Modeling braced frame with truss element

[amy]

Thank you sir. The problem with the model in the truss element is that when I divide the bracing into four elements using truss element to model initial imperfection for buckling, the model doesn't work. I think in SeismoStruct I can not divide the truss element.
So now I am trying to model the bracing with infrmFB element connected to the joint with link . I will let you know if it works for me.
Thanks
Amy

[roshen.rj]

Hi

I have a similar problem. I am trying to release the moments on my bracings in a 4 storey buildings. But I am not able to run the analysis in the Pushover analysis with M2a, M3a.. etc releases. I have tried different convergence criteria referring to seismostruct video on convergence error but without any luck . The model works in an Eigen value analysis

The type of elements that I have used for my bracings are - elastic, infrmDB (both with releases) and truss elements. But none of them seems to work. What are some suggestions that you can give?

Thanks

[seismosoft]

Using frame inelastic elements with releases in the moments at its two edges generally leads to numerical instabilities. Consider either using an elastic elfrm element with releases or a truss element for the braces.
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[roshen.rj]

Yes, I have tried both the options as I mentioned above and still the convergence error occurs.

[seismosoft]

Follow the guidelines that are provided in the relevant section on the manual. Running an eigenvalue analysis will also give you good insight.
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[roshen.rj]

I have actually started from the Eigen value analysis and it is only when I release the moments that the convergence problem occurs. The model works perfectly without the releases. I have also read the manual and the chapter on 'Tips to solve convergence problems'. I have done all the different steps one by one like increasing convergence norms etc. but I am still not able run the model. It starts to fail after 4-5mm in a Pushover Analysis.

[seismosoft]

Can it be that the structure has actually failed? Check in the post-processor in the Convergence tab the element or location where the divergence problems occur and then check the inelastic response of these elements.
Note also that in the case of a brace that is divided in several elements, only the start of the first and the end of the last elements need to have releases
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