PSZ 19:16(Pind.l /97)UNIVERSITI TEKNOLOGI MALAYSIA

BORANG PENGESAHAN STATUS TESIS ·

JUDUL : REPAIR AND STRENGTHENING METHODS FORBRIDGE SUPPORTS

SESI PENGAJIAN : 2006/2007

Saya HANIZAH BINTI ARGADAN

(HURUF BESAR)

mengaku membenarkan tesis (PSMISatjana/Dekter Falsafah)* ini disimpan di PerpustakaanUniversiti Teknologi Malaysia dengan syarat-syaratkegunaannya seperti berikut :

1. Tesis adalah hak milik Universiti Teknologi Malaysia.2. Perpustakaan Universiti Teknologi Malaysia dibenarkan membuat salinan untuk tujuan

pengajian sahaja.3. Perpustakaan dibenarkan membuat salinan tesis ini sebagai bahan pertukaran antara

institusi pengajian tinggi4. **Sila tandakan ( ,/ )

D SULIT

D TERHAD

(Mengandungi maklumat yang berdatjah keselamatan ataukepentingan Malaysia seperti yang termaktub di dalamAKT A RAHSIA RASMI 1972)

(Mengandungi maklumat TERHAD yang telah ditentukanoleh organisasilbadan dimana penyelidikan dijalankan)

o TIDAK TERHAD

tJl~(TAND ATANGAN PENULIS)

Alamat Tetap:NO.51OBLOK A GUGUSAN MELATIJALAN CAMAR 4/5 SEKSYEN4KOTADAMANSARA47810 PETALING JAYA. SELANGOR

Tarikh: 0"5 ~ ~4.

PROF. DR. AZLAN BIN ABD. RAHMAN

Nama Penyelia

Tarikh :

CATATAN: *

.

Potong yang tidak berkenaan.** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak

berkuasalorganisasi berkenaan dengan menyatakan sekali sebab dantempoh tesis ini perlu dikelaskan sebagai SULIT atau TERHAD.Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah dan Sarjanasecara penyelidikan, atau disertasi bagi pengajian secara kerja kursus danpenyelidikan, atau Laporan Projek Satjana Muda (PSM).

"I hereby declare that I have read this thesis and in

my opinion this thesis is sufficient in terms of scope and quality

for the award of the degree of Master of Engineering (Civil-Structure)"

Signature

Name of Supervisor

Date

11

I declare that this thesis entitled "Repair and Strengthening Methods for Bridge

Supports" is the result of my own research except as cited in the references. The

thesis has not been accepted for any degree and is not concurrently submitted in

candidature of any other degree.

Signature

Name

Date

HANIZAH BINTI ARGADAN

O~ \'(\e ~1"

iv

ACKNOWLEDGEMENT

I wish to express my gratitude to those who contributes in the preparation and

completion of this project dissertation especially to:

Government of Malaysia for providing the financial support during the course

of this work;

My supervisor, Prof. Dr. Azlan b. Abdul Rahman for all the useful comments

and suggestions for the completion of this project

Ir. Abdul Hadi Jusoh, Pn. Sherliza Zaini Sooria and Mr. Lee Choon Shiang,

form Jabatan Kerja Raya for providing the information and access to the project site;

My superior, Ir. Mohd Noor Azudin b. Mansor from Jabatan Kerja Raya for

his understanding during the whole duration of my study and for his invaluable

assistance in the preparation of this dissertation;

Noraidah Yahya, for her kind co-operation and full encouragement in entire

period of my study and for her ideas in the preparation of this dissertation;

Last but not least, to my beloved family for their pray, support and patience.

iii

To my beloved parents

v

ABSTRACT

This project dissertation paper is a study on the repair and strengthening

method for the support of a flyover affected by structural cracks. The study focuses

on the techniques used to structurally repair or strengthen the concrete bridge piers of

the selected case study involving the combination of external pre-stressing and

composite method. Factor and requirement for repair and strengthening of the bridge

supports have been reviewed whereby the technical aspects with respect to structural

strength are studied. A hypothetical detail of bridge support has been created and

investigated to study the effect on the flexural capacity of concrete section when pre-

tensioning force imposed the CFRP strip prior to the adhesion of the plate onto the

concrete bridge support. A general flow of repair and strengthening of concrete

bridge support has been developed based on the analysis of the case study and results

of the section analysis of the hypothetical detail. It is found that the choice of repair

and strengthening method of bridge supports required a comprehensive structural

investigation, careful design and construction. Data of the existing structure and its

material properties, as well as the innovative approach of the construction technique

are important factors for a successful implementation of the repair / strengthening

method. In this particular case study, the repair and strengthening scheme which

utilized a combination of external pre-stressing and composite system has been

successfully applied to the bridge supports. Continuous monitoring and maintenance

are required to ensure that the repair is effective in providing the solution to the

structural problem.

