Connection Design According to en 1993 Part 1-8 -

Helsinki University of Technology Laboratory of Steel Structures Publications 33

Teknillisen korkeakoulun teräsrakennetekniikan laboratorion julkaisuja 31

Espoo 2007 TKK-TER-33

DESIGN OF STRUCTURAL CONNECTIONS TO EUROCODE Preview of MS Power Point presentations

F. Wald

AB TEKNILLINEN KORKEAKOULUTEKNISKA HÖGSKOLANHELSINKI UNIVERSITY OF TECHNOLOGYTECHNISCHE UNIVERSITÄT HELSINKIUNIVERSITE DE TECHNOLOGIE D’HELSINKI

1

Introduction

Lessons Connection Design according to EN 1993-1-8

Prof. František WaldCzech Technical University in Prague

2

List of Lessons at Seminar1. Introduction2. Bases of design according to EN 1993-1-83. Welded connections4. Bolted connections5. Basics of structural joints6. Design of simple connections 7. Column bases8. Fire design of connections, EN 1993-1-29. Seismic design, EN 1998-1-1

3

SummaryList of contentTiming National Annexes CeStruCoAccess STEELSummary

CeStruCo

in Window Help Formatwith PP Presentations

Lessons

4

List of Content in EN 1993-1-81. Introduction2. Basis of design3. Connections made with bolts, rivets or pins4. Welded connections5. Analysis, classification and modelling6. Structural joints connecting H or I sections7. Hollow section joints

5


CeStruCo


Lessons

6

Development of EurocodesECCS Concept in 1978ECCS First draft in 1984CEN Started with Eurocodes in 1990CEN ENV 199x-x-x in 1992 (actions nationally only)CEN EN 199x-x-x in 2005

AdvantagesEuropean agreementAll structural materials under one safety concept

WeaknessCopyrightsSize (some countries only rules, some textbooks)

7

List of EurocodesEN 1990 Eurocode 0: Basis of Structural Design EN 1991 Eurocode 1: Actions on structuresEN 1992 Eurocode 2: Design of concrete structuresEN 1993 Eurocode 3: Design of steel structures

Project team Prof. F. Bijlaard

EN 1994 Eurocode 4: Design of composite steel and concrete struc.Project team Prof. D. Anderson

EN 1995 Eurocode 5: Design of timber structuresEN 1996 Eurocode 6: Design of masonry structuresEN 1997 Eurocode 7: Geotechnical designEN 1998 Eurocode 8: Design of structures for earthquake resistanceEN 1999 Eurocode 9: Design of aluminium structures

8

Eurocodes List of ActionsEN 1991-1-1 Actions – Dead load published 04/02EN 1991-1-2 Actions – Fire 11/02EN 1991-1-3 Actions – Snow 07/03EN 1991-1-4 Actions – Wind 04/05EN 1991-1-5 Actions – Temperature 11/03EN 1991-1-6 Actions – During erection 06/05EN 1991-1-7 Actions – Exceptional 05/06EN 1991-2 Actions – Transport on bridges 09/03EN 1991-3 Actions – Crane girders 11/06EN 1991-4 Actions – Silos and tanks 08/05

9

Structural Steel Eurocodes (20 documents)EN 1993-1-1 Basic rules First package 05/05EN 1993-1-2 Fire resistance 04/05EN 1993-1-3 Thin walledEN 1993-1-4 Corrosion resistantEN 1993-1-5 PlatesEN 1993-1-6 ShellsEN 1993-1-7 Plates 2EN 1993-1-8 Connections 05/05EN 1993-1-9 Fatigue 05/05EN 1993-1-10 Brittle fracture 05/05EN 1993-1-11 Tensile members (cables)EN 1993-1-12 HSSEN 1993-2 BridgesEN 1993-3-1 MastEN 1993-3-2 ChimneysEN 1993-4-1 SilosEN 1993-4-2 TanksEN 1993-4-3 PipelinesEN 1993-5 PilotsEN 1993- 6 Crane girders

10

Development of EN 1993-1-8From ENV 1991-1 Chapter 6 Connections

Annex J JointsAnnex L Base platesAnnex K Hollow section joints

ECCS TC10 comments to ENV 1993-1-1 May 12, 1992CEN/TS250/SC3 project team, head Mr. Jouko Kouhi VTT, FinlandprEN 1993-1-8 document N 1054 E Sept. 9, 2001900 national commentsFinal draft Nov. 20, 2001Voting April 16, 2004Acceptation by CEN May 11, 2005

11

Eurocode Implementation - ExamplesTranslationsUK N/A; France 12/2006; Poland 2007; Czech Rep. 8/2006

National AnnexesUK 12/2007; France 12/2006; Poland 2010; Czech Rep. 8/2006

Eurocodes be adopted for government constructionUK unknown; France Not; Poland 2010; Czech Rep. 2008

Eurocodes be adopted for non-government constructionUK unknown; France Not; Poland 2010; Czech Rep. 2008

National standards withdrawnUK 2010; France 2010; Poland 2010; Czech Rep. 2010

12

SummaryList of contentTiming National Annexes CeStruCoAccess STEELConclusions

CeStruCo


Lessons

13

National Annex for EN 1993-1-8Alternative proceduresNationally Determined Parameters

National choice is allowed in EN 1993-1-8 through (only):1.2.6(6) Reference standard Rivets2.2(2) Partial safety factors3.1.1(3) Bolt classes 3.4.2(1) Hand tightening of the nut is considered adequate 5.2.1(2) Classification of joints 6.2.7.2(9) Requirements for elastic distribution of forces in bolt rows

14

National Choice (Czech Rep.)Clause 1.2.6 Reference Standards, Group 6: Rivets

ČSN 02 2300: Rivets, Overview (Czech national standards).Clause 2.2 Partial safety factors, paragraph (2)

Numerical values of partial safety factors for joints are not changed, the valuesin Table 2.1 should be used.

Clause 3.1.1(3) General, paragraph (2)All bolt classes listened in Table 3.1 may be used.

Clause 3.4.2 Tension connections, paragraph (1)If the preload is not explicitly required in design for slip resistance, the hand tightening of the nut is considered adequate without the control of preload.

Clause 5.2.1 General, paragraph (2)No additional information on classification of joints by their stiffness and strength are given to that included in 5.2.1(2).

Clause 6.2.7.2 Beam-to-column joints with bolted end-plate connections, paragraph (9)

The requirements for elastic distribution of forces in the bolt rows introducedin (6.26) are not changed.

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CeStruCo


Lessons

16

CeStruCo =Civil enginnering Structural Connections

Aristotle University of Thessaloniki, GreeceBouwen met Staall, NetherlandsBuilding Research Establishment Ltd., United KingdomCzech Technical University (contractor), Czech RepublicLuleå University of Technology, SwedenUniversity of Coimbra, PortugalPolitechnica University of Timisoara, Romania

ReviewKREKON Design office, Rotterdam, Netherlands Czech EXCON a.s., Prague, Czech RepublicConstructional Steelwork Association Ostrava, CR

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European Educational ProjectsESDEP Basic European educational projectWIVISS CD lessonsSteelCall Virtual officeStainless SteelCall Internet/CDSSEDTA PP presentation + lessonsCeStruCo Connection designNFATEC Internet coursesSDCWASS Austenitic stainless steelDIFISEK Fire design

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Textbook1. Introduction 2. Bolts 3. Welding 4. Structural Modelling 5. Simple Connections 6. Moment Resistance Connections7. Column Bases8. Seismic Design9. Fire Design10. Hollow Section Joints11. Cold-Formed Member Joints12. Aluminium Connections13. Design Cases

19

Internet / CD VersionLessons in Window help formatTextbook in PDF fileWorked examplesPresentations

PowerPointProgramme „Nonlinear analyses of joints by component method“Video film

Tools for connection designExample of SoftwareExample of Tables

20

Lessons in Window Help Format

Prepared by RoboHelp tool at Czech Technical University in Prague

21

PowerPoint Presentations

Based on Fire test on 8th storey building Cardington, January 16, 2003 22

Software

Non-linear Analysis of Steel ConnectionsCoimbra UniversityPrediction of behaviour by component method with nonlinear force - deformation diagram of components

23

Video Film

Statically Stressed Bolts in Dynamically Loaded Connectionsprepared at Delft University

24

CeStruCo on CD

Educational material to support conversion of ENV 1993-1-1 to EN1993-1-8

CD / Internet lessons

www.fsv.cvut.cz/cestrucoCeStruCo


Lessons

25


CeStruCo


Lessons

26

Access STEEL – Informational tool at www.access-steel.com

27

Access STEEL – Information SystemEurocodes 1993-1-x and EN 1994-1-x for not steel specialists

Project Initiation Scheme Development Detailed Design Verification

For practising designers, architects and their clientsDetailed design of elementsStep-by-step guidanceFull supporting information Worked examplesInteractive worked examples

English, French, German and SpanishProject of EU eContent Programme

28

Access STEEL - DocumentsTopics

Multi-storey Buildings Single Buildings Residential Construction

Fire Safety Engineering

250 separate technical resources + 50 interlinked modules Client's guideConcept designsFlow Charts

Non-conflicting Complementary InformationWorked examples (Pasive and Interactive)

29

Example - Client's Guide

30

Example - Concept Designs

31

Example - Flow Charts

32

Example - Non-Conflicting Complementary Information

33

Example – Pasive Worked Example

34

Example – Interactive Worked Example

35

Access STEELInformational system based on hypertext engine

36

SummaryEN 1993-1-8 – Connectors and jointsEN 1993-1-8 – Will be used from 2007 (mostly)

CeStruCo – Educational material to EN 1993-1-8 Access STEEL – Informational tool for EC3 on internet

1

Bases of Designaccording to EN 1993-1-8


Prof. František Wald

2


3

TopicsBases of DesignEccentricity at IntersectionsConnection Modelling in Global AnalysesGlobal Analysis of Lattice GirdersClassification of JointsModelling of Beam-to-Column Joints Summary

4

General RequirementsAll joints should have a design resistance such that the structure is capable of satisfying all the basic design requirements given in EN 1993-1-1.

5

Effect of actionsResistance

Frequency bar chart

Partial safety factors for jointsResistance of members and cross-sections γM0, γM1, γM2

Resistance of bolts, rivets, pins, welds, plates in bearing γ M2

Slip resistance γ M3, γ M3,ser

Bearing resistance of an injection bolt γ M4

Resistance of joints in hollow section lattice girder γ M5

Resistance of pins at serviceability limit state γ M6,ser

Preload of high strength bolts γ M7

Recommended valuesγ M2 = γ M3 = 1,25 (EN 1993-1-1 γ M0 = 1,00, γ M1 = 1,10) γ M3,ser = γ M7 = 1,10γ M4 = γ M5 = γ M6,ser = 1,00

6

Applied Forces and MomentsThe forces and moments applied to joints at the ultimate limit state should be determined according to the principles in EN 1993-1-1.

7

Resistance of JointsOn the basis of the resistances of its basic components

Linear-elastic or elastic-plastic analysis

Fasteners with different stiffnessesWith the highest stiffness should be designed to carry the load. (An exception bolts and slip resistant bolts).

