The combined response for the modal base shear (Vt) is compared with the calculated base shear (V) using the equivalent lateral force procedure automatically. If ıt’s less than 100% of the calculated base shear (V) using the equivalent lateral force procedure, the forces is multiplied by V∕Vt automatically.
Where the combined response for the modal base shear (Vt) is less than CsW, drifts is multiplied by CsW∕Vt automatically.
Symbols
V = The equivalent lateral force procedure base shear
Vt = The base shear from the required modal combination
A base shear (V) is calculated in each of the two orthogonal horizontal directions using the calculated fundamental period of the structure T in each direction and the procedures of Section 12.8.
12.9.1.4.1 Scaling of Forces
Where the calculated fundamental period exceeds CuTa in a given direction, CuTa is used in lieu of T in that direction. Where the combined response for the modal base shear (Vt) is less than 100% of the calculated base shear (V) using the equivalent lateral force procedure, the forces is multiplied by V∕Vt
12.9.1.4.2 Scaling of Drifts
Where the combined response for the modal base shear (Vt) is less than CsW, and where Cs is determined with Eq. (12.8-6), drifts are multiplied by CsW∕Vt.