Performance criteria for steel braces

[hani.akkari]

dear seismosoft team,

i'm preparing my masters degree in studying the performance of concentrically steel braced frames under seismic loading. as you know the performance criteria that will be set for the braced frames is crucial for my study. i went through your help and i found it easy to set performance criteria for frame element but i'm very interested in the braces (in your help, only u can model an unelastic truss element without controlling its level of performance), because the plastic hinges are expected to appear in the braces for the dissipation of energy to happen , so monitoring the performance levels of the braces is very important for me, so how can i input perfomance checks (strain levels) for the brace elements ?(as it was possible in sap2000 software), waiting for your answer. thanks

[seismosoft]

Dear Hani Akkari,

We might have misunderstood your query, but if wish to model hinging in steel braces, then you should be using 'infrm' elements, rather than 'truss' ones, in which case performance criteria can indeed be set.

And, of course, independently of the setting or not of realtime-checked performance criteria, one can always post-process the results at the end of the analysis, in order to undertand how the structural members behaved.

Seismosoft Support

[hani.akkari]

Dear seismosoft,

thanks for your fast reply, but infrm is a frame element having moment and shear , so to model as a truss element we have to force its behaviour to axial force only,so how can we achieve this step?

regards,

[seismosoft]

Hani Akkari,

- in the current version, you need to introduce 'link elements' or 'constraints' at the ends of the infrm elements (search this forum for " truss infrm" for further discussion on this topic)

- in the upcoming release, the possibility of directly assigning end-releases will be available

Seismosoft Support

[hani.akkari]

Dear seismosoft,


thanks a lot for your reply , I really appreciate it.
my question now is the following :
the infrmFB element that i will use to define the truss elemet , i will set for it performance levels using seismostruct command by giving a strain value along with a colour to know the state of deformation in the element, but also when i inroduce the link element at the end of the infrmFB , i have also when defining the link elelemt to intoduce the curve type for F1 and that curve is a force displacement one, so what will be the relation between the strain levels that i will define for the infrmFB and the displacements from the force -displacement curve defined for F1?

Best regards,

Hani

[Sara]

Dear Hani Akkari,

the link element represents the hinge at the edge of your infrmFB, avoiding moment and shear transmission. Then this link should be characterized by high value of stiffness in dofF1 and zero stiffness for the other dofs.

Sara