seismic forces

[proejuan]

Do the seismic forces act in the ortogonal directions at the same time or each one at diferent time?. This is for to do the calculations with combined the shear an tension forces or not.

 

[mrMikee]

proejuan,

Per the IBC the seismic forces up to and including Seismic Design Category B should be considered to act separately and independently in each of the orthogonal directions. In Seismic Design Category C and above the orthogonal combination of loads must be considered using either the SRSS or 100%/30% rule. In the IBC section 1620.3.2 describes this. The UBC has similar criteria.

Regards,
-Mike