Introduction to the Drafting of the ... - steel-stainless.org · Introduction Stainless steel...
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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
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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
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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.
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Roof boarding
Stadium of Asian Games-Guangzhou, 2010
B445R
304
B445R-external decorative
panel;
304-waterproofing panel
and keel
304
Introduction
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Bearing component
Human and Nature Museum-Kunming, 1999
Introduction
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Fragmentary Lotus Leaf
Introduction
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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
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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.
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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
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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
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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
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Material model
Nonlinear property and low proportional limit
Considerable strain hardening after yield
High elongation
Hundreds of material tests were conducted.
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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
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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
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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
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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
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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
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Reliability index
Curve C: 3.84
Buckling resistance of columns
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Single symmetric
Double symmetric
14 welded H section
beams were tested.
Buckling resistance of beams
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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
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Buckling resistance of beams
The proposed curve is similar to that in Eurocode.
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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
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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
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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
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Residual stress
Residual stresses in welded H section were measured using Sectioning Method.
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Proposed model of residual stress
Flange
Web
Residual stress
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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
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Thank you for your attention!