this objective, measurements have revealed high levels of moisture in the walls of the church, which exceeded 35% both in the exterior (fig. 8) and interior walls. In time, this problem has caused degradation of paintings, the emergence and persistence of mold odor and health hazard to the inhalation of harmful fungi. The humidity high in the walls was about 1.80 m [7].

Fig.8. Capillary moisture present at exteriour walls

The technical specification was followed exactly and the results can be observed bellow

(fig. 9).

Fig.9. Positive effect to the walls,

after applying DryKit method

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CONCLUSIONS The use of DryKit system in order to eliminate the capillary moisture from brick walls has a

number of advantages, such as: - Transfusion time of hydrophobic solution is very small; - Masonry manages to completely absorb the required amount of solution in less than 24

hours; - Convenience and ease of implementation; - Guaranteed results over time.

REFERENCES 1. T�MA�, F.-L., TUNS, I., STREZA, T. (2010), Considerations related to waterproofing brick walls

affected by capillary moisture and case study, International Scientific Conference CIBv 2010, 12-13 November, Bra�ov.

2. T�MA�, F.-L., TUNS, I. (2010), Removing capillary moisture from brick walls using a drying method and case study, Bulletin of the Transilvania University of Brasov, vol. 3 (52)-2010, Series I – Engineering Sciences.

3. *** www.drykit.it, viewed at 13/02/2012. 4. T�MA�, F.-L. (2012), Contribu�ii privind reabilitarea hidroizola�iilor la infrastructura cl�dirilor civile,

(Contributions to waterproofing rehabilitation for building infrastructure), Ph.D. Thesis, 23 march 2012, Technical University of Cluj-Napoca, Faculty of Civil Engineering.

5. T�MA�, F.-L., STREZA, T. (2006), Expertiz� tehnic� privind lucr�ri de eliminare a umidit��ii capilare din zidurile subsolului cl�dirii Casa memorial� „Ilie Bir�”, (Technical expertise for removing capillary moisture from the basement walls of “Ilie Birt” memorial house), Bra�ov.

6. *** www.recon.ro, viewed at 15/03/2012. 7. STREZA, T. (2007), Expertiz� tehnic� privind lucr�ri de eliminarea umidit��ii capilare din zidurile

Bisericii Ortodoxe, com. Jina, jud. Sibiu, (Technical expertise for removing capillary moisture from walls of Ortodox Church in Jina, Sibiu county).

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NUMERICAL MODELING OF REINFORCED CONCRETE WALL PANELS WEAKENED BY CUT-OUTS

TODU� Carla*, STOIAN Valeriu, NAGY-GYÖRGY Tamás, DEMETER István,

Politehnica University of Timi�oara, *e-mail: [email protected] (corresponding adress)

A B S T R A C T Precast reinforced concrete large panel structures were built in Romania between 1960-1990. New cut-out requirements or enlarged openings in the structural walls may happen during the life of a building due to the change in functional destination of the buildings or other reasons. However these changes cause stress redistribution in the proximity of the cut-out intervention and sometimes it can affect the structure’s global behaviour. In this paper, a numerical analysis is presented in order to predict the response of the experimental tested shear walls with cut-out openings. A number of three specimens were considered in order to assess the lateral load capacity loss and compare the results caused by the cut-out. These walls are: a) a solid wall (S), b) a wall with narrow door cut-out (S/E1) and c) a wall with large door cut-out (S/E3). The paper provides a comparison of the analysed models with the experimental specimens tested in the Laboratory of Reinforced Concrete Structures, Politehnica University of Timi�oara.

Keywords: experimental walls, modeling, reinforced concrete wall, shear, precast, cut-out


INTRODUCTION Since there is a large number of precast reinforced concrete large panel buildings that were

built across the country, this attracts the interest in this type of structural system. During time this type of system proved good seismic behavior. Despite the excellent seismic performance its use was obstructed by certain factors such as the functional space requirement, valid from residential to commercial cases and which implied several types of cut-outs in the walls. Because of the fact that many of these buildings have already 50 years of existence, interventions on them become more and more necessary.