8


9

Eccentricity at IntersectionsThe joints and members should be designed for the resulting moments and forces

Except in the case of particular types of structures - lattice girdersIn the case of joints of angles or tees attached by either a single line of bolts or two lines of bolts

Centroidal axes

Setting out lines

Fasteners

Fasteners

10

Reduction of Resistance of Angles Connected by One Leg(and other unsymmetrically connected members in tension)

Reduction factors Pitch p1 < 2,5 do > 5,0 do 2 bolts β2 0,4 0,7 3 bolts or more β3 0,5 0,7

With 1 bolt: Nu,Rd = 2

02 )5,0(0,2

M

uftdeγ−

With 2 bolts: Nu,Rd = 2

2

M

unet fAγ

β

With 3 or more bolts: Nu,Rd = 2

3

M

unet fAγ

β

11


12

Types of Joint Modelling

Simple--Pinned

-Semi-continuousSemi-continuousSemi - rigid

-Semi-continuousContinuousRigid

PinnedPartial-strengthFull-strength

RESISTANCESTIFFNESS

13

Elastic analysis at the Serviceability Limit StateDesign joint properties based on the type of global analysis

Initial stiffness Sj,ini and resistance Mj.Rd

M

Mj,Rd

j,Sd

23

Sj,ini

M

φ

14

Elastic analysis at the Ultimate Limit StateModified stiffness Sj,ini and resistance Mj,Rd

η is stiffness modification coefficient

M

Mj,Rd

j,Sd S / j,ini

M

φ

η

S j,ini

15

Stiffness Modification Coefficient η

3-Base plates3,52Bolted flange cleats32Bolted end-plates32Welded

Other types of joints (beam-to-beam joints, beam splices, column

base joints)

Beam-to-column jointsType of connection

M

Mj,Rd

j,Sd S / j,ini

M

φ

η

S j,ini

16

Rigid - Plastic AnalysisResistance Mj,Rd and deformation capacity φCd

M j,Rd

M

φφCd

17

Elastic - Plastic AnalysisFull curve description

M j,Rd

M

φφCd

S j,ini

18

Joint Modelling and Frame Global Analysis

PinnedPinnedPinnedSimple

Rigid/partial-strengthSemi-rigid/full-strength

Semi-rigid/partial-strength

Partial-strengthSemi-rigidSemi-continuous

Rigid/full strengthFull-strengthRigidContinuous

Elastic-plastic analysisRigid-plastic analysis

Elastic analysis

TYPE OF FRAME ANALYSISMODELLING

19


20

Global Analysis of Lattice GirdersHollow sectionsAssumption the members connected by pinned joints (for the distribution of axial forces)

Secondary moments (due to rigidity of joints)Moments resulting from transverse loadsMoments resulting from eccentricities

Not (if criter. is satisfied)JointNoBrace memberNoTension chordYes

YesNot if criter. is satisfied

Compression chordEccentricityTransverse loadingSecondary effects

Source of the bending momentType of component

21

Secondary MomentsMoments, caused by the rotational stiffness's of the joints, may be neglected in the design of members and joints.

Joint geometry is within the rangeRatio of the system length to the depth of the member in the plane is not less than 6

22

Moments Resulting from Transverse LoadsMomets should be taken into account in the design of the members to which they are applied

Brace members may be considered as pin-connected to the chords.

Moments resulting from transverse loads applied to chord members need not be distributed into brace members, and vice versa.

Chords may be considered as continuous beams, with simple supports at panel points.

23

Moments resulting from Eccentricities

Centric

Negative eccentricity

Positive eccentricity

24

Moments resulting from EccentricitiesMay be neglected in the design of tension chord members and brace membersMay be neglected in the design of connections if the eccentricities are within the limits:

−0,55 d0 ≤ e ≤ 0,25 d0

−0,55 h0 ≤ e ≤ 0,25 h0

e eccentricityd0 diameter of the chordh0 depth of the chord, in the plane of the lattice girder

25


26

Based on Resitance

φ

Full strength connection

Partial strength connection Bending moment resistance

MMoment,

Rotation,

of connected beam

M b,pl,Rd

27

Based on Stiffness (Values for Column Bases)Accuracy of calculation

5% Ultimate Limit State20% Serviceability Limit State

0

0,2

0,4

0,6

0,8

0 0,01 0,002 0,003

1,0

Sj.ini.c.s

S j.ini.c.n = 30 E I / L cc

c c = 12 E I / L

Relative moment

36,1o =λ

M j / M pl,Rd

, radPinned column base

Semi-rigid column base

Rigidcolumn base

φ_

= EL M

c

c c,pl,Rd

I φ

φ28

Based on Rotational CapacityDeformation capacity of connected member

M

φ

Elastic rotation

(Class 2)(Class 1)

(Class 3)Brittle connection

Ductile connectionSemi-ductile connection

φ

M M

φM

Moment,

Rotation,

of connected beam

Ultimate rotationof connected beam

29

Column Bases – Braced FramesPrediction of column resistance based on the lower support bending stiffness

01020304050

0 2 4 6 8 10Relative slenderness of column

Simplified boundary

Accurate boundary

S j.iniE I / Lc c

Relative stiffness of base plate

0λ30

Column Bases – Braced FramesPrediction of column resistance based on the lower support bending stiffness

for 5,0≤λ is the limit 0S ini.j > ,

for 93,35,0 << λ is the limit ccini.j L/IE)12(7S −≥ λ ,

and for λ≤93,3 is the limit ccini.j L/I48S ≥ .

The limiting stiffness 12 E Ic / Lc (slenderness lower than 36,1=λ )

31

Classification of JointsNational Annex may give additional information on the classification of joints by their stiffness and strengthin Cl 5.2.2.1(2)Pin is difficult to define

Small moment resistanceSmall stiffnessHigh deformation/rotational capacity

32


33

Modelling of Joint by Rotational SpringsComponent method

Joint Shear panel Shear panel separatelly in connections

φT

MaM b

b

φa

Ma M b

34

Shear Panel

Forces and moments acting on the joint

Forces and moments acting on the web panel at the connections

Mb2,Ed

Nb2,Ed Vb2,Ed Vb1,Ed

Mb1,Ed

Nb1,Ed

35

Distribution of Internal Forces

Shear forcesA bolt row in shear onlyRest of shear resistance of each bolt rowSupplement of shear resistance of each bolt row

Plastic distribution

Ft1.Rd

Fc.Rd

Ft2.Rd

F t3.Rd

≤

=

=

=

Elastic-plastic distribution

F t1.Rd

F c.Rd

F t2.Rd

< F t3.Rd

≤

=

=

Elastic distribution

Ft1.Rd

F c.Rd

< F t2.Rd

< F t3.Rd

=

z3

z2

z1

≤

36


1

Welded Connections



2


3

TopicsBases of designFillet weld

Design modelDesign independent of the direction of loadingVery long welds Design exampleEffective width of welded beam-to-column connectionWeld design for full resistance of connecting members

Welding in cold-formed zonesDesign of partially penetrated butt weldSummary 4

Bases of Design

Fillet weldsBut weldPlug weldsGroove welds

EN 1993-1-8 requirementsDesign rules + Design models

a

5

Fillet welds –Definition of Effective Throat Thickness a

The effective throat thickness of a fillet weld should not be less than 3 mm

Design throat thickness of flare groove welds in rectangular structural hollow section 6


Design modelDesign of independent of the direction of loadingVery long welds Example - Modelling the resistanceEffective width of welded beam-to-column connectionWeld design for full resistance of connecting members

Welding in cold-formed zonesDesign of Partially Penetrated Butt WeldSummary

7

Design Model of Fillet Welds

a effective throat thickness of the fillet weldσ┴ normal stresses perpendicular to the throatσ║ normal stresses parallel to the axis of weld (omitted)τ┴ shear stresses perpendicular to the axis of weldτ║ shear stresses parallel to the axis of weld 8

Plane StressesHuber –Misses- Henckey condition of plasticity (HMH)

Triaxial state of stress (needed exceptionally only)Plane state of stress (needed very often)

σx2 + σz

2 - σx2 σz

2 + 3τ2 ≤ (fy / γM) 2

Uniaxial state of stress (from the material tests)σ ≤ fy / γM0

τ ≤ fy / (γM0 √3)

σx

σz

9

Design Model

( )2II

22 3 τ+τ+σ ⊥⊥ ( )Mwwuf γβ≤

⊥σ Mwuf γ≤

fu Ultimate tensile strength of connected materialβw Correlation factor

γMwpartial safety factor for material of welds10

Correlation factor βw for fillet welds

1,00S 460 NH/NLHS 460 MH/MLHS 460 NH/NLH

S 460 N/NLS 460 M/ML

S 460 Q/QL/QL1

1,00S 420 MH/MLHS 420 N/NLS 420 M/ML

0,90S 355 H

S 355 NH/NLHS 355 MH/MLH

S 355 HS 355 NH/NLH

S 355S 355 N/NLS 355 M/ML

S 355 W

0,85S 275 H

S 275 NH/NLHS 275 MH/MLH

S 275 HS 275 NH/NLH

S 275S 275 N/NLS 275 M/ML

0,80S 235 HS 235 HS 235S 235 W

EN 10219EN 10210EN 10025Correlation factor

βw

Standard and steel grade

11


Design modelDesign independent of the direction of loadingVery long welds Example - Modelling the resistanceEffective width of welded beam-to-column connectionWeld design for full resistance of connecting members

Welding in cold-formed zonesDesign of Partially Penetrated Butt WeldSummary 12

Design Independent of the Direction of Loading

Mww

ud,vw

ffγβ3

=

d,vwRd,w faF =

F w,Rd

V// ,Sd

F w,Sd

L a

N Sd

V⊥,Sd

F w,Rd

⊥

13


Design modelDesign of independent of the direction of loadingVery long welds Design exampleEffective width of welded beam-to-column connectionWeld design for full resistance of connecting members


Very Long WeldsOverloading of weld ends

due to the different deformation of the connected elements

τ ττ τ

Lw

//// // //

15

Long welds

Reduction of design strength( ) 011502021 ,aL,, wLw ≤−=β

00 50 100 150 200 250 300 350 400

βLw

L / a0,20,40,60,81

τ τ

Lw

////

16


Design modelDesign of independent of the direction of loadingVery long welds Design examplesEffective width of welded beam-to-column connectionWeld design for full resistance of connecting members

Welding in cold-formed zonesDesign of Partially Penetrated Butt WeldSummary

17

Two Fillet Welds in Parallel Shear τ la2F=

From plane stress analysis is

( )3fa2F Mwwu γβ≤l

18

0=τΙΙ

2Rσ=τ=σ ⊥⊥

Has to be satisfied

( )Mwwu22 f3 γβ≤τ+σ ⊥⊥

After substitution

( ) ( ) ( )Mwwu2R

2R

2R f2232 γβ≤σ=σ+σ

( )2f MwwuR γβ≤σ

Fillet Weld in Normal Shear

19

Connection of CantileverShear force Sd = FSd.

ha2FSdII =τ

Bending moment Sd = FSd e Transferred by the shape of weld.

Centre of gravity, Iwe and cross section modulus we

For weld at lower flange cross section modulus we,1 and stress is

( ) 1,weSd11 W2M=τ=σ ⊥⊥

For upper weld on flange is

( ) 2,weSd22 W2M=τ=σ ⊥⊥

V

M

WW

Transferred by web

fillets

20

Flange - WebWeld VSd

Vl

Welds are loaded by longitudinal shear force

ISVV Sd=l

where VSd

S Static moment of flange to neutral axisI moment of inertia

This longitudinal force is carried by two welds effective thickness aShear stress

3fa2V MwwuII γβ≤=τ l

Maximum stress is at the point of maximum shear force

shear force

21


Design modelDesign of independent of the direction of loadingVery long welds Worked ExamplesEffective width of welded beam-to-column connectionWeld design for full resistance of connecting members


Effective Width of Welded Beam-to-Column ConnectionConnection to plate deformed out of its plate

23

Effective WidthUnstiffened column flangesIn EN 1993-1-8 Chapter 4.10

twc thickness of column webtfc thickness of column flangetfb thickness of beam flange s equal to fillet radius rc for hot rolled column sections

fcwceff tstb 72 ++=

⎟⎟⎠

⎞⎜⎜⎝

⎛⎟⎟⎠

⎞⎜⎜⎝

⎛++=

yb

yc

fb

fcwceff f

fttstb

2

72

beff

t fb

t fctwc

rc

σ

24

Effective WidthUnstiffened column flangesIn EN1993-1-8 Clause 6.2.4.4

twc is thickness of column webtfc thickness of column flangetfb thickness of beam flange s is equal to fillet radius rc for hot rolled column sections

( )0

72M

ybfbfcwcRd,fc,t

fttkstF

γ++=

⎟⎟⎠

⎞⎜⎜⎝

⎛= 1min ;

tftf

kfbyb

fcyc

25



Throat thickness of a fillet weld used in a hollow section jointsDesign of Partially Penetrated Butt WeldSummary 26

Weld Design for Full Resistance of Connecting Members - Loading by Normal Force

Not directly in code

σ = FSd / (t h)FSd the acting design forcefu plate design strengtht the thinness of connecting plateb width of connecting platefull capacity of a plate the thickness S235:

