Maximum Stress on Shell element in Ultimate Limit State Design Method

[Canada580]

IF we design a plate based on ultimate limit state method, the stress on shell element with elastic model on SAP2000 can give higher stress value than yield stress. To compare design approach and modeling approach, may be we need to model the plate using layer nonlinear shell element.

However, if I am modeling a rectangular plate, the plastic section modulus is 1.5 times higher than elastic section modulus. Can I simply check that the maximum stress on plate element is not higher than 1.5 times yield stress? If so, how should I check and compared the maximum stress results from SAP2000 when I am modeling a circular plate?

Any help please!

 

[Agent666]

Probably ok for a rough guage for strength, but not for assessing deflection I would have thought. Stiffness changes after yield. As soon as you are over the yield stress you are into nonlinear effects such as strain hardening and plastic deformation.

 

[Agent666]

Build a simple model like a simply supported plate using both elements and see if there is a difference and report back?