Question

Consider a 6 story building with a total plan area B x L. Which B=100ft and L=60ft. The average weight of each floor and roof are 100lb/ft2 and 80lb/ft2, respectively. The 72ft tall building is located in a seismic region with S_DS= 1.0g and S_D1= 0.7 for a building supported on rock, where g is the gravitational acceleration. The structure of the building consists of steel moment frames (all joints are rigid) that have R value of 8. The importance factor 1.1. Determine the total design seismic force (kips) acting at the base of the building (seismic base shear in kips).

Answer 1

Solution:-

Given

L= 60 feet

B = 100 feet

Floor weight = 100 lb/feet²

= 100*100*60 = 600 kips

Weight of roof = 80 lb/feet²

= 80*100*60 = 480 kips

Total weight of building(W) = 5*600 + 480 = 3480 kips

Design base shear (V_B) = A_h*W

Horizontal seismic coefficient (A_h) = Z/2 * I/R *S_a/g

= 0.24/2*1.1/8 *1 = 0.0165

Total seismic design base shear(V_B) = A_h*W

= 0.0165 * 3480

V_B = 57.42 kips   Answer