Mwu /ft,a

γσ70>

t,t,,/

t),/(,/f

t)/f(,a

Mwu

My 50520251360

1012357070 0 ≈==>γγ

σ τ⊥

w

σ ⊥

σ F

tSd

27

τ

τ

h

t

VSd

Weld Design for Full Resistanceof Connecting Members - Loading by Shear Force

τ = VSd / (t h) VSd the design shear force in weld

full capacity of a plate the thickness S235

t,t,,/

t),/(,/f

t)/(f,

/ft,a

Mwu

My

Mww40360

251360311235850

3850850 0 ≅=

∗=≈>

γγ

γτ

28

Weld Designor Full Resistance of Connecting Members

Loading by shear force ∼ 0,5 t

Loading by normal force ∼ 0,4 t

29




Welding in Cold-Formed Zones

May be carried out within a length 5 t either side of a cold-formed zone

Cold-formed zones are normalized after cold-forming but before weldingr / t - ratio satisfy the relevant values:

anyany2412106

≥ 25≥ 10≥ 3,0≥ 2,0≥ 1,5≥ 1,0

Maximum thickness (mm)Fully killed Aluminium-killed steel

(Al ≥ 0,02 %)r / t

31




Butt weldsFully suply the cross-section

For low quality is decreased design strengthCalculation as fillet weld

V

1/2 V

U

π

33

Design of Partially Penetrated Butt Welda = anom – 2 mm

a

cnom

t

anom.2

a nom.1a

a

nom

nom nom

34

Full penetration T joints

Partial penetration with an effective width

.

taa ,nom,nom ≥+ 21

5tcnom ≤

mm3≤nomc

taa ,nom,nom <+ 21

mm2nom,11 −= aamm2nom,22 −= aa

a

cnom

t

anom.2

a nom.1a

a

nom

nom nom

35




SummaryChapter 4 Welded connections

+Rules for connection of open sections

Component methodRules for connection of hollow sections

Welded

1

Bolted Connections(Connections made with bolts, rivets or pins)



2


3

Scope of the LectureGeneral Design resistance of individual fasteners

Non-preloading bolts Single lap jointsBearing through packingSlotted holesLong joints RivetsAnchor bolts

Slip-resistant connections using 8.8 or 10.9 bolts Design for block tearing Lug angles Pin connectionsInjection bolts Summary 4

Material

Nominal values of the yield strength fyband the ultimate tensile strength fub for bolts

Note: Bolts 12.9 are not allowed

1000800600500500400400fub (N/mm2)

900640480400300320240fyb (N/mm2)

10.98.86.85.85.64.84.6Bolt class

5

Categories of Bolted Connections

8.8 or 10.9Ft,Ed ≤ Ft,RdFt,Ed ≤ Bp,Rd

EPreloaded

from 4.6 to 10.9Ft,Ed ≤ Ft,RdFt,Ed ≤ Bp,Rd

DNon-preloaded

Tension connections

8.8 or 10.9Fv,Ed ≤ Fs,RdFv,Ed ≤ Fb,Rd

Fv,Ed ≤ Nnet,Rd

CSlip-resistant at ultimate

8.8 or 10.9Fv,Ed.ser≤ Fs,Rd,serFv,Ed ≤ Fv,RdFv,Ed ≤ Fb,Rd

BSlip-resistant at serviceability

from 4.6 to 10.9Fv,Ed ≤ Fv,RdFv,Ed ≤ Fb,Rd

ABearing type

Shear connections

6

Holes (ENV 1990)Normal

+1 mm for M 12+2 mm for M 16 up M 24+3 mm for M 27 and bigger

Extra large With loose 3 mm (M12) up 8 mm (M27)Slotted (elongated) Accurate – flushed bolts

for bolt M20 must be the clearance Δd < 0,3 mm

7

p 1

p2

e 1

e 2

Positioning of Holes for Bolts and Rivets

Minimum values for spacings

2,4 d0Spacing p2

2,2 d0Spacing p1

1,5 d0Distance in slotted holes e4

1,5 d0Distance in slotted holes e3

1,2 d0Edge distance e2

1,2 d0End distance e1

8

Maximum Values for SpacingsEdge and end distances are unlimited, except :

for compression members in order to avoid local buckling and to prevent corrosion in exposed members and;for exposed tension members to prevent corrosion.

9

Local Buckling of Platein compression between the fasteners:

need not to be checked if p1 / t is smaller than 9 ε

according to EN 1993-1-1 using 0,6 p1 as buckling length

t thickness of the thinner outer connected part

yf/235=ε

10

Staggered Rows

minimum line spacing of p2 = 1,2d0

11




Resistance in Shear in One Shear PlanePlane of shear is going through threads of bolt:

For classes 4.6 a 5.6

( ) M2subRd,v Af6,0F γ=

For classes 8.8 a 10.9

( ) M2subRd,v Af5,0F γ=A s Core area of cross section of bolt

γ M2 Partial safety factor of bolt

f ub Ultimate strength of bolt

13

Resistance in Shear in One Shear PlanePlane of shear is going through shaft of bolt

( ) M2ubRd,v Af6,0F γ=

A Full area of cross section of bolt

γM2 Partial safety factor of bolt

fub Ultimate strength of bolt

14

Resistance in Bearing

p 1e1

d

d

0

Fb.Sdt minimum thickness in one direction

d diameter of boltd0 diameter of holef ub strength of boltf u strength of material

( ) M2uRd.b, tdf5,2F γα=

where α is minimum from formulas

0,1;ff;41d3p;d3e uub0101 -

(0,8 in oversized holes)

15

Resistance in BearingIn oversized holes reduction 0,8

Load on a bolt is not parallel to the edge, the bearing resistance may be verified separately for the bolt load components parallel and normal to the end

e30

L

t

p 1

w pt

1

e1

10

IPE 200

14060

5,6

40

40

445010

V = 110 kNSd

P 10 - 140 x 100M 20 - 5.6

10

R 10 20

16

Bearing of Plate and Bolt

Inner bolt

Outer bolt

17

Bearing Resistance of Bolt Group

For the holes 2:

For the holes 1:

1)Total bearing resistance is based on direct summarising

2)Total bearing resistance is based on smallest of the individual resistances

( ) ( )222

5232520,75240252M

u

M

u

M

uRd,b

ftd,,ftd,,ftd,Fγγγ

α ⋅=⋅⋅+⋅== ∑

( ) ( )222

5261520,40240252M

u

M

u

M

uRd.b

ftd,,ftd,,ftd,Fγγγ

α ⋅=⋅⋅+⋅== ∑

40321

3 0

0

0

1 ,dd,

de

===α

750250125033250

3 0

0

0

1 ,,,dd,

dp

=−=−=−=α

p 1 e 1

F F

Holes 1 Holes 2

p 1 = 3 d 0 e 1 = 1,2 d 0

18

Tensile Resistance

( ) M2sub2Rdt, γAfkF =

A s Area of core of boltγMb Partial safety factorf ub Ultimate bolt strength

k2 = 0,63 for countersunk boltk2 = 0,90 for regular bolt head

19

Punching Shear Resistance

tp plate thickness

dm the mean of the across points and across flats dimensions of the bolt head or the nut, whichever is smaller

Bp,Rd = 0,6 π dm tp fu / γM2

221 dddm

+= 1d

2d

wd dm

20

Combined Shear and Tension

Shank in shear plane

0

0,5

0

Ft,expF t

Experimental tensile resistance / predicted tensile resistance1,0 Treads in shear plane

Fv,expFt

Experimental shear resistance

0,5 1,0

predicted tensile resistance

1F4,1

FFF

t,R

t,S

v,R

v,S ≤+

Owens G.W., Cheal D.B.: Structural Steelwork Connections, Butterworths, 1989.

21

Single Lap Connection with One BoltReduction of bearing resistance

2

51M

uRd,b

tdf,Fγ

≤

30 30

M 16 - 5.6P5 - 60 x 840

58FSd

22



Slip-resistant connections using 8.8 or 10.9 bolts Design for block tearing Lug angles Pin connectionsInjection bolts Summary

23

Shear and Bearing pass through PackingReduction of bolt shear resistance

β

t p

0,5

1,0

0 0,3 d 1,5 d

p

1,0 d

pp 38

9td

d+

=β

01,p ≤β

t p

24

Bearing Resistance in Slotted Holes60% of resistance in circular holes (force perpendicular to the long direction of the slot)

110

25 50 35 10

40 40 8 16

18

8

M 16

110

25 50 35 10

40 40

22 18

M 16

Displacement , mm 0

20

40

60

80

100

120

140

160

0 5 10 15 20 25 30 35 40

Force, F, kN

Slotted holes,

Circular holes, 180

(test 1c-16-1-d+2)

(test 5c-16-1-d+2,5)

8 16 8

45

200

25

Long ConnectionReduction of shear resistance

0

0,2

0,4

0,6

0,8

1

0 15d 65d

β Lt

L j

L j

0,75

ddL j

Lf 20015

1−

−=β

01,Lt ≤β

750,Lt ≥β

26


Non-preloading bolts Single lap jointsBearing through packingSlotted holesLong connections RivetsAnchor bolts


27

Rivet ConnectionsPhilosophy of design was used for bolts (class A)

Bolts spacing's recommendations are coming from rivets

28




29

Anchor BoltsThe nominal yield strength does not exceed

when the anchor bolts act in shear 640 N/mm2

otherwis not more than 900 N/mm2

For bolts with cut threads reduction by a factor of 0,85

30




31

Slip-resistant Connectionsusing 8.8 or 10.9 Bolts

F

Fs.Rd

p.Cd

( ) Cd,pM3,sersRd.s, FnkF γμ=

Fp,Cd is design prestressing force of bolt ub A s),μ friction coefficient

n number of friction planesks coefficient corresponding to clearance of hole

(= 0,7 f

Prestressing force

32

Friction Coefficient μTests

EN 14399-2:2002 High strength structural bolting for preloading -Part 2 : Suitability Test for Preloading

Table for class of friction surfaces With painted surface treatments a loss of pre-load may occur over time.

0,2D cleaned (EN 1090)0,3C cleaned (EN 1090)0,4B blasted (EN 1090)0,5A blasted, metal spraying (EN 1090)

Slip factor µClass of friction surfaces

33

Hole Size Coefficient ks

0,63Long slotted holeswith the axis of the slot parallel to the direction of load transfer

0,76Short slotted holes with the axis of the slot parallel to the direction of load transfer

0,7Long slotted holes with the axis of the slot perpendicular to the direction of load transfer

0,85Oversized holes or short slotted holes with the axis of the slot perpendicular to the direction of load transfer

1,0Normal holes

ksDescription

34

Combined Tension and Shear

2

80

M

Ed,tC,ps )F,F(nk Fs,Rd

γμ −

=

F b F p

F b

F t

δ b

δ b,ext

δ p,ext δ p

Δ

F j

F j Δ

elongation of the bolt

bolt

plate shortening

external

total bolt force

tensile force preload

35




Block TearingBlock tearing consists of failure in shear at the row of bolts along the shear face of the hole group accompanied by tensile rupture along the line of bolt holes on the tension face of the bolt group.

NEd

N Ed

NEd

N Ed

37

Test

Orbison J.G., Wagner M. E., Fritz W.P.: Tension plane behavior in single-row bolted connections subject to block shear, Journal of Constructional Steel Research, 49, 1999, s. 225 – 239. 38

FE Model

Topkaya C.: A finite element parametric study on block shear failureof steel tension members, Journal of Constructional Steel Research, 60 , 2004, s. 1615 – 1635, ISSN 0143-974X.

Rupture

39

Design ModelSymmetric bolt group subject to concentric loading

Veff,1,Rd = fu Ant / γM2 + (1/√3) fy Anv / γM0

Ant net area subjected to tensionAnv net area subjected to shear

Eccentric loadingVeff,2,Rd = 0,5 fu Ant / γM2 + (1/√3) fy Anv / γM0

40

40

3525

8 x M16; 70

P10; 1.4401

L - 100 x 100 10

30 + 7 x 30 +30

70

100

70materiál 1.4401

240

60

35

240

Worked Example - Angle

In plate (staggered rows)

In angle (staggered rows)

=+=M0

nvy

M2

ntuRdeff,1, 3

1γAf

γAfV ( ) ( ) kN48140972

101110921862402220

31

1025110923553050

33 =+=×

××−×−×××+

×××−××

=,,

,

=+=M0

nvpy,

M2

ntpu,Rdeff,2, 3

10,5γAf

γAf

V( ) ( ) kN27420470

1011109183240220

31

10251101896053050

33 =+=×

×−×−××+

××−××

=,,

,

41

Single Lap ConnectionReduction of bearing resistance

2

51M

uRd,b

tdf,Fγ

≤

e2

d

t

( )N

e d t fu Rd

u

M.