The objectives of the present paper are to evaluate the seismic performance of the specified wall panels numerically and compare it with the experimental results and also to investigate the weakening effect caused by the cut-out numerically versus experimentally. MATERIALS AND METHODS

For the current investigation the project type 770-81 “Cladiri de locuit P+4 din panouri mari” (“Precast reinforced concrete large panel buildings P+4”) [1] was chosen. The structural system is composed of a cast-in-place RC infrastructure (strip foundations and 200 mm thick RC walls) and the entirely precast superstructure.

The precast large panels were of three types: exterior wall, interior wall and slab. The exterior wall panels have a load-bearing layer (120 mm) and a thermal insulation layer (150 mm). Slab panels have the thickness of 130 mm while the interior walls thickness is of 140 mm.

The prototype panel for the experimental program was the interior longitudinal panel labeled I36-1 from the typical plan 770-81. The dimensions of this wall are 3300 mm length, 2580 mm height and 140 mm thickness, and it weighs 2900 kg. Experimentally the walls were scaled 1:1.2 model to prototype scale due to the capacity of the testing facility available in the laboratory.

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1. Experimental program description A part of an experimental program consisting of a solid wall (S), a wall with narrow door cut-

out (S/E1) and a wall with large door cut-out are presented in this paper [2]. These walls were already tested by I. Demeter in the Laboratory of Reinforced Concrete Structures, Politehnica University of Timi�oara. All these walls have in common the solid wall panel characteristics. The wall reinforcement consists of PC52 type (S355 grade) for 10 mm longitudinal bars and for 14 mm vertical continuity bars and STPB type (S490) for 4 mm welded wire mesh. The ultimate cubic compressive strength of concrete for the tested and modeled wall panel is 17.5 MPa.

275030

02 Ø 14

2 Ø 14H oopsØ 8/85

Ø 16

100100100100

Ø 14Ø 10/265 Ø 4/100

2150

1 1

1-1

W IN G

W E B

H oriz. barsØ 10/265

W elded w irem esh Ø 4/100

V ert. barsØ 14

Fig.1. Concrete outlines and reinforcement of the solid wall panel [1]

Figure 1 represents the concrete outlines and reinforcement of the solid wall panel. The panel

was provided with two wing elements in order to prevent the out of plane stability of the wall. The wing element is composed of a short in-plane connection zone and a flange perpendicular to the wall plane. Only the flanges of the wing are reinforced using spatial cages made of 4�14 mm longitudinal bars and �8 mm plain transverse hoops at 85 mm centers and a �16 mm vertical continuity bar. The web-to-wing connection was realized through anchoring the horizontal �10 mm panel-bars into the confined core of the flange.

2. The numerical analysis

In order to make sure that the results taken from the numerical analysis will be close enough to predict the real behavior of the wall panels, understanding and determining the geometrical and material characteristics as well as the mechanisms and conditions of the tested wall need to be clearly taken into account. Certain simplifications and differences were still made and these are later explained. The analysis was performed in a 2D model using the ATENA Software [3]. The tested specimen was laterally loaded, reversed cyclic- displacement controlled [2],[4]. In the modeled wall a lateral load was applied, displacement controlled of constant increments of 0.1 mm.

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In order to restrain the rocking rotation of the experimental walls, axial loads were imposed composed of a constant and a variable part [2],[5]. The axial loads for the modeled wall were considered taking into account the total loading applied experimentally and the number of steps performed by the analysis. The boundary conditions consist of restrained rotation in case of the tested wall while for the modeled wall the bottom side of the lower beam was fixed in both horizontal and vertical directions.

3. Solid wall results

The primary results of the tested and modelled wall are depicted in Table 1. Experimentally, the first inclined cracks developed at � = 2.87 mm drift level, extending from the top to the bottom edges. Figure 2 represents the experimental solid wall at testing. Due to the testing facility available in the laboratory the solid wall could not be loaded beyond 1210 kN. The drift level corresponding to the maximum lateral load imposed was of 8.6 mm drift level [2]. Numerically, the first inclined crack appeared at 0.7 mm drift level (Figure 4.b). The significant difference in crack appearance value can be associated to the fact that the numerical analysis records thin cracks not easily seen experimentally. The maximum lateral load imposed numerically was of 1380 kN and the failure of the element is a brittle one, as seen in Figure 3 on the load-displacement diagram. Figure 4.a shows the outlines of the element in the numerical analysis and Figure 4.c represents the compressive stress in the point on the load-displacement diagram where it decreases suddenly.

