SC SOSO STRUCTURAL RESPONSE OF K AND T TUBULAR JOINTS … · 20/05/2010 1 SC SOSO International Workshop on Connect ions in Steel Structures: 2008 Chicago, Illinois, USA June 22-25

20/05/2010

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S C S O S OS C S O S O

International Workshop on Connections in Steel Structures: 2008Chicago, Illinois, USA

June 22-25 2008

STRUCTURAL RESPONSE OF K AND T STRUCTURAL RESPONSE OF K AND T TUBULAR JOINTS UNDER STATIC TUBULAR JOINTS UNDER STATIC

LOADINGLOADINGAuthors:

Luciano Rodrigues Ornelas de Lima [1]

Pedro Colmar Gonçalves da Silva Vellasco [1]Pedro Colmar Gonçalves da Silva Vellasco [1]

José Guilherme Santos da Silva [2]

Luis Filipe da Costa Neves [3]

Mateus Cunha Bittencourt [4]

[1] Structural Engineering Department - UERJ – Rio de Janeiro, Brasil[2] Mechanical Engineering Department - UERJ – Rio de Janeiro, Brasil[3] Civil Engineering Depratment - FCTUC – Coimbra, Portugal[4] MSc Student - PGECIV – Post Graduate Program in Civil Engineering - UERJ – Rio de Janeiro, Brasil

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June 22-24, 2008 Chicago, USA

Summary

Introduction

Why study structural tubular joints in Brazil?

Eurocode 3 Provisions

Numerical Model

Results Analysis and Discussion

FCTUC - Portugal

Results Analysis and Discussion

Parametrical Analysis

Final Remarks

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3


Introduction The intensive worldwide use tubular structural

elements

FCTUC - Portugal Footbridge – Pediatric Hospital – Coimbra - Portugal

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elements

FCTUC - Portugal Footbridge – Vila Nova de Gaia - Portugal

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5



elements

FCTUC - Portugal Footbridge – Rio de Janeiro - Brazil

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Introduction Aesthetical and structural advantages led

designers to be focused on the technologic and design issues related to these structures

Design methods accuracy is a fundamental aspect under the economical and safety points of view

I B il i iti ll t b l t

FCTUC - Portugal

In Brazil initially, tubular space trusses

After 2000 V&M other structural types

Design codes are required EC3

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Introduction Connection design performed since their

behaviour frequently governs the overall structural response

Wardenier et al. (1991)

top chord CHS219.1x7.1338kN

878kN

3

FCTUC - Portugal

diagonal 2 CHS139.7x4.5

432kN

259kN

2 4

Joint design: 382.5kN NO OK!

diagonal 4 CHS88.9x3.6

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Introduction Solve the problem two possibilities change the top chord thickness;g p

use eccentricity in the joint introduction of bending in the joint but, more economical

FCTUC - PortugalJoint design: 657.6kN OK!

432kN

259kN

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Introduction Design rules HSS joints plastic analysis or

on deformation limit criteria

Plastic analysis joint ultimate limit state plastic mechanism corresponding to the assumed yield line pattern

Each plastic mechanism is associated to an i lti t l d it bl f thi

FCTUC - Portugal

unique ultimate load suitable for this particular failure mechanism

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Introduction Deformation limits criteria ultimate limit state

of the chord face to a maximum out of plane deformation of this component

Justification for a deformation versus plastic criterion slender chord faces the joint stiffness is not exhausted after complete onset of yielding and can assume quite large values

FCTUC - Portugal

of yielding, and can assume quite large values due to membrane effects

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Introduction Deformation limit proposed by Lu et al. [7]

“T” JointsUltimate strength (Nu) u = 0.03b

800

1000

1200

1400

d (

kN

)

FCTUC - Portugal

0

200

400

600

0 5 10 15 20 25 30 35

Displacement (mm)

Lo

ad

T1 - Lie et al. (2006)Solid w eld

Without w eldShell w eld

EC3Deformation limit

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Introduction Deformation limit proposed by Lu et al. [7] and

reported by Choo et al. [8] “K” JointsUltimate strength (Nu) u = 0.03dServiceability strength (Ns) s = 0.01d0

