Introduction to the Drafting of the Design Code

for Stainless Steel Structures

in China

Fourth International Experts Seminar

Stainless Steel in Structures

Ganping SHU

Baofeng ZHEN Shenggang FAN

Southeast University,

Nanjing, China

Dec 7 2012, Ascot, UK

OUTLINE

Introduction

Scope of stainless steel structures design code

Grades and properties of materials

Buckling resistance of column, beam & plate in

compression

Residual stress

Some researches undergoing

Introduction

Stainless steel structures in China

• The stainless steel structures used in building increases

rapidly in recent years.

• Most of them are used as roof boarding, coating, and

interior decoration.

• The use of bearing components is limited because of the

relative high initial investment and the lack of design

code.

• Stainless steel members are mainly used as bearing

components in grid structures.

• There is a growing trend to use stainless steel in other

types of structures.

Roof boarding

Stadium of Asian Games-Guangzhou, 2010

B445R

304

B445R-external decorative

panel;

304-waterproofing panel

and keel

304

Introduction

Bearing component

Human and Nature Museum-Kunming, 1999

Introduction

Fragmentary Lotus Leaf

Introduction

The researches on stainless steel structures began in

2005. The first version of the design code for stainless

steel structures is under drafting. It will probably be

published in 2013.

For the drafting of the code, lots of researches have

been conducted according to the practice in China.

Introduction

Scope of stainless steel design code

As most of stainless steel members used now are

thin-walled members, the scope of the design

code for stainless steel structures is similar to

Technical code of cold-formed thin-wall steel

structures GB50018-2002.

Tests have been finished Tests are being prepared

Chapter 1: General provisions

Chapter 2: Symbols and definitions

Chapter 3: Materials

Chapter 4: Basic requirements

Chapter 5: Members and elements

Chapter 6: Connection design

Chapter 7: Corrosion and fire resistance

Chapter 8: Manufacture and installation

Scope of stainless steel design code

Focused on in this presentation

Chapter 1: General provisions

Chapter 2: Symbols and definitions

Chapter 3: Materials

Chapter 4: Basic requirements

Chapter 5: Members and elements

Chapter 6: Connection design

Chapter 7: Corrosion and fire resistance

Chapter 8: Manufacture and installation

Scope of stainless steel design code

Grades of stainless steel

Referring to the material standards and the actual

supply in China , the following 5 types of stainless

steel are recommended in the code.

Austenitic: S30408, S30403(304L), S31608,

S31603(316L)

Duplex : S22053

Material model

Nonlinear property and low proportional limit

Considerable strain hardening after yield

High elongation

Hundreds of material tests were conducted.

Considering the limit stress in practical design,

Ramberg-Osgood model is recommended in the

code.

0 0.2

0.002

n

E

Parameters： 0E 0.2 n

Material model

Unavailable in

material standards

GB/T 4237-2007 and

GB/T 3280-2007

Different among grades;

Effected by cold work

Values in

Eurocode are

basically adopted

Buckling resistance of columns

Load cell

7 SHS specimens, 13 RHS specimens, 11CHS

specimens and 7 welded-H specimens were tested.

Tes

t ri

g

Load Cell

Knife Edge

LVDT(3)

LVDT(4)

Screw Jack

Knife Edge

LVDT(1)

LVDT(4)

Columns of the

Specimens

test machine

test machine

单刀铰

Effect of strain

hardening exponent n

Effect of nondimensional

proof stress e

Finite element analyses were conducted covering the

range of common material and slenderness.

The effects of e and n on the strength curves

should be considered in the design code

Buckling resistance of columns

Section types

A: SHS and RHS 0.60 0.56

B: CHS and C 0.36 0.0

C: Welded H 0.76 0.20

0

2 2

11

2

00.5[1 ]

Based on the tests and finite element analysis, three

design curves are recommended

Buckling resistance of columns

Curve B: 3.38

Reliability index

Curve A : 3.50

Tensile strength is

used in calculating the

test reduction factor

NOTE

Buckling resistance of columns

Reliability index

Curve C: 3.84

Buckling resistance of columns

Single symmetric

Double symmetric

14 welded H section

beams were tested.

Buckling resistance of beams

𝜑 =1

𝜙 + 𝜙2 − 𝜆 2≤ 1

𝜙 = 0.5 1 + 𝛼 𝜆 − 𝜆0 + 𝜆 2

𝛼 = 0.65; 𝜆0=0.41

Buckling resistance of beams

Buckling resistance of beams

The proposed curve is similar to that in Eurocode.

68 stub columns were tested

including cold-formed

hollow sections, open

sections and welded-H

sections

Welded H CHS Lipped C

SH

S a

nd

RH

S

Buckling strength of plate in compression

Finite element analyses were conducted covering the

range of common material and slenderness

Effect of strain

hardening exponent n

Effect of nondimensional

proof stress e

The effect of e is larger than that of n on the

strength curves

Buckling strength of plate in compression

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.00.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

=/(E*+F)

=(E*+F)/

=A+B*^0.5

r

edu

ctio

n f

acto

r

slendness

Three-stage strength

curve is recommended.

The effect of n can be

neglected.

Buckling strength of plate in compression

Residual stress

Residual stresses in welded H section were measured using Sectioning Method.

Proposed model of residual stress

Flange

Web

Residual stress

Research undergoing

Tests under prepared

• Buckling resistance of beam-columns

• Behaviors of column in fire

Theories

• The mechanism of strength enhancement after cold

forming and its effect on the behaviors of members

• The design method based on Direct Strength Method

Thank you for your attention!