Question

The nominal live load for a four-story commercial building is 80 lb/ft2. The vertical load resisting system consists of flat plate floor slabs supported by a grid of columns spaced 25 ft in one plan direction and 20 ft in the other plan direction. What is the service live load for a first floor interior column, reduced according to ASCE-7 guidelines

Answer 1

Answer:

106 kips

Explanation:

Determine the service live load for a first floor interior column

following ASCE-7  guidelines

Area = 20 * 25 = 500 ft^2 which is > 400 ft^2

Nominal live load on every floor = 80 psf

Hence the reduced service live load ( L )

L = Lo [ 0.25 + 15 / √AI ]  ------ ( 1 )

Lo = unreduced load

AT = Tributary area = 500 * number of floors = 2000 ft^2

AI ( influence area ) = AT * number of floors = 2000 * 4 = 8000 ft^2

Lo = 1.6 * 80 psf * 2000 ft^2 = 256 kips

Input values into equation 1 above

L = 106 kips