yield strength

[zhwang]

To whom it may concern,
I select stl_bl for bare steel frame, and if I set the yield strength to 100 MPa, I can get very good hysteretic curves by comparing simulation results with experimental results. However, if I set the yield stregnth to 340 MPa, the max force of simulation is 15KN larger than that of experimental results. Is it reasonable for me to set the yield strength to 100 MPa? Thanks.

Summer

[huffte]

I am not completely clear on the question. What is your real estimated yield strength for the steel used in the experiment? I think the real value is what you will need to use. If you have to specify a fake yield stress in order to make results match, then I would look at the details of the model and pinpoint other differences.

[zhwang]

Hi Huffte,

The real estimated yield strength should be about 340 MPa. I have attached my model to your email: Tim.Huff@tn.gov.
Thanks for your help.

[huffte]

I don't see any justification for arbitrarily adjusting Fy in order to make model results match the experimental results. There must be some boundary condition / restraint differences between the two which will need to be pinpointed and resolved. It would seem that it takes about 3.4 times as much load to yield your model compared to experimental results expected from your description. Therefore, it would appear that your model is much more strong/stiff than the experimental setup. I would start looking for issues - base fixities, connection releases, etc. . - in the model which may be physically distinct from the as-built experimental details.

Best of luck, zhwang.