Table 1. Solid wall comparison results [6], [7]

SOLID WALL RESULTS

Element First inclined cracks Maximum lateral load imposed

Drift level corresponding to max lateral load imposed

Tested � = 2.87 mm drift level 1210 kN 8.6 mm

Modeled � = 0.70 mm drift level 1380 kN 7.43 mm

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Fig.4. Numerical a)solid wall outlines, b) 1st diagonal crack , c) compressive stress at 7.43 mm 4. Wall with narrow door cut-out results

Table 2 comprises the comparison results for the S/E1 wall. For the modeled wall the first diagonal crack appeared much earlier than in the case of the tested wall. The thickness of the first diagonal crack in the case of the modeled wall is small enough in order to not be easily seen experimentally. Figure 5 represents the experimental wall with narrow door cut-out at testing. The load-displacement diagram is presented in Figure 6. The modelled wall presents an initial higher stiffness and a more ductile behaviour than the modeled solid wall. Figure 7.a shows the numerical outlines of the specimen, Figure 7.b the state of the element at the occurrence of the first inclined crack and Figure 7.c represents the compressive stress of the wall where the ultimate compressive strength of concrete was attained.

Table 2. Wall with narrow door cut-out comparison results [6]

WALL WITH NARROW DOOR CUT-OUT RESULTS

Element First diagonal crack Maximum lateral load imposed


Tested � = 6.28 ÷ 7.85 mm drift level 581.8 kN 9.42 mm

Modeled � = 1.23 mm drift level 541.8 kN 4.7 mm

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Fig.7. Numerical a) S/E1wall outlines, b) 1st diagonal crack , c) compressive stress at 5.54 mm

5. Wall with large door cut-out results

Table 3 comprises the comparison results for the S/E3 wall. Here we have also a significant difference in the value of the crack appearance. Figure 8 represents the experimental wall with large door cut-out at testing. The load-displacement diagram is presented in Figure 9. The modelled wall presents an initial higher stiffness and a sudden failure. Figure 10.a shows the numerical outlines of the specimen, Figure 10.b the state of the element at the occurrence of the first inclined crack and Figure 10.c represents the compressive stress of the wall in the point on the load-displacement diagram where it starts to decrease.

Table 3. Wall with large door cut-out comparison results [7]

WALL WITH LARGE DOOR CUT-OUT RESULTS

Element First diagonal crack Maximum lateral load imposed


Tested � = 14.13 mm drift level 317.7 kN 14.13 mm

Modeled � = 3.3 mm drift level 303 kN 5.89 mm

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Fig.10. Numerical a) S/E3wall outlines, b) 1st diagonal crack, c) compressive stress at 5.85 mm CONCLUSIONS

Analysing the numerical results it can be noted that the specimens revealed extensive cracking and concrete crushing. Under the left-side loading numerous diagonal cracks formed.

Even if there is a significant difference in the value of the occurrence of the first diagonal crack, the direction of cracking was well predicted numerically and there is also data on the thickness of the cracks which are small enough in order to not be be noticed experimentally at the beginning.

In terms of the maximum load supported by the element, the modeled wall with narrow door cut-out recorded 541.8 kN while the tested specimen had 581.8 kN.

In the case of the modelled wall with a large door cut-out the maximum load supported by the element was of 303 kN while the tested specimen had 317.7 kN.

Related to the weakening caused by the cut-out in the wall panel there is a huge load bearing capacity loss recorded for both types of door cut-out. While the solid wall panel did not fail at 1210 kN experimentally, the wall with narrow door cut-out and the wall with large door cut-out failed much earlier. In all cases, the modeled walls present an initial higher stiffness and a much earlier failure than the tested ones. Concluding upon the contribution of the numerical analysis, this was efficient from the point of view of the maximum load supported by the element and the form of cracking, sharing the same critical regions. REFERENCES 1. *** IPCT: Cl�diri de locuit P+4 din panouri mari. Proiect 770-81, Vol. D: Elemente prefabricate -

Arm�ri, Bucuresti, Romania, (1982). IPCT: Precast reinforced concrete large panel buildings P+4. Project type 770-81, Vol. D: Precast elements – Reinforcing, Bucharest, Romania.