vi

ABSTRAK

Disertasi ini adalah untuk mengkaji teknik pembaikan dan penguatan sokong

jambatan yang mengalami keretakan. Kajian ini dijalankan dengan memilih kajian

kes dan memfokuskan terhadap teknik pembaikan dan penguatan sokong jambatan

secara struktur. Faktor-faktor dan keperluan untuk membaiki dan menguatkan

sokong jambatan telah dikaji dengan memberikan tumpuan kepada aspek kekuatan

struktur. Satu butiran hipotesis sokong telah dibentuk untuk mengkaji kesan daya

pra-tegangan terhadap kekuatan lenturan muktamad keratan konkrit apabila daya pra-

tegangan dikenakan kepada kepingan CFRP sebelum kepingan tersebut dilekatkan ke

permukaan sokong konkrit. Satu carta aliran umum berkenaan tatacara pembaikan

dan penguatan sokong jambatan konkrit telah dirangka berdasarkan kajian kes dan

hasil analisis keratan butiran hipotesis tadi. Adalah didapati bahawa pemilihan cara

pembaikan dan penguatan memerlukan penyiasatan struktur yang komprehensif serta

rekabentuk dan pembinaan yang teliti. Data untuk struktur sediada dan sifat bahan di

samping pendekatan inovatif dalam teknik pembinaan adalah faktor-faktor penting

untuk perlaksanaan kaedah pembaikan dan penguatan yang berjaya. Dalam kajian

kes ini, skim pembaikan dan penguatan yang mengunakan gabungan pra-tegasan

luaran dan sistem komposit telah didapati berjaya diaplikasikan untuk sokong

jambatan. Pemantauan dan penyelenggaraan yang berterusan terhadap kaedah

pembaikan tersebut adalah diperlukan untuk memastikan bahawa ianya berkesan

dalam penyelesaian sesuatu masalah struktur.

