73 floor building , model does not show the modes when using Ritz vectors

[ramiibrahim]

I have received an ETABS model from the consultant but when I try to run the model using the Ritz vector it does not give me any mode shape but when I changed the Modal into Eigen I got the mode shapes and periods . any reasons for this issue ?

 

[ilyas415]

Have any errors/warnings been output from the analysis?

What loads have been defined for the Ritz Vector modal analysis case?

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Ilyas