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Distribution of seismic forces

Vertical distribution of seismic base shear:

Seismic base shear, V, is distributed to each floor level, according to the following equation (ASCE 7 eq. 12.8-11 & 12)


Where Fx is seismic shear force at each floor, Cvx is vertical distribution factor.

Vert distriution factor

Where wx is weight of each floor, hx is height of each floor, n is number of floor,

k is an exponent related to structure period, as

k = 1 for structure having a periord euqal or less than 0.5 second.

k = 2 for structure having a period greater or equal 2.5 second

k = 2 or by linear interpolation between 1 and 2 for period 0.5 second and 2.5 second.


Vert dist example