Numerical Modeling of Duplex Stainless

Steel Structures

Priscila das N. Pereira

William M. Pereira

Isabella Pinheiro Gueiros

Luciano Rodrigues Ornelas de Lima

Pedro Colmar Gonçalves da Silva Vellasco

José Guilherme Santos da Silva

Structural Engin. Department - UERJ – Rio de Janeiro, Brasil

August 31 to September 2011

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Summary

Introduction

Objectives & Methodology

Design Codes Recommendations

Numerical Model

Parametric Analysis

Results Analysis & Discussion

Concluding Remarks

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Introduction

Stainless steel various types of

constructions high corrosion resistance,

durability, fire resistance, ease of maintenance,

appearance and aesthetics

Cost reduction less need for structure

maintenance & increase in its capacity to

dissipate impact loads stainless steel

structure reliability

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Introduction

Arco de Malizia, Italy

Piove di Sacco, Italy

Stainless steel structures examples

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Objectives / Methodology

Development of a numerical model based on FEM

Evaluate LTB Beams Behaviour

RHS Tubular Joint Resistance

imperfection introduction

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Design Rules

Duplex Stainless Steel Beams Eurocode 3

Particular case non-symmetrical patterns different

bending moment diagrams

ULS LTB based on Mcr

• kz rotation end conditions

• kw warping end conditions

• zg relation between load application point and shear centre

• zj degree of assymmetry of the cross section

g2

2

g2

Z

2

T

2

z

Z

W

2

W

z

2

z

Z

2

1cr zCzC

IE

IG)Lk(

I

C

k

k

)Lk(

IECM

Geometrical characteristics updated for

Castellar beam properties

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Design Rules

RHS Tubular Joints Eurocode 3, CIDECT & Feng

& Young Formulation

Eurocode 3

CIDECT

Feng & Young

5M

11

2

00yn

Rd,1 /1.4sen

.2

sen.1

t.f.kN

i

2

00y

fu

*

1sen

t.f.Q.QN

1

4

sen.1

.2Q

i

u 1C

f n1Q

1,1.N.N 1Anp1 0

0A

t100

b1

5M

11

2

00yn

1 /1.4sen

.2

sen.1

t.f.kN

ULS

- c

hord

face

failu

re

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Design Rules

Deformation limit proposed by Lu et al. T Joints

Serviceability limit (Ns) Ds = 0.01d0

Ultimate strength (Nu) Du = 0.03d0

If Nu/Ns ≤ 1.5 Nu

If Nu/Ns > 1.5 Ns

P

D 1%d0 3%d0

Ns

Nu

D

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Numerical Models

Beams shell elements SHELL181

beam member plates mid-surfaces

Material multi-linear s x e

Geometrical Non-linearity (Updated Lagrangian) (Identification of yielded points)

imperfection introduction

eigenvalue analysis

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Numerical Models

Imperfection Considerations

Load step 1

Eigenvector for 1st buckling

mode

Application of imperfection

factor based on EC3 limits

Load step 2

Nonlinear analysis

material and geometrical

nonlinearities 0

10

20

30

40

50

60

70

0 5 10 15 20 25

app

lied

be

nd

ing

mo

me

nt

[kN

]

vertical displcament [mm]

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Numerical Models

RHS Joints shell elements SHELL281

beam member plates mid-surfaces

Material multi-linear s x e

Geometrical Non-linearity (Updated Lagrangian) (Identification of yielded points)

X

Feng & Young

Experiments

Section (h x b x t) E sp s0.1 sy= s0.2 s0.5 s1.0 su ef (%)

Chord 160x80x3 208000 167 481 536 570 595 766 40 Brace 40x40x2 216000 164 633 707 748 780 827 29

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Numerical Model Calibration

Experimental results Feng &Young

0

20

40

60

80

100

120

0 5 10 15 20 25 30 35 40

Load

[kN

]

Displacement [mm]

