Seismic analysis floor definition

[Anonymous]

Hi,

In the attached model, I have defined the floors and roof as rigid diaphragm in order to transfer the seismic force to seismic force resisting systems. But why are the column base reactions all the same under gravity load? It doesn't seem right. the corner column and edge column reaction should be smaller than middle columns.

Thanks,

Peijing

[Rafal.Gaweda]

This is not real situation. These diaphragms makes your model to behave like a full solid body cantilever column.

You should use Shell calculation model of Slab Flexible Diaphragm model or such model:

[Anonymous]

Thanks, I have defined a new slab type as you described. The result is very good. So for regular building with concrete floor and metal deck roof we should consider node connection as flexible stiffening in XY.