Eigenvalue and Pushover analyses

[nader28143]

Dear All,

Before doing a pushover analysis I did an eigenvalue analysis to verify the modal frequencies and mode shapes of the model. I specified the mass source to be from both element masses and additional mass elements. When I did the pushover analysis, I looked at the eigenvalue results and found it totally different from what I had before (from previous separate eigenvalue analysis). I am wondering why would it be so different? is the mass source different for pushover analysis? Please let me know.

Sincerely,
Nader

[z.gronti]

Dear nader28143,

Could you please check if you define the mass in the same way in both files? You should have selected in both files the i)From the Frame Elements and Mass Elements or iii)From both Frame/Mass Elements and Loads. If you have defined the mass in the same way in both files, could you please send us your file at z.gronti@seismosoft.com to check it?

[nader28143]

Dear Zoi,

Thanks for your quick reply!

I took a copy of the same pushover model and changed the analysis type to eigenvalue analysis. Thus, everything is identical. However, I am still getting totally different modal frequencies and mode shapes from the two analyses!! I will send the two models to your email. Many thanks in advance.

Best Regards,
Nader Aly

[z.gronti]

Dear nader28143,

We have looked into the models that you sent us and we found out that there is a bug in the program.
The bug will be fixed in the next release of SeismoStruct 2016, which will be published next week.
Thank you for this bug report.