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TABLE OF CONTENT

CHAPTER TITLE PAGE

DECLARATION ii

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENT vii

LIST OF TABLES x

LIST OF FIGURES xi

LIST OF SYMBOLS xiv

LIST OF APPENDICES xvii

1 INTRODUCTION 1

1.1 Significance of Study 2

1.2 Objective of Study 3

2 LITERATURE REVIEW 4

2.1 Bridge Support 4

2.2 Structural Concrete repair 5

2.2.1 Concrete Cracks 6

2.2.2 Crack Repair Method and Material 6

2.3 Structural Strengthening 12

2.3.1 Steel-base Strengthening Material 12

2.3.2 FRP-base Strengthening Material 15

viii

2.4 External pre-stressing Strengthening 19

2.4.1 Flexural Section Analysis 20

2.5 CFRP Strip Flexural Strengthening 22

2.5.1 Level of Post Tensioning 23

2.5.2 Pre-stressed or Post-Tensioned 27

CFRP Strips

2.5.3 Force Transfer from Strip to 28

Dead and Live Anchors

2.5.4 Force Transfer from Dead or 30

Live Anchor to Concrete

3 METHODOLOGY 32

3.1 Hypothetical Bridge Support Detail 32

3.1.1 Detail of Existing Section 33

3.1.2 Detail of Strengthen Section 35

3.2 Ultimate Section Capacity 37

3.2.1 Existing Section 37

3.2.2 Strengthen Section 40

3.3 Case Study Selection 45

3.4 General Flow of Bridge Support 45

Repair and Strengthening

4 ANALYSIS AND DISCUSSION 46

4.1 Pier Head Existing Section Capacity 46

4.1.1 Flexural Capacity in Longitudinal Direction 47

4.1.2 Transverse Capacity of Existing Section 48

4.2 Strengthen Section Capacity 48

4.2.1 Flexural Capacity in Longitudinal Direction 48

4.2.2 Transverse Capacity of Strengthen Section 50

ix

5 CASE STUDY: Repair and Strengthening of Middle Ring Road 52

(MRR2) Package 11

5.1 Introduction 52

5.1.1 Description of the Structure 52

5.1.2 Background of the Problem 54

5.2 Description of Repair and Strengthening Work 56

5.2.1 Detail of Repair and Strengthening 56

5.2.2 Stages of Repair and Strengthening 59

5.3 Conclusion 63

6 General Guideline for Repair and Strengthening Concrete 64

Bridge Support

6.1 Introduction 64

6.1.1 Existing Bridge Support Assessment 64

6.1.2 Conceptual Stage 65

6.1.3 Detail Analysis and Design 66

6.1.4 Construction Stage 67

6.1.5 Service Stage 68

6.2 Flow Chart of Repair and Strengthening Guideline Process 68

7 CONCLUSIONS AND RECOMMENDATIONS 70

7.1 Conclusions 70

7.2 Recommendations 71

REFERENCES 73-75

Appendix A-B: 76-101

x

LIST OF TABLES

TABLE NO TITLE PAGE

2.1 Mechanical / physical properties of adhesive - Sikadur 30 10

2.2 Mechanical / physical properties of epoxy resin

Sikadur 31LP 11

2.3 Pre-stressing bar properties, (Dwidag System International) 15

2.4 Properties for carbon fibres (Sika CarboDur Plate) 18

2.5 Values of partial factors for FRP material 19

3.1 Reinforcement area for existing pier Crossbeam 34

3.2 Material properties for existing section 35

3.3 Technical properties of CFRP strip for strengthening 35

3.4 Technical properties of Dywidag Post Tensioning system

using bar 36

xi

LIST OF FIGURES

FIGURE NO TITLE PAGE

2.1 Stress-strain curves, (Collins and Mitchell 1991) 14

2.2 Properties of different fibre and KsSteel. After

ACI Comitee 440 and Dejke (2000) 16

2.3 Stress-Strain diagram for Sika CarboDur 17

2.4 Stress Strain Diagram for external pre-stressing 20

2.5 Failure mechanism of beams strengthened with bonded

CFRP strips with respect to the level of post-tensioning 23

2.6 Shear stress distribution inside the final anchorage induced

by rear-loading of prestressing force V (τV), front-loading

of additional forces ∆Z (τ∆Z) and its superposition (τV+∆Z) 29

2.7 Transfer of pre-stressing force from anchor to concrete 30

3.1 Existing bridge support reinforcement and plan view 34

3.2 Strengthen bridge support and plan view 36

3.3 Stress-strain diagram for the existing section 38

xii

3.4 Stress-strain diagram for the strengthen section over beam depth 40

4.1 Schematic presentation for Length vs. Moment of Resistance 50

5.1 Location map of Middle Ring Road 2 Package 11 53

5.2 Location map of Middle Ring Road 2 Package 11 (Close View) 53

5.3 Sketch of Location map for Middle Ring Road 2 Package 11 54

5.4 Stages of repair and strengthening 60

5.5 Predicted stress condition at service 61

5.6 Predicted stress condition at the application of external

pre-stressing force form the steel tie frame

(Prior to the closure of cracks) 61

5.7 Predicted stress condition at the application of external

pre-stressing force form the steel tie frame

(After the closure of cracks) 62

5.8 Predicted stress condition at the application of external

pre-stressing force form the steel tie frame

and the CFRP Plate 62

5.9 Predicted stress condition after the released of external

pre-stressing force in the steel tie frame 62

5.10 Predicted stress condition at service after strengthening

process (With assumption class 3 pre-stressing concrete

member is obtained) 63

xiii

6.1 Schematic representation of repair and strengthening

process for bridge support with strength failure 69

xiv

LIST OF SYMBOLS

a - Shear span or distance from beam support to the nearest loading point

Ac - Gross section area of concrete section

A’c - Area of crack concrete section

Aps - Area of external tendon

As, Asi - Area of internal steel reinforcement

bc, b - Width of beam

c, x, - Neutral axis

dfrp - Depth of FRP

fc’ - Cylinder compressive strength of concrete

fcu - Concrete ultimate strength (Concrete grade)

fpe - Effective tendon pre-stress

fps, - Stress in external tendon

fsi, σsi - Stress in internal steel

fy - Ultimate strength for steel (Steel yield stress)

Fc - Compression strut

Ft - Tension tie

Fs - Pre-stress force tie

d - Effective depth of un-strengthened section (with respect to steel)