Numerical

Experimental

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Parametrical Analysis

Duplex stainless steel beams – LTB

W300x150 welded profile → 300mm height,

160mm flange width, 9.5mm flange thickness

&4.7mm web thickness

8 span lengths → from 1 to 8m corresponding →

lLT between 0.57 & 3.15

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Parametrical Analysis

Duplex stainless steel beams – LTB

0.00

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50

M/Mpl

lLT

Eurocode 3

Numerical - Ansys

Numerical versus Eurocode 3

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Parametrical Analysis

Duplex stainless steel beams – LTB

0

10

20

30

40

50

60

70

0 5 10 15 20 25

app

lied

be

nd

ing

mo

me

nt

[kN

]

vertical displcament [mm]

Ultimate bending moment = 57.64 kN.m

von Mises stress distribution (in MPa) →

observed → plastic bending moment

resistance → not reached in this case,

i.e., 479.61 kN.m

Adopted yield stress for → duplex

stainless steel → 526.68 MPa

7m span

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Parametrical Analysis

RHS duplex stainless steel joints

Model ID

Geometry

Chord Brace β 2

h0 b0 t0 h1 b1 t1

1 160.5 80.6 2.96 40.1 40.3 1.96 0.50 27.23

2 160.5 80.6 3.26 40.1 40.3 1.96 0.50 24.72

3 160.5 100.6 2.96 40.1 40.3 1.96 0.40 33.99

4 160.5 100.6 3.26 40.1 40.3 1.96 0.40 30.86

5 160.5 120.6 2.96 40.1 40.3 1.96 0.33 40.74

6 160.5 120.6 3.26 40.1 40.3 1.96 0.33 36.99

7 160.5 140.6 2.96 40.1 40.3 1.96 0.29 47.50

8 160.5 140.6 3.26 40.1 40.3 1.96 0.29 43.13

9 160.5 150.6 2.96 40.1 40.3 1.96 0.27 50.88

10 160.5 150.6 3.26 40.1 40.3 1.96 0.27 46.20

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Parametrical Analysis

RHS duplex stainless steel joints

Model

ID Nu Ns Nu/Ns Ndef N1,Rd N1

* N1np

1 47.4 32.4 1.5 47.4 35.6 32.3 28.7 0.8 0.7 0.6

2 59.1 41.0 1.4 59.1 43.1 39.2 36.1 0.7 0.7 0.6

3 30.7 18.1 1.7 27.1 30.2 27.5 22.2 1.1 1.0 0.8

4 38.0 22.9 1.7 34.4 36.6 33.3 28.1 1.1 1.0 0.8

5 23.3 12.2 1.9 18.2 27.5 24.9 18.1 1.5 1.4 1.0

6 29.2 15.6 1.9 23.4 33.3 30.3 23.3 1.4 1.3 1.0

7 19.5 8.8 2.2 13.3 25.7 23.4 15.0 1.9 1.8 1.1

8 24.4 11.5 2.1 17.3 31.2 28.4 19.7 1.8 1.6 1.1

9 18.2 7.7 2.3 11.6 25.1 22.8 13.7 2.2 2.0 1.2

10 22.7 10.1 2.2 15.2 30.4 27.7 18.2 2.0 1.8 1.2

def

Rd,1

N

N

def

*

1

N

N

def

np1

N

N

EC3 CIDECT Feng & Young

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Final Remarks

Present paper → evaluation → lateral buckling

capacity of duplex stainless steel beams → &

resistance → tubular T joints between RHS

members → constituted → duplex stainless steel

Results → discussed & compared → stress

distribution, force-displacement curves, etc.

Numerical & analytical curves → LTB beams

analysis → Eurocode 3 equations related → these

ULS for carbon steel beams → can also be used for

duplex stainless steel profiles

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Final Remarks

RHS joints, → new CIDECT formulation → better

approximation → numerical results → when

compared with Eurocode 3 results

When these two values → compared with the Feng

and Young values, → concluded → this formulation

presented → better results → when compared →

two first ones.

Acknowledgements: CAPES, CNPq, FAPERJ and

UERJ financial support provided to enable the

development of this work

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Acknowledgements

Thanks for your attention

Contacts: vellasco@uerj.br and lucianolima@uerj.br