, ,=

−2 0 0 52 0

2γ

42

Single Lap Connectionp1

p1 p1

p1

p1 p1

NA f

u Rdnet u

M. =

β

γ2

2

NA f

u Rdnet u

M. =

β

γ3

2

≤ 2,5 d0≥ 5 d0

0,70,53 and more bolts β3

0,70,42 bolts β2

Pitch p1

Reduction factors

43

Worked Example – Fin Plate

45

70

70

45

3 x M20, 8.8

50 50

35

60

10

IPE 300S235

meteriál S235

5

P10 - 230 x 110HEA 200S235

230

= 100 kNV Sd

44

Worked Example – Fin Plate, Shear Resistance

In beam web

80

70

70

5050

45

70

70

45

230

kN19901

517112353

1251

927636050=××+

××=

,,

,,,

M0

nvb1y,

M2

b1u,Rd,11 3

150γγAf

Af,V += nt

45

Worked Example – Fin Plate, Tying Resistance

In beam web

70

70

5050

45

70

70

45

M0

nvb1y,

uM,

ntb1u,u,6Rd, 3

1γγAf

AfN += kN298

018553235

31

116681360

=××+×

=,

,,

,

46




47

Lug Angles

1. The lug angle to transmit a force 1,2 times the force in the outstand of the angle connected.

2. The fasteners connecting the lug angle to the outstand of the angle member should be designed to transmit a force 1,4 times the force in the outstand of the angle member.

3. The connection of a lug angle to a gusset plate or other supporting part should terminate at the end of the member connected.

4. The connection of the lug angle to the member should run from the end of the member to a point beyond the direct connection of the member to the gusset or other supporting part. 48




49

Pin ConnectionsAnalysis

As bolt (shear, bearing)As beam (bending)Combination of shear and bending

FSd

d = 30

t1 = 10

c = 1t2 = 18

d3 = 20

t = 101

c = 1

t1cc

t1 t2

MSd

50

Design of PinGiven thickness t

Given geometry323

22

0000 dft

Fc:

dft

Fa

y

MEd

y

MEd +≥+≥γγ

t,d:f

F,t

y

MEd 5270 00 ≤≥

γ

51

Analysis of Pin - ShearResistance of one shear area of pin in shear

( ) SdSd.vMpupRd.v F5,0FfA6,0F =≥γ=

FSd applied forcef up strength of pinγMp = 1,45 partial safety material factor

A Cross sectional area of pin

52

Analysis of Pin - Bending

t1cc

t1 t2

MSd

Resistance of pin in bending( ) ≥γ= MpypeRd fAW8,0M l ( )( )1SdSd t2c4t8FM ++=

FSd applied force

f yp yield point of pin

γMp = 1,45 partial safety material factorA cross sectional area of pin

W del = π 3 32 cross sectional elastic modulus of pin

53

Analysis of Pin –Combination of Bending and Shear

t1cc

t1 t2

MSd

Stresses due to bending and shear:

( ) ( )M M F FSd Rd v Sd v Rd2 2 1+ ≤, ,

54

Analysis of Pin - Bearing

Bearing stress of plate and pin( ) MpyRd,b fdt5,1F γ= pro yyp ff ≥ a tt2 1 ≥

f y yield point of platesf yp yield point of pin

γMp = 1,45 partial safety material factor

55

Analysis of Pin - ServiceabilityReplaceable pinthe contact bearing stress should satisfy σh,Ed ≤ fh,Rd

fh,Ed = 2,5 fy / γM6,ser

d the diameter of the pin;d0 the diameter of the pin hole;FEd,ser the design value of the force to be transferred in bearing,

under the characteristic load combination for serviceability limit states

td)dd(FE

, ser,EdEdh, 2

05910−

=σ

56




57

Injection Bolts

Bolts of class 8.8 or 10.9The design ultimate shear load of any bolt in a Category APreloaded injection bolts should be used for Category B and C connections

σ

σσσ

σ

σ

1

112

2

2

1

2

2

1

2

t

t

t

t1.0

1,01,33

2.0 /

β

t

58

σ

σσσ

σ

σ

1

112

2

2

1

2

2

1

2

t

t

t

t1.0

1,01,33

2.0 /

β

t

Bearing Strength of an Injection Bolt

ß coefficient depending of the thickness ratiofb,resin bearing strength of the resin tb, resin effective bearing thickness of the resinkt 1,0 for serviceability limit state

1,2 for ultimate limit stateks 1,0 for holes with normal clearances or (1,0 - 0,1 m),

for oversized holes; m the difference (in mm) between the normal and oversized hole dimensions

4M

sinre,bsinre,bstresinRd,b,

ftdkk F

γβ

=

59




SummaryConnections made with bolts, rivets or pins

in Chapter 3 of EN 1993-1-8Non-preloaded boltsPreloaded bolts – preload (0,7 fub)Injection bolts (replacement of rivets;

bolts 8.8 and 10.9)Pins (including serviceability)

1

Basics of structural joints(Structural Joints Connecting Open Sections)



2


3

Scope of the LectureGeneral Component methodBasic componentsAssembly

ResistanceStiffnessRotation capacity

M-N interactionSummary

4

Different ApproachesExperimentationCurve fittingFinite element analysisSimplified analytical models – Component Method

M

φ

Experiment

Function h

t

lb

a

t M 5

53

31

1 )kM(C)kM(C)kM(C ++=φ

5

Design curve

Joint resistance

M j, Rd

Deformation capacity

φj,Cd

Initial stiffness Sj, ini

Elastic

2/3 M j, Rd limit

φ

Experimental curve

Rotation, , mrad

M, moment, kNm

Moment-Rotation CharacteristicRotational stiffnessMoment resistanceRotation capacity

6




7

Procedure

Web panel in shear

Connection

Components in tension

Column web in tension

Column web in compression

Components in compression

Joint

Decomposition of jointComponent descriptionJoint assembly

ClassificationRepresentationModelling in analyses 8

Rotational Capacity

0

M

φ

j.RdM

φ el φ u φ Cd

rotational capacity φ pl

Bending moment, kNm

Rotation, mrad

Bilinear model Experimental curve

Plastic

capacityRotationalof joint

9

Decomposition of Joint

Unstiffened column web in shearUnstiffened column web in compressionBeam flange in compressionColumn flange in bendingBolt row in tensionEnd plate in bendingUnstiffened column web in tension

10

Background ReferencesZoetemeijer P.: Summary of the research on bolted beam-to-column connections, TU-Delft report 26-6-90-2, Delft, 1990.Zoetemeijer P.: Summary of the Research on Bolted Beam-to-Column Connections (period 1978 - 1983), Ref. No. 6-85-M, Steven Laboratory, Delft, 1983. Zoetemeijer P.: Proposal for Standardisation of Extended End Plate Connection based on Test results -Test and Analysis, Ref. No. 6-83-23, Steven Laboratory, Delft, 1983.

11

Practical Applicationof the Component Method

Design tablesGreen bookBlue book

Computer programs

Simplified hand calculation

12

Spring ModelsParallel configuration

Serial configuration

F 1

21

2

d

Fu = F1.u + F2.u k = k1 + k2 δ = min (δ1; δ2)

F 1 21

2

d

Fu = min (F1.u; F2.u) 1 / k = 1 / k1 +1 / k2 δ = δ1 + δ2 .

13




14

Description of Basic Components

The structural properties of basic joint components are described in Chapter 6 of EN 1993-1-8.e.g.

Column web panel in shear Column web in transverse compression Column web in transverse tensionColumn flange in bending End-plate in bending Flange cleat in bending

etc.

VEd

VEd

Fc,Ed

Ft,Ed

Ft,Ed

Ft,Ed

Ft,Ed

15

Bolts in TensionAnalytical model

Stiffness coefficient

Resistance, see boltsDeformation capacity - britle

Ft,Ed

s

bEd,tb AE

LF2

=δ

b

s

b

Ed,tb L

A,EF

k 02==δ

b

sb L

A,kk 6110 ==

16

End-plate in Bending

Ft,Ed

Analytical modelStiffness coefficient

IEmF Ed,t

p 3

3

=δ

3

3

3

3

3 5012233

mtL

,m

tL

mFEIEF

EF

k ini,eff

ini,eff

Ed,t

Ed,t

p

Ed,tp ====

δ

effeff.ini L 1,7 L =

3

3

654 850m

tL,kkkk effp ====

17

End-Plate Resistance

Ft,Ed

By equivalent T-stub in tension

Deformation capacity - ductile

n m

t

F

BB

Leff

2

18

Failure Modes

Mode 1 - Plate failure

Mode 2 - Plate and bolts failure

Mode 3 - Bolts failure

19

Bolt head / washer size influence

Mode 1 only

u

n m

F/2 F/2

Q/2

ϕ

F/4

Q Q

Q/2

F/4

Q/2

F/4

Q/2

F/4

d w d w

C

ϕ

C

un m

F/2 F/2

Q

F/2

Q

F/2

Q Qϕ ϕ

20

Effective LengthCircular failure

Single boltBolt group

Another failureSingle boltBolt group

21

Circular Failure

Virtual workon cone deformation

mL cp,eff π2=

⇒

2 r

F ϕ

r = m

δ

r = n

F

F

F

F

ϕ

x

r

δ

αα

ααα

ϕ r´/2

ϕ/2

ϕ/2

22

Bolt in Corner

m L op,eff α=

In EN 1993-1-8 graph only

emm+

= 22λ

emm+

=1λ

0,90,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

0,0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8

λ 2

λ1

= 8 p2 5,5 4,75 4,45α

23

Bolt at Oversize

bp

Yield lines

e mx

e

mx e

mx

e mx

wWeld

24

T stub Position

25

Column Flange with Backing Plates

Increase of resistance Mode 1only

hbp

ebp

ebp

m

MM F Rd,bpRd,,pl

RdT,1,24 1 +

=

02

1250 Myf,effRdpl,1, /ft,M γlΣ=

02

1250 Mbp,ybp,effRdbp, /ft,M γlΣ=

26

Flange Cleat in BendingAs equivalent T-stub flange

27

Influence of Gapg ≤ 0,4 ta g > 0,4 ta

Effective length ℓeff = 0,5ba

ra memin

0,8 r a

g 0,4 t a≤

ra memin

0,5 t a

g 0,4 t a>

ba

28

Another Componentssee EN 1993-1-8

29




30

Design ResistanceWelded connection

zFM Rd,tRd,j =

zFt,Rd

Fc,Rd

M j,Rd

31

Design ResistanceBoted connection – one bolt row

∑= i iRd,tiRd,j zFM

zz

Ft.Rd

Fc.Rd

Ft.Rd

Fc.Rd

32

Simplified Lever Arm

z zz z z

33

Ft1.Rd F

t1.RdF

t1.Rd

More Bolt Rows - Firs Bolt Row (start from top)

Ft1.Rd

Ft1.Rd F

t1.Rd

End plate in bending

Column web in tensionColumn flange in bending

Resistenceoffirst bolt row

Beam flange in compression


Colum web in shearLimits byshear and compressed part

34

More Bolt Rows – Second Bolt Row

Ft1.Rd

Ft2.Rd

Ft1.Rd

Ft2.Rd

Ft1.Rd

Ft2.Rd

Ft2.Rd Ft2.Rd Ft2.Rd

Ft2.Rd

Ft1.Rd

Ft2.Rd

Ft1.Rd

Ft2.Rd

Column web in tensionColumn flange in bendingColumn web in tension

Resistance of both bobt rows

End plate in bendingColumn web in tensionColumn flange in bending,

Resistance ofsecond bolt row

Beam flange in compression


Colum web in shearLimit By shear and compressed part

35

More Bolt Rows - Third Bot RowTaking into account bolt rows groupsEtc.

