question about infill wall model in sap2000

[mig21]

hi

what is the purpose of your study ? its academic or a real project ?

in my point of view considering the infill in ultimate limit state, unless you design the infill as a structural element ( reinforced masonry ) it's agings safety. in the design (ultimate state) earthquake after a few shaking cycles the infill will be cracked and the infill will stop to contribute to the response of the building. although in service limit state - damage limitations i think you can consider their behavior. more ,, consider only the outer infill's neglect the interior infill's since they can be removed in future building works.

regards

[abouferass88]

hi

it is academic study and i have considered only the exterior infill wall

i modelled the infill walls as suggested by our colleague "adekajeng" but i have problem with the solution convergence in sap2000. it didnt finish the analysis.
i have tried to change some prameters in pushover load case and get the same non-convergence solution

also i have one more question about the monitored displacement in sap2000 for the pushover analysis, i think it has contibution in getting the solution convergence ?! any suggestion to choose appropriate value.


Regards

[Sumatra]

hi,

just want to share the key-steps needed for pusover analysis using sap2000.

1. in dead load case, from linear change to nonlinear of analysis type. the rest parameters no need to change.

2. in pushover case, select Continue from State at End of Nonlinear Case (DEAD) in Initial Conditions > Select Nonlinear in Analysis Type > Add LATERAL LOAD in Load Name of Loads Applied > Modify/Show in Load Application of Other Parameters > Select Displacement Control in Load Application Control > Select Use Monitored Displacement in Control Displacement > Fill in displacement magnitude (e.g. 10% total height of structure is fairly enough). Use the corner joint at roof top or top story for Monitored Displacement.
Normally, displacement magnitude will be set automatically by sap2000 and the value is commonly sufficient.

3. In pushover case, Modify/Show in Result Saved of Other Parameters > Select Multiple States in Result Saved > OK > Modify/Show in Nonlinear Parameters of Other Parameters > Select Apply Local Redistribution in Hinge Unloading Method > OK.

Tips: If your intention is seismic evaluation, pls use small quantity of lateral force (e.g. max 1kN at the top floor). Dont worry if you find the following warning because program just want to inform you that the lateral stiffness is already close to zero and analysis must be terminated.



Hope it will solve your non-convergence problem. :hunter:

Regards,
adekajeng

[abouferass88]

hi adekajeng

what did you man by " If your intention is seismic evaluation, pls use small quantity of lateral force (e.g. max 1kN at the top floor). " is this lateral force in addition to the pushover load pattern.

i will change the parameters as you suggested and hope that converge the solution

regards

[Sumatra]

hi abouferass88

as we knew there are 2 main purposes of performance-based seismic engineering for building namely seismic design & seismic evaluation. the first needs the lateral force based on design spectrum for pushover analysis so that the capacity and demand spectrum can be generated, whereas the second may be capacity evaluation only, which means we could push the building till instability occurs, regardless what design spectrum governed.

cheers,
adekajeng