Design Considerations for Earthquake Forces - Simplified Design of Reinforced Concrete Buildings - page 286

F x = C vx V

w x h k

C vx =

n
∑

w i h i k

i = 1

where:

F x = lateral force at floor level x
C vx = vertical distribution factor for level x
k = a distribution exponent related to the building period T
= 1 for T ≤ 0.5 second
= 2 for T ≥ 2.5 second
= 2 for 0.5 second < T < 2.5 second, or linear interpolation between 1 and 2

1.1

1

0.9

0.8

0.7

0.6

0.5

0.4

0.3

0.2

0.1

0

10 20 30 40 50 60 70 80 90 100

Building Height h, ft.

Figure 11-8 Fundamental Period for Reinforced Concrete Buildings