Part in compression

Part in tension

Ft1.Rd

Ft2.Rd

Ft3.Rd

Ft1.Rd

Ft2.Rd

Ft3.Rd

Ft2.Rd

Ft3.Rd

Ft2.Rd

Ft3.Rd

Ft2.Rd

Ft3.Rd

Ft3.Rd

Ft1.Rd

Ft2.Rd

Ft3.Rd

Ft1.Rd

Ft2.Rd

Ft3.Rd

Ft1.Rd

Ft2.Rd

Ft3.Rd

36




37

Rotational StiffnessRotatinal stiffness Sj = M / φ

Deformation or a component

Rotation in jointJoint with more springs

EkFi

ii =δ

zi

i

j

∑=

δφ

∑∑∑∑→====

iii

i

i

i

i

j

jini.j

k

zE

k

zE

kEF

zF

z

zFMS 111

222

μδφ

φ

38

Design curve

Joint resistance

M j, Rd

Deformation capacity

φj,Cd

Initial stiffness

Sj,

ini

Elastic

2/3 M j, Rd limit

φRotation, , mrad

M, moment, kNm

Shape by stiffness ratio factor

Shape Stiffness Ratio FactorFrom curve fitting

1≥⎟⎟⎠

⎞⎜⎜⎝

⎛==

ψ

κμRd,j

Sd

j

ini,j

MM

SS

39

More Components

Mj z

δ

φφ1 φ2 φ3

z z1 2 φ

40

Equivalent stiffness

Lever armz

z

1

4

∑∑

=

iii,eff

iii,eff

zk

zkz

2

∑=

i i

eff

k

k 11

z

zkk i

ii,eff

eq

∑=

41




42

Rotation CapacityFor platic global analysesFor basic safety

Ductile componentsPlate in bendingColumn web in shear

Brittle componentsBots, welds

0,0

M

φ

j.RdM

φ el φ u φCd

φCd

43

Upper Limits for MaterialIn the US standard only

δ

F

δCd,2δCd,1

δ

F

δ Cd,2δ Cd,1

Brittle Ductile

Brittle

Ductile

44

In EN 1993-1-8Deem to satisfy criteria

Welded jointsUnstiffnedUnstiffned in tension + Stiffened in compression + No shear influece

Boted jointsPlate failureEnd plate/column flange thickness

bcmin,Cd h/h,0250=φ

yub f/fd,t 360≤

0150,min,CD =φ

45




46

M-N InteractionFor most portal frame connections (pitched rafters)In EN 1993-1-8

Limit 5% of normal force resistance of connected element Linear interaction

Component method

1≤+Rd,j

Sd

Rd,j

Sd

MM

NN

47

Example

MV

N

Sd Sd

Sd

Moment,

Normal force, kN

Linear interactionComponent method

5 % error

kNm

48

Application of EN 1993-1-8 Procedure

N

FF

F1,t

2,t

3,t

j,t,M,Rd

et

N

F

F

2,c

1,c

j,c,M,Rd

et

Moment

Normal force

Linear interaction

Component method

M

j.t.N

N

j,c,M,RdN

j,t,M,Rd

N

j,t,M=0,Rd Linear interactionN

j,c,M=0,Rd

M

j.c.N

1≤+Rd,j

Sd

Rd,j

SdMM

NN

49

Component Method - Resistance

As for base plates

N SdM Sd

F t.Rd

z

zt

zc

Fc.RdActive part

Neutral axis

Centre of the part in tension

Centre of the part in compression

50

Stiffness

NSd

MSd

NSd

MSdz

Ft.Rd

z

zt

zc

Fc.Rd

Fc.t.Rd

zc.t

zc.b

Fc.b.Rd

Bolts and compressed part Two compressed parts

Simplification to two springsBoltsCompressed part – in centre of flage

51

Evaluation on Tests

10 20 Moment,100

200

-200

-100

Normal force, kN

SN 1500

SN 100000

InteractionComponent method

kNm

Test

-10

52

M - φ Diagram Praha Test

0

5

10

15

20

25

30

0 0,01 0,02 0,03 0,04

Moment, kNm

Rotation, rad

Test SN 1500Prediction by component method

Prediction of resistanceby interaction

53

Evaluation on Coimbra Tests

Moment,

Normal force, kN

Interaction

Component method

-400

0

400

800

-50 050

kNmEE1EE2

EE3EE4

EE5

EE6EE7Experiments

54

M - φ Diagram Coimbra Test

0

20

40

60

80

100

120

0 0,01 0,02 0,03 0,04

Moment, kNm

Rotation, rad

Test EE7

Prediction by component method

Prediction of resistanceby interaction

0,060,05

1

Design of Simple Connections (of Open Sections)



2


3

SSEDTA LectureNew and Flexible Approach to Training for Engineers in Construction

Leson 16 Design of Simple JointsDesign of Simple Joints

Access STEEL information tool on internet

4

List of Lessons related to Connection DesignFlow Charts

Simple connections - fin platesSimple connections - end platesColumn splices for both axial load & momentColumn bases (axial load only)

Non-conflicting Complementary InformationDesign model for simple end plate connectionsA: Detailing guidanceB: Shear resistanceC: Tying resistanceDesign model for simple fin plate connectionsA: DetailingB: Shear resistanceC: Tying resistanceDesign model for simple Column splices (non-bearing)Initial sizing for non-bearing splicesDesign model for simple Column bases - axially loaded

Passive examplesBeam to beam fin plate connectionBeam to column end plate connectionColumn splice (non-bearing)Column base, axially loadedColumn splice (bearing)

5

Example – Fin PlateFlow chart

6

7 8

Example – Fin PlateSubject to shear

1. Fin plate2. Supported beam3. Column4. Supporting beam

1 1 13 3

4

2 2 2

9

Example – Fin PlateMode of failure - subject to shear

VRd,12Supporting column web or supporting beam web (punching shear)

VRd,11Beam web in shear (block shear)VRd,10Beam web in shear (net section)VRd,9Beam web in shear (gross section)VRd,8Beam web in bearingVRd,7Fin plate in buckling (LTB)VRd,6Fin plate in bendingVRd,5Fin plate in shear (block shear)VRd,4Fin plate in shear (net section)VRd,3Fin plate in shear (gross section)VRd,2Fin plate in bearingVRd,1Bolts in shear

10

Example – Fin PlateDuctility requirements

not guided by bolt shear failure

11

Example – Fin PlateRotation capacity requirements

1. Given rules in initial design

or2. Limit of hight and calculate required rotation

rthh b1f,bp 22 −−≤

requiredavailable φφ >

2,b

p

1,b 1

1

1

1

2

e

e

h

e

p

p

e e

z

a

gh

e h

gv

b p

600≤b1h600>b1h 60402012010

50401010010

Fin plate edge distancee2 (mm)

Beam edge distance e2,b (mm)

Horizontal gapgh (mm)

Fin plate width bp (mm)

Fin plate thicknesstp (mm)

Depth of supported beam

hb1 (mm)

12

Example – Fin PlateSubject to tying forces

1. Fin plate2. Supported beam3. Column4. Supporting beam

1 11

2 2 2

3 3

4

13

Example – Fin PlateMode of failure – subject to tying

NRd,u,8Supporting column web in bendingNRd,u,7Beam web in tension (net section)NRd,u,6Beam web in tension (block tearing)NRd,u,5Beam web in bearingNRd,u,4Fin plate in tension (net section)NRd,u,3Fin plate in tension (block tearing)NRd,u,2Fin plate in bearingNRd,u,1Bolts in shear

14

SummaryDesign of simple connections not described in EN 1993-1-8

TablesGreen book UKBlue book GermanyECCS TC10 document (in preparation)

Access STEEL materials on internet

15


16

Thank you for your attention

1

Structural Steelwork EurocodesStructural Steelwork Eurocodes

Design of Simple JointsDesign of Simple Joints

2

Simple JointsSimple Joints

Frames are traditionally analysed assuming joints to be either:

– Pinned.

– Rigid.

However few joints meet these ideals.

3

DesignDesign Considerations of JointsConsiderations of Joints

Rigid Joints:– Expensive to fabricate and construct.

Real Pin Joints:– Also expensive

Simple Joints:– Need to be flexible

4

EC 3 RequirementEC 3 Requirement

EC3 states that:– “A nominally pinned connection shall be designed

so that it cannot develop significant moments which might adversely affect members of the structure.”

5

Joint RequirementsJoint Requirements

Joints must:– Transfer actions.– Accept required rotations.

6

Joint PropertiesJoint Properties

Joints have three principal properties:– 1. Strength:

» able to transfer moments & forces.– 2. Stiffness:

» have an appropriate slope on M - Ø curve.– 3.Deformability:

» Have adequate rotation capacity.

7

Stiffness RequirementStiffness Requirement

S j,ini not greater than: 0,5 E Ib / Lb.

where:S j,ini is the initial rotational stiffness of the connection.Ib is the second moment of area of the connected beam.Lb is the length of the connected beam.

8

Strength RequirementStrength Requirement

Depends upon the members connected.

Ensures that joint has only a small resistance compared to the connected members.

Remember that shear and any axial load must be transferred between members.

9

Maximum Moment ResistanceMaximum Moment Resistance

Mpc is fully plastic moment of resistance of column.Mpb is fully plastic moment of resistance of beam.

Figure 1: Maximum moment resistance requirement for simple joints

If Mpb < 2Mpcthen Mj,Rd = 0.25Mpb

If Mpb > 2Mpcthen Mj,Rd = 0.25*2*Mpc

Mpb

Mpc

MpcMpc

Mpc

Mpb

10

Rotation CapacityRotation Capacity

Joint must not fail as a consequence of any large rotations required.

Not sufficient to consider just the detail of the connection in initial state.

11

Effect of Gap ClosureEffect of Gap Closure

φ

Figure 2 : Effect of gap closure

M

Contact between beamflange and column face

M

φ

12

PracticalitiesPracticalities

Many joints currently assumed to operate as simple joints transfer moments in excess of EC3 limits.

Resulting designs function satisfactorily.

Supported by extensive research.

13

Transfer of ForcesTransfer of Forces

Joints likened to links in a chain.

Strength determined by weakest link.

Principal transfers by:– Welding.– Bolting.– Riveting,(occasionally ).

14

Top and seat cleats(major and minor axes

Beam to Column Joints Beam to Column Joints Example 1Example 1

Seat and stability cleats (major and minor axes)

15

Single web cleat (major axis:bolted to beam and column)Welded fin plate: (minor axis:bolted to beam, welded to column.


Double web cleats (minor axis: Welded to beam, bolted to column).Tab plate: (major axis: welded to beam, bolted to column).

16


Shear plate (major axis) Shear plate (major axis)

17

Typical Beam to Beam JointTypical Beam to Beam Joint

Figure 4:Beam to beam

connections

2.1.2 Should any tying forces need to be considered ( as is the case in theU.K.NAD). Then the connection must also be checked for such action whichwill involve consideration of the following potential failure modes, rememberingthat it will often be necessary to combine the axial and the shear forces to obtain a resultant action.

Double notched end plate connection

Supported beam

Single notched angle connection

Supporting beam

18

Simple Web Angle Connection Simple Web Angle Connection

19


Shear force must be transferred to column.

This involves several steps:– Beam into bolts.– Bolts into angle.– Angle into bolts.– Bolts into column flange.

20

Simple Web Angle ConnectionSimple Web Angle Connection

a1

Lv

a3

a2

21


Web of beam into bolts:– Block shear.

Web of beam into bolts:– Bearing.

Shear failure in bolts.Bearing and block shear in angle legs.Shear in bolts to column flange.Bearing in bolts to column flange.

22

Checks Needed for Tying Checks Needed for Tying ForcesForces

Block shear in beam web (amended failure zone).Bearing in bolts to beam web.Shear in bolts.Tensile capacity of web cleats.Tensile capacity of bolts to column face.

23

Other Detailing GuidanceOther Detailing Guidance

Minimum end distance.Minimum edge distance.Maximum end and edge distances.Minimum bolt spacing.Maximum bolt spacing.

24

SummarySummary

The philosophy of simple joints in terms of idealised and real behaviour has been introduced.The concept of joints as an assemblage of components has been put forward.Requirements for strength, stiffness and rotation capacity have been described.Examples of practical details are provided.