2. DEMETER, I. (2011), Seismic retrofit of precast RC walls by externally bonded CFRP composites. PhD Thesis, Politehnica University of Timisoara.

3. *** (2010), ATENA – Advanced tool for engineering nonlinear analysis, Technical specifications 2010, Cervenka Consulting Ltd., Prague, Czech Republic.

4. DAN D., T. NAGY-GYÖRGY, V. STOIAN, A. FABIAN & I. DEMETER (2012), FRP Composites for Seismic Retrofitting of Steel-Concrete Shear Walls with Steel Encased Profiles, Stessa 2012, pp.1071-1076, Santiago, Chile.�

5. DEMETER, I., NAGY-GYÖRGY, T., STOIAN, V., and DAN, D. (2008), Quasi-static loading strategy for earthquake simulation on precast RC shear walls. Proc., 12th WSEAS International Conference on Systems, WSEAS Press, Vol.2, pp.813-819.

6. TODUT, C. (2012), Numerical modeling of RC wall panels strengthened with FRP composites, 9th fib International PhD Symposium in Civil Engineering, pp. 709-714, 22-25 July 2012, Karlsruhe, Germany.

7. TODUT, C., STOIAN, V. (2012), Numerical modeling of RC wall panels strengthened with FRP composites, 3rd Conference “Seismic Engineering and Engineering Seismology”, pp. 349-354, 22-24 May 2012, Divcibare, Serbia.

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CASE STUDY REGARDING THE INFLUENCE OF FAULTS IN EXECUTION OVER PERFORMANCE REQUIREMENTS IN A FRAME

STEEL STRUCTURE

TUNS Ioan, GALATANU Teofil-Florin*, Transilvania University of Brasov , e-mails: [email protected], * [email protected] (corresponding adress)

A B S T R A C T

Mistakes and / or imperfections of execution are in most cases to generate significant sources of strain state in structural building elements that record states of stress and strain with possible implications on the fulfillment conditions for strength, rigidity and stability components. This paper is a case study in the above mentioned context, on an in progress building, having the resistance structure made of metal frames.

Keywords: metal frame, nonconformities, node framework, structural strength, bolt


INTRODUCTION

The investigated building is located on a land outside Codlea town, in the eastern side of Brasov, on level ground, between Halchiului road and Vulcanita spring.

The studied building presented in the paper is destinated for "production facilities and administrative offices ", having the ground floor used for production purposes and the next two levels for administrative services. MATERIALS AND METHODS

The building’ resistance structure was finished when the investigation was made, having the following composition:

• Simple concrete block isolated foundations and concrete lining; • Continue foundations in the axis connecting A-E / 1; • Main frame metal structure made of span with 20m opening longitudinally between axes A /

E, rows 3-8 with a solid section steel beams (HEA 220) disposed on the end of the pole; • Metal structure made of poles and beams with the role of supporting the concrete slab at

+2.80 rate between A-E/1-3 axes; • Metal roof purlin profiles UNP 180, and horizontal bracing between A-E axes, rows 2-3 and

6-7; • Vertical bracing on the axes A and E between rows 5-6. The site is located, according our country’s macronization in terms of seismic hazard in an area

with ag = 0.20g , TC = 0.7s and the geographical characteristic value of snow load on the ground is sk,0 = 2 kPa [7] and the reference wind pressure is 0.4 kPa [8]. Stratification of the land it is so on the sole foundation level that .

For the investigated building a large number of nonconformities were found whose description is presented below:

• Free length of the bolt head failure of foundation and lack of lock nuts tightening; • Incorrect sectional shape of "joining the extension" pillars of concrete slab [6];

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• Making improper nodes of the steel structure supporting the floor (unbalanced-joints made with bolts and welding nuts loose, unrealized seams, etc.) [6].

Fig.1. Node supporting steel structure floor

• Incorrect layout and insufficient number of horizontal bracings roof; • The arrangement further perimeter foundation pillars unbalanced towards the hall; • Lack of continuous foundations in the administrative areas; • Steel structure was designed as being 100% steel S355 (OL52), but after some tests

performed on cores taken from the spot it was found that for the metal structure supporting the floor it was used S275 (OL44).