dpso,du - Effective tendon depth at ultimate

Efrp - Modulus of elasticity for FRP

e - Eccentricity of steel tie frame

e’ - Eccentricity of CFRP strip

Est - Modulus of elasticity for steel

h - Overall beam height

k1 - The mean stress factor

xv

k2 - Concrete compressive force centroid factor

ks - Second order effect

L - Beam span

Lu - Horizontal distance between end of the pre-stress tensioning strands

Ms - Service moment during construction

M’s - Additional service moment after the release of steel tie frame

Mu - Ultimate Flexural strength of strengthen beam

Mun - Ultimate flexural strength of un-strengthen beam

Pi - Initial pre-stressing force in CFRP

P’st - Portion of pre-stressing force from the steel tie frame

Prup - CFRP rupture strength

Pst - Total effective pre-stressing force from the steel tie frame

xcr - The critical depth of neutral axis of strengthened section

x1, x2 - The depth of neutral axis of the section which takes into consideration

the curve shape of pier crossbeam

T - The applied horizontal load along with

V - Vertical force

Zb - Section modulus for bottom fibre of un-crack concrete section

Zt - Section modulus for bottom fibre of un-crack concrete section

Z’b - Section modulus for bottom fibre of crack concrete section

Z’t - Section modulus for top fibre of crack concrete section

Zcb - Section modulus for bottom fibre of composite section

Zct - Section modulus for bottom fibre of composite concrete section

z - Lever arm of concrete section

β - Estimated loses in pre-stressing of CFRP

β - Compression stress block depth factor to ACI Building Code

(ACI Committee 1999)

εco - The compressive strain of unconfined concrete, at the peak

stress of concrete

εcf - Strain in concrete

εcu - Ultimate strain of concrete

εfrp - Strain in FRP

εfrp-rup - Strain in FRP at rupture for composite section

εfrp-ini - Initial strain in FRP

xvi

εfrp-max - Maximum strain in FRP

εsi - The strain in the steel

γc - Partial safety factor material (concrete) safety factor

γmwE - Partial safety factor for the modulus of the fibres in tension and

compression

γmwy - Partial safety factor for the compressive strength of the fibres

γmwε − Partial safety factor for the strain capacity of the fibres in tension and

compression and the strain at ‘failure’ in the fibres in compression.

ρfrp - The ratio of CFRP

ρfrp-cr - The critical ratio of CFRP

σc - Stress in concrete before strengthening

σ'c - Stress in concrete after strengthening

σfrp - Stress in FRP

ρsi - The ratio of internal steel

Ωu - Bond reduction coefficient at the ultimate limit state

xvii

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Pictures on Repair and Strengthening Works

of Middle Ring Road, (MRR2) Package 11 76-90

B Result for Hypothetical Bridge Support

Analysis 91-101

CHAPTER 1

INTRODUCTION

Bridge generally needs structural modification when there is insufficiency

strength caused by design inadequacies, incorrect detailing, improper construction or

loss of stiffness due to material deterioration. Sometimes combination of these

factors exists. The most common methods of structural modification are in the form

of repairing, stiffening or strengthening the existing structure. Strengthening and

stiffening are also necessary due to increase in live load and design code revision.

Failure in serviceability limit state attracts concern from the public. The

safety of public facilities and infrastructure always become an issue when there is

apparent concrete crack, excessive deflection and unacceptable vibration. Occurrence

of this symptom is also the warning to the ultimate safety of a structure. As for

bridge, these symptoms need particular repair or strengthening method to reinstate

the bridge to it original service level.

Bridge support; the pier, pier cap and abutment, are considerably important to

be maintained, repaired and strengthened where necessary. Damage of bridge

support that is not repaired or strengthened properly would affect the bridge integrity

as a whole.

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When reconstruction or demolition is not an option, innovation in method of

structural repair or strengthening should be the solution. However, repair and

strengthening method need to consider a suitable theoretical background for a

successful scheme. Cause of failure, existing condition of structure, the material

compatibility and constructability are all equally important in short listing the

possible solutions for repair or strengthening a structure. For concrete bridge

structure whether by attaching the repair material directly onto the concrete surface

to form composite, crack grouting or reinstating the structure via external pre-

stressing, must undergo proper evaluation and selection.

Recent development in advanced civil engineering material provides variety

of options for repair technique to suit the required condition of a deficient structure.

Furthermore, the cost factor must be taken into consideration and in most cases this

is the major determining factor.

1.1 Significance of Study

The study provides more evidence on the applicability of the existing

theoretical background for repair and strengthening of bridge superstructure.

Compiling the state-of-the-art technology in repair, stiffening and strengthening of

bridge support provides a possibility for improvement of the existing engineering

judgements or assumption made in designing the bridge repair and strengthening. If

the technical aspects in state-of-the-art-technique such as safety factor, material

mechanical properties, and static mechanic involves as well as the suitable

assumptions made in bridge support modification work is continuously collected, a

general guidelines for structural repair, stiffening and strengthening of bridge support

is possible. Furthermore, through a case study, the necessary measure or good

engineering practices adopted during the process of modification of bridge support

can be documented. This is important to identify what are the do’s and don’ts during

3

the repair and strengthening work for an acceptable level of performance and

durability of the repair material and the modified bridge support as a whole.

2.1 Objective of Study

The objective of this case study is to review the factors and requirements for

strengthening of concrete bridge support. The study will also investigate the

technical aspects of strengthening techniques for concrete bridge support through a

selected case study.