1

Column Bases




Scope of the LectureBasis of designComponents

– Base plate in bending and bolt in tension– Base plate and concrete in compression– Anchor bolt in shear

Assembly– Resistance– Stiffness – Pre-design

Classification Worked examplesSummary

Background MaterialsENV 1993-1-1– Annex L (1992)– Annex A2 – Design of Joints (1992, 1999)

COST C1 - Semirigid connections (EU project, finished 1999)

Fixing by Base Plate

Base plate in bending

and anchor bolts in tension


Anchor bolts in shear

Base plate in bending

and concrete in compression

Component Method

Major components

Baseplate in bending Column flange and web Baseplate and concrete Anchor boltin compressionanchor bolts in tensionin compression in shear


– Base plate in bending and bolt in tension– Base plate in bending and concrete in compression– Anchor bolt in shear



Base-plate in bendingand anchor bolts in tension

eff

Column flange

Base plate

F

t

e m

l

Contact of Edge of T stub

nm

F

Q = 0

Θpδ b

δb = Θp n

Q = 0

b3eff

s3

lim.b LtL

Am82,8L ><=

Lbf

L

d

beL b

Lbe ≅ 8 d

Embedded Anchor Bolt

CEB documents for anchor bolts resistance

0

20

40

60

80

100

120

140

160

180

0 0,2 0,4 0,6 0,8 1 1,2 1,4 1,6Deformation, mm

Force, kN

Experiment W13/98Experiment W14/97Prediction

5010

40

40

315 3

65

9595

P10 - 95 x 95

P6 - 40 x 50 5

24 - 355

10

φ

F

B

Rd.3

t.RdB

t.Rd

F

B

Rd.1

B

Q Q

e

n m

Q Q

B t.RdBt.Rd

FRd.2

Mode 3 Mode 1 Mode 2a) b) c)

F

B B

Rd.1*End plate – contact or no contact

Base plate – no contact

0

0,2

0,4

0,6

0,8

1

0 0,5 1 1,5 2 2,5

Mode 1

Mode 2Mode 3

Mode 1*

F B/ Σ t.Rd

4 eff M pl.Rd / Σ Bt.Rdl

ResistanceF

B B

Rd.1*

m´ML2

F Rd.pleff1.Rd =∗

m = 32

W97-020

50

100

150

200

250

300

350

0 2 4 6 8

Force, kN

Deformation, mm

Simplified prediction

Complex calculationm = 67

W97-12

0

50

100

150

200

250

300

350

0 2 4 6 8

Force, kN

Deformation, mm


Experiment

Complex calculation

Stiffness

No prying

kL t

mpeff=

0 425 3

3

,k

ALb

s

b= 2 0,

Prying accured

kL t

mpeff=

0 85 3

3

,k

ALb

s

b= 1 6,

Effective length of T stub

e m

Prying occured( )e25,1m4m21 +−= αl

m22 π=l

( )211,eff ;minL ll=

12,effL l=

No prying( )e25,1m4m21 +−= αl

m42 π=l

( )211,eff ;minL ll=

12,effL l=

bp

mx

ex

e w e

Pryingl 1 = 4.mx+1,25 exl 2 = 2 π mx

l 3 = 0,5 bpl 4 = 0,5 w + 2 mx + 0,625 exl 5 = e + 2 mx + 0,625 exl 6 = e2mx +π

( )6543211,eff ;;;;;minL llllll=

( )54312,eff ;;;minL llll=

l 1 = 4.mx+1,25 exl 2 = 4π mx

l 3 = 0,5 bpl 4 = 0,5 w + 2 mx + 0,625 exl 5 = e + 2 mx + 0,625 exl 6 = e4m2 x +π

( )6543211,eff ;;;;;minL llllll=

( )54312,eff ;;;minL llll=

No prying

Effective Length for Hollow Sections(not in EN 1993-1-8)

m

b

m

b

aac

bc

eaeb

m

mL .eff π=1

2bL 2.eff =

( ) ( )2222

3 8 ccba

ba.eff bbaam

eeee

L −+−+

=

( ) ( ) 2222

2 bacc ee

bbaam +−

−+−=

)L;L;L;L;L(minL 5.eff4.eff3.eff2.eff1.effeff=

2aL 4.eff =mL .eff π=5

(a)





Base plate in bendingand concrete in compression

Flexible base plate3D behaviour – concrete in crushing

c

f j

L

Column flange

Base plate

F

t

c tw

Sd FRd

Concrete 3D Resistance in Crushing(the same as EN 1992-1-1)

Joint coefficient

Effective width

Effective width

babak 11

j =

⎪⎪⎭

⎪⎪⎬

⎫

⎪⎪⎩

⎪⎪⎨

⎧

+

+

=

1

r

1

b5ha

a5a2a

mina aa1 ≥

⎪⎪⎭

⎪⎪⎬

⎫

⎪⎪⎩

⎪⎪⎨

⎧

+

+

=

1

r

1

a5hb

b5b2b

minb bb1 ≥

a

h

a a

bb

b

1

r

1

r

t

jM

y

ff

tc03 γ

=

ydftM 2

61

=′

2

21 cfM j=′

yj ftcf 22

61

21

=

jM

y

ff

tc03 γ

=

ydftM 2

61

=′

2

21 cfM j=′

yj ftcf 22

61

21

=

c c c

cc

M

t c c

Effective width

Elastic resistance ensuring small deformations, to unit length

Bending moment to unit length

Equivalent length of cantilever c

Effective width

Contact Area

Aeq

Ap A

c c

c

c

c

c

Comparison to FE simulation

0,1

Vertical deformation along the block height

foot of the concrete block

top of the concrete block

Vertical deformation at the surface, mm

elastic deformation of the whole block

predicted value

0,10

deformation at the axis

elastic deformation

deformation at the edge

Vertical deformation, mm

0,0

edge axis

}local deformation under plateF

δglob

δedge

δaxis

Stiffness

δ E Ip

xcfl

δα

rr

c r

F aE A

= deformation of elastic hemisphere

δ rc r

FE L a

=0 85,

E275,1LaE

E85,0*5,1LaE

EFk el.eqcel.eqc

c ===δ

a eq.el = t w + 2,5 t 0Mj

ywweq.str f3

f t 2 + t = c 2 + t = a

γ≈

Comparison to Experiments

0

200

400

600

800

1000

1200

1400

1600

1800

0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9Deformation, mm

Force, kN

Concrete and groutConcrete

Experiment

Prediction based on local and global deformation,

Prediction based on local deformation only

Calculated strengthL

F

δ

t t w

Grout

lower nut

packings

β j = 2 / 3

f c.g ≥ 0,2 f ct g ≤ 0,2 min (a ; b)t g ≥ 0,2 min (a ; b)

h

ttg

gt

45o

tg

g45 o tt





Components in Shear Anchor Bolt in Shear

Format as bolts in shear

Fh

δh

0

Fh

δ h

Resistance in bending and shearReduce resistance in tension

Resistance in tension

4.6

Mb

subRd.v

Af375,0Fγ

=

5.6

Mb

subRd.v

Af250,0Fγ

=





Resistance

Plastic design – force equilibriumComplex shape of contact area

∑−= Rd.tjeffRd FfAN

cjeffbRd.tRd rfArFM += ∑ .

MN Rd

r b

F fj

r c

Rd

t.Rd

Aeff

∑

active part

∑-= Rd.tjeffRd FfAN

cjeffbRd.tRd rfArFM += ∑

Interaction diagram



M

NN0Ft.Rd

compression

MM , N2 2

M , N1 1

tension

M=0

N=0





History of LoadingMoment

Rotation

MRd

SdS j.ini

Plastification of one component

Anchor bolts in tension and one flange in compression

Nonlinear part of the curve

Non-proportional loading

Proportional loading

0 Normal force

MomentNon-proportional

Proportional

resistance

e N0

0

Column base

loading

loading

Simplified contact area



T

MNSd

Sd

z z c

z

F Ft c

c c

cc c c

kk

kp

kbc

tk c k c

c

c

φ

⎧

⎨⎪

⎩⎪

⎟⎟⎟⎟

⎠

⎞

⎜⎜⎜⎜

⎝

⎛

+−=

SdSd

t

Rd.c

SdSd

c

Rd.TRd

N/Mz1

zF;

N/Mz1

zFminM

Stiffness

Simplified contact area



c c

cc c c

kk

kp

kbc

tk c k c

c

c

⎧

⎨⎪

⎩⎪

MSd / NSd = konst. xc <NSd / MSd < ∝

∑−=

i

2

SdSd

SdSdj

k1

zEN/M

N/MSμα

tc

ttcc

kkkzkz

+−

=α

( )μ γ= 1 52 7

,,

γ =+

+

1 2

2

rM N

M Nr

M N

Sd Sd

Rd SdSd Sd

//

///



Sensitivity study, base plate thickness

1015

20

2530

Moment, kNm

Rotation, mrad

t =

0

20

40

60

80

100

120

0 5 10 15 20 25 30

tHE 160 B

MRd

M 20 - 10.9400 kN



Sensitivity study, base plate thickness, resistance

0

2 000

1 000

3 000

100 Moment, kNm

Normal force, kN

Base plate thickness, mm

30

40

25

1520

HE 200 B

MNSd

Sd

30

h = 1 000

M 24

1 600420 590

590

420

1 600

pl.Rd

pl.RdN

Mt,

Column resistance


Lever arm is changing by the activation of one bolt rowLever arm is changing by the activation of both bolt rows t

Comparison to experiment



Force, kN

Anchor bolt

E k b

Base plate

Deformation, , mmδConcrete

E k c

E kp

200100

0 0,5

200100

00,5

200100

0 0,5

W7-4.20-propExperiment

Prediction

Moment, kNm

0

20

40

60

80

0 10

t = 20

HE 160 B

h = 500

N M

Rotation, mrad

Force, kN

Force, kN

Components Assembly

Pre-design, stiffness

Lever arm



MSd

z

MSd

z

20tzE

S2

app.ini.j =





Classification

According to stiffness

Accuracy5% in resistance and 10% in serviceability

Simillar to beam-to-column joints0,6

0,7

0,8

0,9

1

0,0001 0,01 1,00 100,0 S_

S

j,ini,pinS

j,ini,stif

β =FFcr,res

cr.pint = 12 mma1 = b1 = 280 mma = b = 500 mmh = 1000 mmM 24 -420S = 7 100 kNm / radt = 40 mm a1 = b1 = 420 mma = b = 500 mmh = 1000 mmM 24 -420S = 74 800 kNm / ra

log

j,ini,stif

j,ini,pin

Non-Sway by Resistance

Asked stiffness for relative slenderness

oλ ≤ 2 pro oλ ≤ 0,5 Sj,ini ≥ 0pro 0,5 < oλ < 3,93 Sj,ini ≥ 7 (2 oλ - 1) E Ic / Lc

pro oλ ≥ 3,93 Sj,ini ≥ 48 E Ic / Lc

36,1oλ12 E Ic / Lc.Sj,ini ≥

≤

Sway Frames for Serviceability115 kN

5 m

4 m

115 kN

HE 200 B

HE 200 B

5 kN y / yP yS

1,0

0

0,2

0,4

0,6

0,8

0,0001 0,01 1 100 log S

j,ini,pinSSj,ini,stif

In relative values

φ0

0,2

0,4

0,6

0,8

0 0,1 0,2 0,3

1,0

S j.ini.c.s

S j.ini.c.n = 30 E I / Lc c

HingeSemi-rigid connection

Rigidconnection

c c = 12 E I / L

Relative moment

Relative rotation,

36,1o =λ





Worked Example – Base plate

r = 160

a = 1600

a = 420 a = 590

b = 590t = 30

HE 200 B

1

r

r

b = 420 b = 16001

MFSd Sd

b

30

h = 1000

M 24e = 50

e = 90p = 240

b

a

e = 60c

Contact area

h =200c

c

c c

c

c t =9w

t =15f

b =200c

r b

rc

c

beff

cct =15f

Worked diagram

0

0,2

0,4

0,6

0,8

0 0,1 0,2 0,3

1,0

S j.ini.c.s

S j.ini.c.n = 30 E I / Lc c

c c = 12 E I / L 36,1o <λ(for )

