Applies To
	Product(s):	STAAD.Pro
	Version(s):	All
	Environment:	N/A
	Area:	STAAD.Pro Analysis Solutions
	Subarea:	Seismic Analysis
	Original Author:	Abhisek Mandal, Bentley technical Support Group

 Can STAAD automatically calculate the seismic forces both in horizontal and vertical direction required by ASCE as shown next

E = (Rho) x Q_E (+/-) 0.2 x S_DS x D

As per section 12.4.2 of ASCE 7-10,

 

E = E_h + E_v

 

and

 

E = E_h – E_v

 

where

 

E_h = ρ * Q_E (equation 12.4-3 of ASCE 7-10) is the Horizontal seismic load effect

 

and

 

E_v =  0.2 * S_DS * D  is the vertical seismic load effect described in equation 12.4-4

 

STAAD calculates only the Q_E term of the horizontal component E_h. The user has to manually multiply Q_E by ρ to obtain E_h. There is no provision in STAAD to input ρ, which is defined in section 12.3.4.2 as a redundancy factor for Seismic Design categories D through F.

 

STAAD does not calculate the vertical component E_v. However as indicated above, Ev can be calculated based S_DS and D. The effect then can be included by appropriately modifying the load combinations.  

 

SELFWEIGHT Y 0.036