Se Nu/Ns>1.5 u and Nu/Ns>1.5 s

2000

FCTUC - Portugal

0

400

800

1200

1600

0 5 10 15 20 25 30

Axial displacement (mm)

Lo

ad (

kN)

1 - right diagonal (compression)

2 - left diagonal (tension)

EC3 ultimate load

Lu et al - ultimate strength

Lu et al - serviciability strength

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Eurocode 3 Provisions Geometrical properties “T” Joints

FCTUC - Portugal

85.0bb

25.00

1 0

0

t2b

35tb

100

0 35tb

101

1

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Eurocode 3 Provisions Geometrical properties “K” Joints

FCTUC - Portugal

0

21

d2dd

25t2

d

0

0 0.1dd

2.00

i 50td

100

0 50td

10i

i

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Eurocode 3 Provisions Failure modes

plastic failure of the chord face

chord side wall failure chord shear failure

FCTUC - Portugal

punching shear failure of a chord wall

brace failure with reduced effective width

local buckling failure of a member

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Eurocode 3 Provisions Chord face plastic load investigated “T” joint

14

sen2

sen1

tfkN

11

200yn

Rd,1

FCTUC - Portugal

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Eurocode 3 Provisions Chord face plastic load investigated “K” joint

with/dd

2.108.1sen

tfkkN 5M

0

1

1

200ypg

Rd,1

Rd,1

2

1Rd,2 N

sinsin

N

FCTUC - Portugal

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Numerical Model Tubular joints shell elements mid-

surfaces of the joint member walls

Welds three-dimensional solid or shell elements (Lee [11] and Van der Vegte [13] )

1000

1200

1400

FCTUC - Portugal

0

200

400

600

800

0 5 10 15 20 25 30 35

Displacement (mm)

Lo

ad

(k

N)

T1 - Lie et al. [10]T1RA4Nx2MATWELDSOLID

T1RA4Nx2MATWELDOUTT1RA4Nx2MATWELDSHELL


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Numerical Model T joints SHELL 181 four-node thick shell

elements bending, shear and membrane deformations Ansys 10.0

Material (three-linear x relationship) and Geometrical Non-linearity (Updated Lagrangian Formulation)

FCTUC - Portugal

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Numerical Model Considered T Joint Lie at al. [12]

Bottom chord

Brace SHS200x16mm

= 90º

FCTUC - Portugal

85.057.0bb

25.00

1

67.11t2

b

0

0 355.12t/b10 00

353.23t/b10 11

SHS350x15mm

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Results Analysis and Discussion T joints Model Calibration performed on

SHS T-joints tested by Lie et al. (2006)

800

1000

1200

1400

ad

(k

N)

N1,Rd = 770kN

N1,Rd = 751kN

ANSYS

EC3

FCTUC - Portugal

0

200

400

600

0 5 10 15 20 25 30 35

Displacement (mm)

Lo

a




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Results Analysis and Discussion Von Mises Stress (in MPa)

0

200

400

600

800

1000

1200

1400

0 5 10 15 20 25 30 35

Lo

ad

(k

N)




FCTUC - Portugal

0 5 10 15 20 25 30 35

Displacement (mm)

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0

200

400

600

800

1000

1200

1400

0 5 10 15 20 25 30 35

Lo

ad

(k

N)




FCTUC - Portugal

0 5 10 15 20 25 30 35

Displacement (mm)

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Numerical Model K joints also used SHELL181 (Ansys 10.0)

Material (bi-linear x relationship – strain Material (bi linear x relationship strain hardening) and Geometrical Non-linearity (Updated Lagrangean Formulation)

FCTUC - Portugal

Best identification of yielded points in

the joint

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Numerical Model Considered K Joint

Bottom chord CHS406x11.28mm

Diagonal CHS162.4x11.28mm

= 30º

FCTUC - Portugal

40.0dd

0

1

25 18t2

d

0

0 0.14.0d/d2.0 0i

5018t/d10 00

504.14t/d10 ii

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Numerical Model Boundary conditions according to Lee

(1999) T C

Model Calibration performed comparingwith EC3 formulation

TNULL

2000

Ns = 1550kN Nu = 1650kN

FCTUC - Portugal

0

400

800

1200

1600

0 5 10 15 20 25 30


Lo

ad

(k

N)