Mj.Rd / M Ny.pl.Rd

cc L/IEφφ =

Worked Example – Frame (sway)

FSd

FSd

FSd

FSd F

Sd FSd F

SdF

Sd

2

FSd

2

24 m

9 m

1,2 m

HE 340 B

IPE 550

HE 340 B

Load combination

w = 2,64 kN/m1

w = 1,65 kN/m2

w1

w2

F FFF2

F F F FF2

yy y y y

yyyy

F = 23,00 kNy

F = 0,38 kNx

F FF2

F F F FF2

xx x x xx

xx

F FFF2

F F F FF2

yy y y y

yyyy

F = 26,79 kNy

First load combination Second load combination

N

N

N

N

φ

H φ

H φ

Frame imperfections – by equivalent forcesElement imperfections – by stability check

Elastic design – connection stiffness, pre-design

z

z

z

rad/kNm1002425,8

20*700*000210k

tzES2

f

2

cb.ini.j ===−

rad/kNm0003436

20*700*000210k

tzES2

f

2

bb.ini.j ===−

rad/kNm4005020

30*400*000210k

tzES2

f

2

cb.ini.j ===

ComparisonMaximalmoment

in base platekNm

momentin corner

kNm

momentin rafterkNm

Verticaldeformation

of raftermm

Horizontalsway

mm

0 337,85 318,10 113,68 73,70

108,20 290,13 307,62 109,80 27,43

214,09 305,90 274,73 95,54 19,42

00,5

11,5

2

2,53

MaximalMaximal

of corner





SummaryComponent methodGood accuracy

Worked examples– Savings by taking into account of

stiffness (for serviceability only)– Hand calculation unusual

1

Fire Design of Connections



2


3

Scope of the LectureStructural fire designTemperature of connectionsConnectors at elevated temperatureComponent methodStructural integritySummary

4

Structural Fire Design – Procedure of DesignThermal analysesof fire compartment or local fire

(EN 1991-1-1)Transfer of heat into the structure

(EN 199x-1-2)Mechanical loading at fire situation

(EN 1990, EN 1991-1-x)

Mechanical modelling of structure at elevated temperature(EN 199x-1-2)

5

Connections under FireSteel looses with temperature strength and stiffness

Steel structures expand when heated and contract on cooling

Temperature within the connections is lower compare to connecting steel members

6

EN 1993-1-2 Approaches Fire protection is applied to the member and its connections

Rules based to protect as members

Component approach in EN 1993-1-8 together with a method for calculation the behaviour of welds and bolts at elevated temperature

Connection moment, shear and axial capacity can be evaluated at elevated temperature

7


8

Analytical Models of Heat Transfer1. Section factor (Am /V) method simmilar as for members

Am /V surface/volume ratio2. Based on the temperature of the beam lower flange

Concrete slab

h

400 mm0,62

0,88

> 400 mm0,70

0,88

0,88

hh

θ0

θ0

θ0

h h

θ0

0

≤

0,75 0θ

θ

9

Accuracy Demonstration on 7th Large Scale Fire Experiments on Steel Frame

9000 9000 9000 9000 9000

9000

6000

6000

E

1

2

3

4

F D C B A

Fire Compartment for Structural Integrity Fire Test, January 16, 2003 10

Fire Test January 16. 2003

Motivation

Temperatures in elements and connectionsInternal forces in the connectionsBehaviour of the composite slab

11

Fire Compartment

Interier Exterier, Fire load 12

148 thermocouples57 low temperature strain gauges10 high temperature strain gauges37 deformations10 video cameras2 thermo-imaging cameras

Instrumentation

13

Moderate Fire

Maximal temperature 1108 °C in 55 min 14

No Collapse Reached

Deflections over 1000 mm; residual deflections 925 mm

15

Fin Plate Connection before the Experiment

Fire compartment N

E2D2

E1D1

Fin plate connection

16

C454 - 462

D E

Thermocouples at elements and connections, numbered Cijk

N

C486 - 488 C472 - 475

C441 - 449 C483 - 485 C450 - 453

C480 - 482

C463 - 471 C475 - 479

Thermocouples in compartment 300 mm below ceiling, numbered Gijk

G525

G526

G527

G528

G529

G530

G531

G532

G533

G534

G535

G536

2G521

G522

G523

G5241

C441C442C443

C446

West view

120D1/2-E1/2

C444

C445

C447

C448

C449

C450C451C452

West view

120

C453

E1/2-D1/2

DE1/2

North view

C483C484

C485

FIRE COMPARTMENT

Walls

Window

1st bolt row

4th bolt row3rd bolt row2nd bolt row

Instrumentation

17

400,0°C

980,0°C

400

600

800

t = 26 min. θcon,ø = 275 °C

In 26 min of fire is temperatureof the structure under 400°C

600

1000 , °Cθ

00 30 60 90 mint,

Gas temperatureHeating

Time

18

400,0°C

980,0°C

400

600

800

t = t0 + 0 h 28’ Tcon,ø = 330 °C

600

1000 , °Cθ

00 30 60 90 mint,

Time

HeatingGas temperature

t = 28’ θcon,ø = 330 °Ct = 26 min θcon,ø = 275 °C

25

400,0°C

980,0°C

400

600

800

t = t0 + 0 h 42’ Tcon,ø = 645 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 42 min θcon,ø = 645 °C

Buckling of beam lower flange

26

400,0°C

980,0°C

400

600

800

t = t0 + 0 h 44’ Tcon,ø = 660 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 44 min θcon,ø = 660 °C

Buckling of beam lower flange

27

400,0°C

980,0°C

400

600

800

t = t0 + 0 h 46’ Tcon,ø = 685 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 46 min θcon,ø = 685 °C

28

400,0°C

980,0°C

400

600

800

t = t0 + 0 h 48’ Tcon,ø = 710 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 48 min θcon,ø = 710 °C

29

400,0°C

980,0°C

400

600

800

t = t0 + 0 h 50’ Tcon,ø = 730 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 50 min θcon,ø = 730 °C

30

400,0°C

980,0°C

400

600

800

t = t0 + 0 h 52’ Tcon,ø = 775 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 52 min θcon,ø = 775 °C

31

400,0°C

980,0°C

400

600

800

t = t0 + 0 h 54’ Tcon,ø = 810 °C

600

1000 , °Cθ

00 30 60 90 mint,

Gas temperatureCooling

Time

t = 54 min θcon,ø = 810 °C

32

400,0°C

980,0°C

400

600

800

t = t0 + 0 h 56’ Tcon,ø = 835 °C

The maximal temperature of 1088 °C of secondary beam was reachedby its lower flange in 57 min

600

1000 , °Cθ

00 30 60 90 mint,


Time

t = 56 min θcon,ø = 835 °C

33

400,0°C

980,0°C

400

600

800

t = t0 + 0 h 58’ Tcon,ø = 855 °C

600

1000 , °Cθ

00 30 60 90 mint,


Time

t = 58 min θcon,ø = 855 °C

34

400,0°C

980,0°C

400

600

800

t = t0 + 1 h 00’ Tcon,ø = 880 °C

600

1000 , °Cθ

00 30 60 90 mint,


Time

t = 60 min θcon,ø = 880 °C

35

400,0°C

980,0°C

400

600

800

t = t0 + 1 h 02’ Tcon,ø = 900 °C

Maximal temperatureof fin plate connection 908,3°C was reached in 63 min

600

1000 , °Cθ

00 30 60 90 mint,

t = 62 min θcon,ø = 900 °C

36

400,0°C

980,0°C

400

600

800

t = t0 + 1 h 04’ Tcon,ø = 885 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 64 min θcon,ø = 885 °C

43

400,0°C

980,0°C

400

600

800

t = t0 + 1 h 18’ Tcon,ø = 755 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 78 min θcon,ø = 775 °C

44

400,0°C

980,0°C

400

600

800

t = t0 + 1 h 20’ Tcon,ø = 745 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 80 min θcon,ø = 745 °C

45

400,0°C

980,0°C

400

600

800

t = t0 + 1 h 22’ Tcon,ø = 740 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 82 min θcon,ø = 740 °C

46

400,0°C

980,0°C

400

600

800

t = t0 + 1 h 24’ Tcon,ø = 730 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 84 min θcon,ø = 730 °C

47

400,0°C

980,0°C

400

600

800

t = t0 + 1 h 26’ Tcon,ø = 720 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 76 min θcon,ø = 720 °C

48

400,0°C

980,0°C

400

600

800

t = t0 + 1 h 28’ Tcon,ø = 710 °C

600

1000 , °Cθ

00 30 60 90 mint,

t = 78 min θcon,ø = 710 °C

67

Fin plate connection after the fire test

68

Temperature Differences Measured by Thermocouples

Maximal temperature of fin plate by 4th bolt 908 °C in 63 min

E2D2

E1D1

0

200

400

600

800

1000

0 15 30 45 60 75 90 105 120 135 Time, min

Fin plate, by 4th bolt

Measured temperature, °C

Beam, bottom flange

Difference shown

imaging by the thermo

camera

69Measured 908 °C in 63 min.; predicted 878 °C in 53 min

Analytical Prediction Compared to Test

E2D2

E1D1

0

200

400

600

800

1000

0 15 30 45 60 75 90 105 120 135 Time, min

Measured

from gas measured temp.Connection temperature, °C

based on "section factor"

Predicted

based on measured temp.from beam bottom flange

Predicted

70


71

Bolts and Welds Properties at Elevated TemperatureFactors kb,θ; kw,θ are used to describe the strength reduction

00,10,20,30,40,50,60,70,80,9

1

0 200 400 600 800 1000 θ a ,°C

ky,θ

kb,θ

kw,θ

Carbon steel

Bolt

Weld

72

Bolt Resistance at Elevated TemperatureMarked loss of strength between 300 and 700ºCShear resistance of bolts in fire

Bearing resistance of bolts in fire

Tension resistance of a bolts in fire

γΜ partial safety factor for the resistanceγΜ,fi partial safety factor for fire

fi,m

m,bRd,vRd,t,v kFFγγ

θ=

fi,m

m,bRd,bRd,t,b kFFγγ

θ=

fi,m

m,bRd,tRd,t,ten kFFγγ

θ=

73

Filled Weld Resistance at Elevated TemperatureDesign strength per unit length of a fillet weld in a fire

γΜ partial safety factor for the resistanceγΜ,fi partial safety factor for fire

fi,m

m,wRd,wRd,t,w kFFγγ

θ=

74

Butt Weld Resistance at Elevated TemperatureFor full penetration butt weld up to 700ºCas equal to the strength of the weaker part of the joint using the appropriate reduction factors for steel

For temperatures higher than 700ºCthe reduction factors for fillet welds to butt welds

75


76

Component MethodDecomposition of jointComponnet descriptionJoint assembly

φM

z

77

Component MethodDecomposition of jointComponet descriptionJoint assembly

Component

Cº20;i,y;i FkF θ = ;

Cº20;i,E;i KkK θθ = ;

Cº20;i

;E

;y

;i

;i;i k

kKF

δθ

θ

θ

θ ==

Joint

Cº20;i;y;i MkM θθ = ;

Cº20;i;E

;y

;i

;i;i k

kSM

φφθ

θ

θ

θθ == ;

Cº20;i;E

i ;i

2

;i Sk

k1zES θ

θ ==∑

;

Force

Stiffness

Deformation

Moment

Rotation

Stiffness

θ

θ

θ

θ

δ

78

φ , mrad

M, kNm

20 ºC

800ºC

500ºC100ºC

50

0200 10040 60 80

600ºC700ºC

φM

z

Moment

Rotation

Component MethodDecomposition of jointComponnet descriptionJoint assembly

79

Worked ExampleFire resistance of an end plate connection of the truss lower flangeRequired R30

4 x M24

P 28

85 125 40 45

150500 kN 500 kN

80

Fire ResistanceUnprotectedSection factorFire resistance(exposed to nominal standard fire curve)

ProtectedIntumescent paintFire resistance(exposed to nominal standard fire curve)

4 x M24

P 28

85 125 40 45

150500 kN 500 kN

1m m18,4324,1/0,54V/A -==

t = 44 min

dp = 15 mm

13

p

pm KWm288015,0

1,018,43dV

A --==λ

= 112 mint

81


82

Structural IntegrityIf used catenary actions of beams and slabs

In case of advanced design models

Resistance of connections to horizontal forces at ultimate limit state(for fu)

83

FE Simulation of Cardington Test

Heating Cooling 720°C

I. Beam onlyII. One sectionIII. Full floor

Normal force, kN

Time, min

Model of structure

60 80

300

200

100

0

-100

-200

- 300

20 100

40

4 x 6,0 m

Observed joint 6 x 3,75 m

I. II. III.

84

Experiment in Cardington

853rd floor

99 97 107 105103 101 111 109

83 81 91 89

87 85 95 93

115 113119 117

127 125

123 121

500

500

500

500

113,117115, 119

99, 103 97, 101

83,87 81, 85

127, 123 121, 125

107, 111 105, 109

91, 95 89, 93

4th floor

5th floor

N

of the fire compartment

PLAN Internal wall

7,0 m

11,0 m

E1D1

D1 E1

y

z

309,2

13,821,7

15,2

UC 305 x 305 x 137

320,5

20 20

2020

(339,9)

(314,5)

(19,1)(31,4)

(UC 305 x 305 x 198)

UC 305 x 305 x 137UC 305 x 305 x 198

Window 1,27 x 8,70 m

Low Temperature Strain Gauges

At externalcolumns

86

Protected Columns

Internal External (with 1 m of beam)

87

Measured Stresses at External Columns

Section 500 mm above the floor at 4th floor

83 81 91 89

87 85 95 93

Column D1 Column E1

4th floor

-200

-150

-100

-50

0

50

100

150

15 30 45 60 75 90 105 120 135 150 165 180 195 210

Time, min.