1. Structural Analysis of the Building

Studies and research have been conducted at the request of the client and consisted in an existing building advanced structural analysis using computer program in order to verify the achievement of performance requirements in terms of:

• Terms of resistance; • Terms of rigidity; • Terms of stability;

with consideration of nonconformities outlined in Section 1.2. [4, 5] Structure modeling was performed using finite element program and dimensioning of

reinforced concrete and steel structures, Advance Design. The program benefits from a separate module for calculating Advance Design Steel Connections for verifying the joints, in an interactive way, according to Eurocode 3 [9].

Elements of structural analysis developed in the three conditions are presented in the following. 1.1. Resistance exigency analysis

A major influence on the structural behavior is given by the horizontal bracing system in the plane of the roof, which plays an important role in retrieving and transmitting the horizontal task on the pillars, with a strong effect of instability on the main elements. This is the reason for proposing the analyze of the existing structural system in field in comparison with a well-conformed structure.

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a) frame from executed structure b) designed framework

Fig.2. Von Mises stress diagram on the main frame

Compared to the nominal value of the yield limit of steel which comprises the main fy = 355 N/mm2 (S355-OL52), it can be seen that in both cases the condition is fulfilled [1] [5]. Another deficiency was the development of inappropriate user nodes supporting steel structure intermediate floor at elevation +2.80, that implies the consideration of a structural design of a node with semirigid behavior. In this case we’ll have to consider the following two limit versions: node articulated and embedded [2].

a) Articulated beams in knots b) Beams embedded in knots

Fig.3. Maximum von Mises stress diagram in floor joists

The version put into execution, when node can be considered as articulated, we obtain a value of stress in the elements of resistance about twice the knotted structure that ensures continuity beams. If the maximum voltage value is articulated beams above the yield strength of steel fy = 275 N/mm2 [5]. 1.2. Requirement of stiffness analysis

Checking the condition of rigidity was done for each structural element separately for vertical and horizontal displacements. A relative movement check was made on the overall spatial structure level.

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a) Frame from executed structure b) Designed framework

Fig.4. Maximum displacement of the main frame

The check consists in comparing the relative displacement of the maximum allowable level.

Maximum displacement of the shaft was registered for the 8th ax (amounting to 59 mm), which was below the allowed value provided the norm P100/1-2006, Appendix E (amounting to 63 mm) [5].

The difference between the braced structure and the relative displacement relative to no bracings level is 32%.

Checking the rigidity of the crooked elements that make up the supporting structure bent slab consisted in checking the maximum displacement from the beam axis that was recorded for D/1-2, amounting to 11.84 mm, being below the allowed value provided, L/200 = 7150mm/200 = 35.75 mm [3].

a) Articulated beams in knots b) Beams embedded in knots

Fig.5. Maximum arrow intermediate joists

1.3. Stability requirement analysis

Braces metal structures plays an important role in the reception and transmission of the horizontal task to the pillars, with a strong effect of instability on the main elements of resistance. If the main beam lateral buckling portal frame is provided by roof panels which in turn are secured to each other with roof panels. Generally, the stability check for the elements of a structure subjected to bending and / or compression is made between two side bearing points of compressed sole.

After the structural stability calculation of the structure in the absence of the roof horizontal bracings the sectional efforts level in the roof girders does not exceed 91% of the capacity of resistance of the section, for S275 (OL52).

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The character of deformation in the higher modes of vibration and high level of horizontal bracings request indicates the insufficient horizontal bracing in the roof that is judiciously placed. Bracings current situation does not meet the minimum criteria for seismic compliance in the roof.

The column is sized to bending moment and axial force compression dominant effect on the column bending moment and axial force not. Lateral stability of the column will be provided and by rulers outsole fixed wall of the column.

If the bracing system would be done properly, the sectional efforts level in the roof girders does not exceed 83% of the capacity of resistance of the section, and if the main frame poles is 76%. This requires the arrangement of the bracings of minimum consider the composition and seismic compliance of the roof [5].