1 - right diagonal(compression)2 - left diagonal (tension)

EC3 ultimate load


N1,Rd = 946kNEC3

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27



400

800

1200

1600

2000

Lo

ad (

kN)



EC3 ultimate load



FCTUC - Portugal

0

0 5 10 15 20 25 30


28



400

800

1200

1600

2000

Lo

ad (

kN)



EC3 ultimate load



FCTUC - Portugal

0

0 5 10 15 20 25 30


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29



400

800

1200

1600

2000

Lo

ad (

kN)



EC3 ultimate load



FCTUC - Portugal

0

0 5 10 15 20 25 30


Scale factor = 2

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Parametrical Analysis T Joint

Braces:

SHS90x16mm (=0 25)

Same bottom chord

SHS90x16mm (=0.25) SHS180x16mm (=0.50) SHS260x16mm (=0.75) SHS280x16mm (=0.80) SHS300x16mm (=0.857)

FCTUC - Portugal

SHS350x15mm

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EC3 (kN) Ansys (kN) – 3%b01600

2000 T Joint

0.25 456.8 400.0

0.50 672.3 668.0

0.57 751.0 770.0

0.75 1169.4 1168.0

0.80 1450.0 1302.0

0.86 1932.0 1440.00

400

800

1200

1600

0 5 10 15 20 25 30 35 40Displacement (mm)

Lo

ad

(k

N)

b1 = 90 (beta = 0.25)

b1 = 180 (beta = 0.50)

b1 = 260 (beta = 0.75)

b1 = 280 (beta = 0.80)

b1 = 300 (beta = 0.857)

Deformation Limit (3%b0)

FCTUC - Portugal

Displacement (mm)

As expected, increasing the value of leads to a strong increase in the strength of the connection specially if ≤ 0.75. However, if ≥ 0.75, an increase of this parameter leads to an increase of strength with a magnitude much smaller than expected. This is due to the fact that for large values of the limit state related to bending does not control, while shear and punching shear begins to be the governing limit states.

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Parametrical Analysis K Joint

Diagonals:Diagonals:

CHS125x11.28mm (=27) CHS162x11.28mm (=40)

CHS205x11.28mm (=31.2) CHS245x11.28mm (=36)

= 30º

FCTUC - Portugal

Same bottom chord CHS406x11.28mm

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3000

K Joint

EC3 (kN)Ansys (kN)

1%d0 3%d0

0.31 795 1316 1419

0.40 946 1600 1820

0.50 1118 2010 2306

0.60 1280 2341 2537500

1000

1500

2000

2500

Lo

ad (

kN)

d1 = 125 (beta = 0.31)

d1 = 162 (beta = 0.40)

d1 = 205 (beta = 0.50)

d1 = 245 (beta = 0.60)



FCTUC - Portugal

As expected, increasing the value of leads to a substantial increase in the connection load carrying capacity. It may be observed that the joint resistance evaluated according to Eurocode 3 (2003) provisions represents a lower limit for the analysed joints.

0

0 5 10 15 20 25 30 35

Displacement (mm)


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Final Remarks FEM T and K tubular joints four-node thick

shell elements bending, shear and membraned f tideformations

Deformation limits criteria were used to obtain thejoint ultimate load

The analysis results assess the EN 1993-1-8 [4]performance

FCTUC - Portugal

maximum load

global load versus displacement curves fully jointstructural response stiffness and ductility capacity

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Final Remarks Observing analytical curves numerical results

achieved a good agreement with the Eurocode 3 [4]i i f th K j i t i t bi d ithprevisions for the K joint resistance combined with a

deformation limit criterion for the deformation of thejoint chord face

For T joints with elevated values differencebetween numerical and EC3 results

A k l d t CAPES/GRICES CNP UERJ

FCTUC - Portugal

Acknowledgements: CAPES/GRICES, CNPq, UERJand FAPERJ financial support provided to enablethe development of this research program

Documents

SC SOSO STRUCTURAL RESPONSE OF K AND T TUBULAR JOINTS … · 20/05/2010 1 SC SOSO International Workshop on Connect ions in Steel Structures: 2008 Chicago, Illinois, USA June 22-25