Stress, MPa

8183

87

8991

93

95

D1, E1

500 mm

88

Measured Bending Moments in Columns

Time, min.

Bending moments, kNm

-200

0

200

400

600

0 60 120

a-D1

b-D1c-D1

c-E1

d-E1d-D1

4th floor

D1D2

5th floor

3rd floor

2nd floor

a-D1

b-D1c-D1; c-E1d-D1; d-E1

89

Measured Forces in External Columns

Forces at 3rd, 4th and 5th floor calculated from strainganges at level c,d

(5th foor)3rd floor

4th floor

-500

-400

-300

-200

-100

0

100

200

300

0 60 120

Everage

Everage

d-D1d-E1

c-E1

c-E1

c-D1

c-D1

d-D1 d-E1

Time, min.

4th floor

D1D2

5th floor

3rd floor

2nd floor

Ft,5

Ft,4

Ft,5

Ft,4

Ft,3 Ft,3

a-D1

b-D1c-D1; c-E1d-D1; d-E1

Force, kN

Beam model

90

Required Tie Forces - ReferencesBS 5950: Structural use of steelwork in buildingsEN 1991-1-7 Actions – Exceptional loading

Column ties

Edge ties Beams not used as ties

Tie anchoring

Tie anchoring free column A

re-entrant corner

A

91

Column ties

Edge ties Beams not used as ties

Tie anchoring

Tie anchoring free column A

re-entrant corner

A

Required Tie Forces

gk the characteristic value of permanent action,qk the characteristic value of variable action,L the beam span

st the mean transverse spacing of the ties adjacent to that being checked

[ ]75614150min ;Ls)q,g,(,F tkkt +=

92


93

SummaryWell designed connections at ambient temperature do not need to be recalculated at elevated temperature, if are not directly exposed to fireThe structural fire design according to EN 1993-1-2 is ready for design of connections exposed to fire

Thermal analyses Transfer of heat

EN 1991-1-2

Mechanical behaviour into structureof fire compartment at elevated temperature

EN 199x-1-2

or local fire

94


95

Thank you for your attention

1

Seismic Design of Connections



2


3

Scope of the LecturePrinciplesDesign criteria

Beam-to-column typologiesDesign and fabrication recommendationsWelding technology

Strain-rate loadingM - φ modellingColumn web panelSummary

4

PrinciplesBasic conditions

Over-strength demandDuctility demand (rotation capacity)Robustness demand (reliable detailing together with material behaviour)

Northridge and Kobe earthquakeUnexpected damages to connections

Detailing practicesWelding

5




6

Design Criteria for Seismic Resistant FramesStrong Column/Weak Beam design principlePanel zone strengthConnection strength and degradation characteristicsP-δ effectsMember local buckling

7

Design Criteria in USAGuidelines designs for frames with different anticipated seismic demands

1997 NEHRP ProvisionsAISC Seismic Provisions

Ordinary Moment Resisting Frames (OMRF) Plastic rotation capacities of 0,01 rad

Intermediate Moment Resisting Frames (IMRF)Plastic rotation capacities of 0,02 rad

Special Moment Resisting Frames (SMRF)Plastic rotation capacities of 0,03 rad

8

Requirements for ConnectionSuccessful Performance

Welded JointsThrough-Thickness StrengthBase Material Notch-ToughnessWeld Wire Notch-ToughnessWeld backing and Run out TabsReinforcing Fillet WeldsCope Hole Size, Shape, Workmanship

Bolted JointsBolt Sizing, Hole Type, TighteningNet Section Strength

9

Design Criteria in EuropeEN 1998-1-1 basic provisions concerning steel joints

General rules for steel connections in dissipative structuresRequirements for MRF (Moment Resistant Frame) beam-to-column connections

EN 1993-1-8Rotational stiffness of a joint Sj

axial force NSd in the connected member not exceed 10%Rotation capacity

10




11

Beam-to-Column TypologiesFEMA/SAC test programmes

Connection type classified for certain ranges of Member sizePlastic rotation angle

Connection typesWelded Unreinforced Flange (WURF)Welded Cover Plated Flange (WCPF)Welded Flange Plates (WFP)Welded Vertical Ribbed Flange (WVRF)Welded Column Tree with Bolted Beam (WCT/BB)Welded Single Haunch (WSH)Welded Double Haunch (WDH) 12

Connection TypesPrescriptive Moment Frame Connection

13

Welded Flange Plate Connection

14

Welded Column Tree with Bolted Beam

15

Field Bolted Types of ConnectionsGuidelines as pre-qualified for certain conditions of use

Bolted end plate (BEP)Welded flange plates with bolted beam (WFPBB)Bolted single haunch (BSH)Bolted double haunch (BDH)

16

Field Bolted Types of ConnectionsBolted end plate (BEP)

17

Field Bolted Types of ConnectionsWelded flange plates with bolted beam (WFPBB)

18

Field Bolted Types of ConnectionsBolted double haunch (BDH)

19

Beam-to-Column TypologiesSpecific joints in Japan

Stiffener Stiffener

20

Beam-to-Column TypologiesSpecific joints in Europe

Extended end plate joint

.

.

10M20 - 10.9

.

A

A-A

A

21


Welded joint

.

.

.

B-B

BB

22


Welded flange plate joint

3M20 - 6.6

.

.

.

C-C

CC

23




24

General Rulesfor Steel Connections in Dissipative Structures

Localisation of plastic strains, high residual stresses,and fabrication defects

By experimental evidence

Non dissipative connections of dissipative members Full penetration butt welds

Deemed to satisfy the overstrength criterion

For fillet weld or bolted non dissipative connections

fyd R35,1R ≥

25

General Rulesfor Steel Connections in Dissipative Structures

Bolted jointsIn shear categories B and C (slip resistant) onlyUn tension category E With controlled tightening of the bolts

Shear joints with fitted bolts are also allowed.

Bolted shear connectionThe shear resistance of the bolts should be higher than 1,2 timesthe bearing resistance

The strength and ductility of members and their connections under cyclic loading

Should be supported by experimental evidenceFor all types of connections in dissipative zonesAvailable plastic rotation )L5,0/(p δφ =

26

Requirements for Moment Resistant Frame beam-to-column connections

Structure dissipate energy in the beamsConnections between the beams and the columns should be designed for the required degree of overstrengthMoment resistance Mpl.Rd and the shear force (VG, Ed + VM,Ed) evaluated in 6.6.2 of standard EN 1998-1

Dissipative semi-rigid and/or partial strength connections are permitted provided all of the following conditions

Connections have a rotation capacity consistent with global deformationsMembers framing into the connections are demonstrated to be stable at the ultimate limit state (ULS) Effect of connections deformation on global drift is taken into account

27

Requirements for Moment Resistant Frame Beam-to-Column Connections

Connection design Plastic rotation capacity φCd in the plastic hingeNot less than 35 mrad for structures of ductility class H and 25 mrad for structures of ductility class M with q>2. Under cyclic loading without degradation of strength and stiffness greater than 20%Supported by experimental evidence

Partial strength connections Column capacity design from the plastic capacity of connections

28

Design and Fabrication RecommendationsMaterial propertiesYield-to-Ultimate Stress Ratio (YUSR)

YUSR (fy/fu) = 0,65 or 0,80 For a plastic rotation capacity up to 0,030 rad.

YUSR = 0,95 Reduced plastic hinge length at a plastic rotation capacity of 0,030 rad

The plastified length of the beam with YUSR = 0,95Half the corresponding length in YUSR = 0,80

29




30

Design and Fabrication RecommendationsAccess Hole Size and Geometry

31

Design and Fabrication RecommendationsAccess Hole Size and GeometryIncreasing the size of the web cope

Easier welding on the beam bottom flangeBetter weld quality

Standard ModifiedConfigurations of weld access hole

20

25 10

25

38

2510

25 50

20

32




33

Strain-Rate LoadingThe strain-rate loading has an important influence on the behaviour of jointsA strain rate typical for steel members yielding under seismic action in the range of 0,03-0,06 s-1

Increases the yield strengthLower ultimate strength of welded connectionsDuctility is reduced by up to 27%Decrease of ductility due to high strain rates is not straightforward for cyclic loading

34

Strain-Rate of Carbon Steel

Stress

Strain

Very high speedE Conventional speed

35

Strain-Rate of Carbon Steel

ydyn,yfy,DIF f/f=α

udyn.ufu,DIF f/f=α

Time to yield stress αDIF.fy α DIF.fu

> 1 s 1,0 1,00 100 ms 1,1 1,05 10 ms 1,6 1,05 1 ms 1,9 1,05

36

Strain-Rate of Austenitic Steel

EN 10088-2 1.4307 (304L) increase of f02 o cca 7% - 28%

Stress, MPa800

600

400

200

0

15 30

Strain, % 45 75 60

-1-4

50 s140 s

10 s-1-210 s

-1502 s

-1

-1

37




38

M - φ ModellingStable behaviourUnstable curveSlip in connection

M

φ

M

φ

M

φ

39

M - φ ModellingStable behaviourUnstable curveSlip in connection

40

ParametresRotational capacity

Energy

Rotational capacity and energy

Stiffness

Resistance ini.j

i.ji.M M

M=β

ini.j

i.ji.S S

S=β

( )elixel.jel

iii.E M

Eφφφ

φβ−

=

el.j

i.ji. φ

φβ =Δ

( )eliel.j

ie M

Eφφ

β−

=

41

ModelsCurve fitting

Initial stiffnessMoment resistanceUnloading

ComponentComponent cycling descriptionAssembling

42

Exponential CurveInitial stiffness Sj,ini

Moment resistance M0

Unloading Sj,s

M

φ

SS

S

S

j.ini

j.ini

j.s

j.s

M

φa

0

Ma

- M0

( )( )

( )( )( )φφ

φφ

φφφ −−

⎥⎥⎦

⎤

⎢⎢⎣

⎡ −−+

−−−== − as.jn/1

0

nas.jini.j

as.jini.j1iii.jj S

M2SS

1

SSMSM

43




44

Column Web PanelT joints or double T joints with unsymmetrical loads strong influence on the behaviour of the jointThe resistance of the joint is reduced by between 20 - 40% and the ductility is increased by 150 - 200%, due to the web panel. Adding supplementary web plates on the column web panelcan increase the resistance of the joint.

45

Column Web Panel

For static loads For seismic loads

beff

Ls

beff

r

46

High Strength Bolts in Seismic JointsHigh strength bolts (in US HSFG, High Strength Friction Grip bolts) can be used as ordinary bolts in seismic jointsIt is recommended that they are tightened at a level of 50% of their preloading force. In this case the surfaces of the plates do not have to be prepared for working as a slip-resistant connection

47




48