Fig.6. The maximum level of request

The sectional efforts level in special groups, the pillars supporting the floor is 97% of the

capacity of resistance of the section, for S275 (OL44). Character of deformation in the higher vibration modes requires increasing the columns rigidity by arranging building elements.

The sectional efforts level in metal beams 7.15 m of floor opening, due to local and global stability calculation reaches 101% of the capacity of resistance of the section, for steel S275 (OL44). Thus the high stress level requires increased rigidity feet high beams by arranging building elements (cover plates) between upper and lower flange.

CONCLUSIONS

The resistance condition is checked for the main structure in either executive missing braces roofing system, as well as the projected. For steel beams supporting the floor, the maximum voltage recorded for articulated beams exceed 5% value yield steel S275 (OL44).

Stiffness prerequisites for the main structure is not possible in the absence of the roof horizontal bracings, having a value exceeding 20% of the allowable set of rules. For steel beams from floor deflection value is increased about five times in front of the articulated version at which the nodes are continuous.

Checking the stability of the main structural elements can not be done only by making a proper bracing system which can reduce sectional efforts up to 15%. Floor beams supporting the

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opening of 7,15 m, sought-buckling bending to the side, not the condition of stability than by making connections between top flange and bottom flange fixed to the concrete slab.

Following checks carried out on structural elements and overall building, looking to meet the demands of strength, rigidity and stability have been highlighted and remedial measures to strengthen the nonconformities found.

They refer to: - Assessment and remediation of the end of the fixing bolts in the foundation pillars; - Check and correct the continuity in supporting floor structure nodes at level 2.80 m; - Strengthening the section of "joint extension" pillars supporting the floor; - Hardening pillars at the rate of 2.80 m slab; - Hardening of the floor beams supporting the opening of 7,15 m - Filling and judicious arrangement of horizontal bracing elements of the roof.

As a result of the study concluded that although efforts obtained after introduction nonconformities found significantly increased efforts unitary structure were analyzed and over the allowable limit. REFERENCES 1. DUBINA, D., RONDAL, J., and VAYAS, B. (1997), Calculul Structurilor Metalice-Eurocode 3,

(Design of Steel Structures-Eurocode 3), CME TEMPUS, Timisoara. 2. GALATANU, T., CIONGRADI, I.,P., BUDESCU, M., and ROSCA, O., Experimental studies of the

back-to-back connected cold formed steel profile bolted joints, The Bulletin of the Polytechnic Institute of Jassy, Construction. Architecture Section, LV(LIX), f.1, pp. 17-28, 2009.

3. MOGA, P., PACURARU , V., GUTIU, S., MOGA, C. (2006), Proiectarea structurilor metalice. Norme romane - Eurocod 3, (Design of Steel Structures. Romanian norms - Eurocod 3) Editura U.T. Pres, Cluj-Napoca.

4. ***(2006), SR EN 1991-1-1/NA: Ac�iuni asupra structurilor. Partea 1-1: Ac�iuni generale – Greut��i specifice, greut��i proprii, înc�rc�ri din exploatare pentru construc�ii. Anexa na�ional�, (Actions on structures. Part 1-1: General actions – Densities, self-weight, imposed loads for buildings. National Annex), ASRO.

5. *** (2006), SR EN 1993-1-1: Proiectarea structurilor din otel. Partea 1-1: Reguli generale �i reguli pentru cl�diri, (Design of steel structures. Part 1-1: General rules and rules for buildings), ASRO.

6. *** (2006), SR EN 1993-1-8: Proiectarea structurilor din o�el. Partea 1-8: Proiectarea îmbin�rilor, (Design of steel structures. Part 1-8: Design of joints), ASRO.

7. *** (2005), CR 1-1-3: Cod de proiectare. Evaluarea ac�iunii z�pezii asupra construc�iilor, (Design code. Snow loads on buildings), ASRO.

8. *** (2004), NP-082: Bazele proiect�rii �i ac�iuni asupra construc�iilor. Ac�iunea vântului, (Actions on structures. Wind actions.), ASRO.

9. *** (2006), Manual de utilizare – Advance Design, (Use manual – Advance Design), GRAITEC, Bievres.

