Seismosoft | Earthquake Engineering Solutions

Dear Madam/Sir,

I was trying to verify an experimental work from a literature with a model in seismostruct. The result for yield displacement and base shear(pushover analysis) is 23mm and 275kN respectively. I obtained 20mm and 280 kN. Also for near collapse (rotation capacity) displacement and base shear values are 122mm, 361kN(experimental) and 116mm,351kN(my model results)
The results are quite satisfactory. However to obtain the yield and rotation capacity I had to change the steel material strength.
In the experimental data, the reinforcement strength were fy = 448 N/mm2; fu = 731N/mm2; concrete strength fck = 27.6N/mm2
I have used stl_mp model and conc_ma models
for stl_mp when I use mean(or yield) strength = 448000kPa I get the above yield response, however, the NC responses are 112mm,243kN
Again when I use mean(or yield) strength = 731000kPa I get the above NC response, however, the yield responses are 36mm,393kN

May be I am missing something, please provide your valuable guidance. May be somewhere both yield and ultimate strength can be assigned but m not able to get it well?

thanking you,

with warm regards,
Karabi

Can it be that you are confusing the mean response with the mean material values with the capacities obtained with characteristic material strengths, with partial material factors and other safet factors? The code-based capacities are always more conservative.
Seismosoft Support

thanks a lot for your response. However, may be I was unable to give a proper explanation of the problem I was facing. Would you please provide me some guidance how to provide the ultimate strength of steel in stl_mp model? In the model I can find yield strength (mean strength = yield strength by default) and lower bound value which is mean- standard deviation.
thanking You,

with warm regards,
Karabi

From the help system description of the subject steel material model you will find that the tensile strength, fult, is related to the other parameters through the strain hardening parameter, mu.

"Strain hardening parameter - mu
This is the ratio between the post-yield stiffness (Esp) and the initial elastic stiffness (Es) of the material. The former is defined as Esp=(fult-fy)/(-fy/Es), where fult and represent the ultimate or maximum stress and strain capacity of the material, respectively. Its value commonly ranges from 0.005 to 0.015. The default value is 0.005."