Non linear inelastic time history analysis in SAP2000 2

[samtronbn]

I am Modelling a 3 D 10 Storied Steel structure( Building) for seismic loading. I need to place dampers in the structures and the responses of the building are of critical importance. When i run a Non linear time history direct integration analysis for the structure, the responses i observe are in the inelastic range for the steel members, but the frame elements i choose were in the elastic range. So i get unreal responses for the structure. How can i get to account for inelasticity in my frame elemts and is SAP 2000 capable to handel Non linear inelastic analysis with responses accounting for inelasticity in the frame elements.

Regards,
Samtron

 

[jdgengineer]

SAP is capable of completing nonlinear analysis in the frame elements. The easiest way is to assign a Plastic hinge to your frame elements. Go to assign - frame - hinges. When you do this method you input a backbone curve for your nonlinear elements similar to how described in ASCE 41. In SAP this should be active for time history analysis, but only if you choose direct integration time history analysis (I think). This option from what I remember is not possible in ETABS when using time history analysis.

 

[samtronbn]

When i select the plastic hinge element for the frame element my analysis reports a warning: maximum number of steps reached for the load case and subsequent results will not be available.I am using P-M2-M3 hinge for steel columns table 5-6 from tables in FEMA 356. Can i get some help on that.
1.After the plastic hinge is formed all of the non linearity will be in the hinge formed, will the length of the hinge matter?
2. Are the displacements from a structure where plastic hinges are formed accurate enough.
3. My current research is on the placement of the passive energy dissipation devices, can the results from SAP 2000 Non linear inelastic analysis serve the purpose, are the results debatable.