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AUTHORS INDEX

Boeriu Lucia-Maria

Ph.D.Lecturer Eng., Transilvania University of Brasov, Romania, e-mail: [email protected]

Bota Adrian Assoc. Prof. Ph.D., Bridge Department, Civil Engineering Faculty, "Politehnica" University of Timisoara, Romania, tel. +40723334179, e-mail: [email protected]

Budescu Mihai Technical University “Gheorghe Asachi” of Iasi, Romania, e-mail: [email protected]

Cazan Oana

Technical University of Cluj-Napoca, Romania

Cîrstolovean Ioan Lucian Ph.D. Lecturer Eng., University Transilvania Brasov, Faculty of Building Engineering, Romania, e-mail: [email protected]

Chira Alexandru Technical University of Cluj-Napoca, Romania

Demeter István Politehnica University of Timi�oara, Romania, e-mail: [email protected]

F�rca� Anagabriela

Ph.D. Student Junior Assistant Eng., Technical University of Cluj-Napoca, Romania, e-mail: [email protected]

Galatanu Teofil-Florin Transilvania University of Brasov, Romania, e-mail: [email protected]

Gaman Florian Ph.D. Associate Professor Eng., Technical University of Civil Engineering Bucharest, Faculty of Civil, Industrial and Agricultural Engineering, Department of Civil, Urban Engineering and Technology, Romania, e-mail: [email protected]

Iacoboaea Cristina Ph.D. Lecturer Eng., Technical University of Civil Engineering Bucharest, Faculty of Civil, Industrial and Agricultural Engineering, Department of Civil, Urban Engineering and Technology, Romania, e-mail: [email protected]

Iona�cu Anamaria Technical University of Civil Engineering Bucharest, Romania, e-mail: [email protected]

Jocea Andreea Florina

Ph.D. Teaching Assistant Eng., Technical University of Civil Engineering of Bucharest, Romania,e-mail: [email protected]

Luca Oana Ph.D. Associate Professor Eng., Technical University of Civil Engineering Bucharest, Faculty of Civil, Industrial and Agricultural Engineering, Department of Civil, Urban Engineering and Technology, Romania, e-mail: [email protected]

M�gurean Cornelia Ph.D.Prof.Eng., Technical University of Cluj Napoca, Department of Structures, Romania, e-mail: [email protected]

Mizgan Paraschiva Ph.D. Lecturer Eng., University Transilvania of Brasov, Romania, e-mail: [email protected]

Moldovan Radu

Ph.D. Student Eng., Technical University of Cluj-Napoca, Romania, e-mail: [email protected]

Nari�a Alina-Maria

“Politehnica” University of Timisoara, Romania, e-mail: [email protected]

Mo�oarc� Marius Ph.D. Lecturer Eng., “Politehnica” University of Timisoara, Faculty of Architecture, Romania, e-mail: [email protected]

Muscalu Marius-Teodor Postdoctoral Researcher, Ph.D. Eng., Technical University “Gheorghe Asachi” of Iasi, tel. +40742004970, Romania, e-mail: [email protected]

Nagy-György Tamás Ph.D. Lecturer Eng., Politehnica University of Timisoara, Romania, e-mail: [email protected]

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Puia Mihaela Simina National Agency of Cadastre and Land Registration, tel. Tel: +40745264179, Romania, e-mail: [email protected]

Radu Andrei Technical University “Gheorghe Asachi” of Iasi Romania, e-mail: [email protected]

Radu Dorin University of “Transilvania Brasov” Faculty of Civil Engineering, tel. +40721126161, Romania, e-mail: [email protected]

Rus Tiberiu Technical University of Civil Engineering Bucharest, Romania, e-mail: [email protected]

Sandor Florin Ph.D. Student Eng., Technical University of Cluj-Napoca, Romania, e-mail: [email protected]

Stoian Valeriu Ph.D. Professor, Politehnica University of Timisoara, Romania, e-mail: [email protected]

T�ma� Florin-L. Transilvania University of Bra�ov,Romania, e-mail: [email protected]

Todu� Carla Politehnica University of Timi�oara, Romania, e-mail: [email protected]

Tuns Ioan Transilvania University of Bra�ov, Romania, e-mail: [email protected]

��ranu Nicolae Technical University “Gheorghe Asachi” of Iasi, Romania, e-mail: [email protected]

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