Influence of Variation in Material Strength on Ultimate

Strength of

Stainless Steel Plates

under In-Plane Bending and Compression

Satoshi NARA

Osaka University

Yasuhiro MIYAZAKI Nagaoka National College of Technology

4th Internatonal Experts Seminar

6-7 December 2012, Ascot, UK

I saw Brocken spectre (Brocken bow) on the River Thames

just before landing to Heathrow.

Brocken spectre (Brocken bow)

at the top of a mountain

in an airplane

Japanese believes it is a sign of happiness. In fact, I met

Prof. Camotim, Prof. Rasmussen, Dr.Jandera supervised by

Prof. Machacek, and Dr.Rossi from University of Liege

where I had stayed and been hosted by Prof. Maquoi for

one year.

Outline of presentation

1 Background of the research

2 Material properties

3 Numerical analysis

4 Results and discussion

5 Conclusion

1.Background of the research

Stonecutters Bridge wikipedia: http://en.wikipedia.org/wiki/Stonecutters_Bridge

•Stainless steel has high

corrosion resistance

•Stainless steel bridge saves

costs and labor for

maintenance and

management

Design standards for steel and composite structures, in

which stainless steel is defined as a kind of structural steel,

has published by JSCE(Japan Society of Civil Engineers).

Two design standards has already specified by JSSC

(Japan Society of Steel Construction),

- for general building structures(1995),

- for light-weight stainless steel structures(2005).

The third design draft for civil structures is now in

preparation, and will be introduced in the JSCE design

standards.

However, 1) Expensive costs

Government pays construction costs of civil structures,

There are few who believe in low Life Cycle Costs(LCC). 2) No design standards for civil structures except for special ones

No alternatives to select stainless steel,

Small market still continues.

Moreover, 3) Circumstances of design codes

0.1% proof stress?

which is regulated by design standards for building structures,

0.2% proof stress?

which is specified by the Japan Industry Standards(JIS).

stainless steel design

method

•initial imperfection

•material properties unadapted

Simply supported stainless steel plate

ultimate strength

•uniaxial compression

•in-plane bending

Influence of variation in material

strength on ultimate strength

2.Material properties Type of stainless steel

Austenitic stainless steel

• SUS304

• SUS316

• SUS304N2

Ferritic stainless steel

• SUS410L

Duplex stainless steel

• SUS329J3L

Table 1 Statistical data of austenitic stainless steels

Table 2 5% and 95% fractile based on statistical data

Stress-strain model

Ramberg-Osgood curve

Where, ε and σ are strain and stress, respectively.

Fig.1 Stress-strain curves

Stre

ss

σ

(MP

a)

Strain ε

SUS329J3L_max

SUS329J3L_min

SUS329J3L_exp

SUS410L_max

SUS410L_min

SUS410L_expStr

ess

σ(M

Pa)

Fig.2 Stress-strain curves

3.Numerical analysis

Analytical plate models

Initial deflection

W0max : maximum value of initial deflection(=b/250)

a , b: unloading and loading length

Plate slenderness

k: buckling coefficient 4.0 for under uniaxial

compression, 23.9 for under in-plane bending

Uniaxial compression 4.Results and discussion

Fig.5 Comparison of ultimate compressive strength normarized

by the minimum proof stress

or

SUS410L_mat

SUS329J3L_mat

SUS410L_max

SUS329J3L_max

σ0.2

σ0.2_min

Fig.6 Comparison of ultimate compressive strength normarized

by the minimum proof stress

In-plane bending

Fig.8 Comparison of ultimate in-plane bending strength normarized

by the minimum proof stress

σ0.2

σ0.2_min

or

SUS410L_mat

SUS329J3L_mat

SUS410L_max

SUS329J3L_max

or

σ0.2

σ0.2_min

Mu

M0.2_min

Fig.9 Comparison of ultimate in-plane bending strength normarized

by the minimum proof stress

5. Conclusion (1) 95%

fractile of material strengths of

(1) SUS304, SUS316 and SUS304N2 based on

(2) statistical data is more than 97% of proof stress

0.2% specified by JIS.

(3) The maximum 0.2% proof stress is from 1.49 to

1.70 times higher than the minimum one, however,

the ultimate compressive and in-plane bending

strength of the plates with the maximum 0.2% proof

stress are 12% and 15% higher than those with the

minimum one, respectively.

Thank you for your kind attention!