Differences calculating the Base Shear

[psi_14]

Hello everybody,

I have a question concerning the masses of the floors to do a pushover analysis.

I want to calculate the Base Shear to know the incremental lateral forces to apply in my structure according to EC8 spectrum that I previously defined.

In the settings I selected the mass from both frame/mass elements and loads and then sum the masses of the nodes of each floor so I could have the masses of the floors to multiply for my eigenvalues. From other software I have very different reaction in Z direction (even discounting the coefficients) to permanent loads. The masses that I took from seismostruct are approximate from the total support force in Z direction. Did I make any mistake here or this is the correct way to calculate the masses of the floor? It could be just some diference between softwares or my modeling.

Cheers

[seismosoft]

Unless there is a significant bug in either SeismoStruct or your other software (which is not very likely to be honest, since these programs have been thoroughly tested in the past) you are probably making a mistake in the calculation of forces.
A good thing to do at first is to check the total reactions of your buildings under static loading in both programs. Normally, you should get the same total reaction forces.
Seismosoft Support