SAP 2000 modelling problem

[pujan73]

I am modelling 6 storied building , during analysis my sap2000
i found that above 5th floor i.e at roof level earthquake load in not involved in the analysis. only gravity load takes part in analysis. i have modeled building for many times, up to 5th floor is okay, above it, lateral load does not take part in analysis, neither it gives base shear. Only 5th floor of building contributes base shear. please help me to solve this problem.

Thanks.

 

[Nonlinearer]

If you are using Auto seismic case, just check your story range under "Modify lateral load" tab; it should be roof.

IR

 

[Nonlinearer]

Story means.....lateral load elevation range which should include your roof (max 'Z'.
Also check your roof loading should be included in mass source for seismic load.

IR

 

[pujan73]

Thanks for reply,

I have not used auto seismic case. I have calculated total seismic wt. of building, base shear and calculated the EQ loads and applied it as rigid floor diaphragm . How can i check for lateral load elevation range? Please find the attached file and help me.


Thanks.

 

[Nonlinearer]

I have tried on your model. The only way when the Roof story shows the earthquake forces is to use Auto seismic load pattern under load pattern tab. Under Auto seismic, you can clearly define the height range. I have checked and it works. Probably, it requires more time to find out why the top story doesn't show the EQ forces as per your manual input method.

IR

 

[pujan73]

Thank you so much.

Pujan Neupane