Potential bug with NP EN 1998 spectra

[brisid.isufi]

I am using the NP EN 1998-1 spectra in my model, but I noticed that the results do not match my hand calculations. So, I decided to run a spectral analysis in which I define the spectrum manually and the results now match my hand calculations. I might have made a mistake somewhere, but I checked several times and this does look like a bug to me. Could someone please take a closer look? I will provide more details below. 

This is my model:

and these are the loads:

This is how I applied seismic loading:

Then I built the code spectrum on my own for comparison:

When I run the analysis, I get these shear forces for the automatic spectrum:

and these for the manually defined spectrum:

The sum of shear forces from the manually defined spectrum matches my hand calculations pretty closely:

Is there a way I could see the automatically defined spectrum? Could someone please look into this? I am attaching my model. 

Thanks!

[brisid.isufi · Accepted solution]

I am sorry, I was wrong and I found my error. It had to do with the importance class. I was using Importance Class I while thinking of Importance Class II.

I also found out how to see the response spectrum: Analysis - Calculation Notes.