Design of square footing for a single column - Reinforced Concrete with FRP Bars: Mechanics and Design - page 361

10.4 STEP 2—COMPUTE SERVICE AXIAL
LOADS AND BENDING MOMENTS

The axial forces and bottom moments of column B3 (see Chapter 9) are the
forces to be considered for design of the footing. Analysis results per single
load case are

Dead load (D): Live load (L): Wind (W):

P D := 190 kip P L := 124 kip P W := -35 kip

M D := 32 kip·ft M L := 0 kip·ft M W := 91 kip·ft

Analysis results per load combination are

• Load combination 1: D
P S1 := P D = 190·kip
M S1 := M D = 32·kip·fit
• Load combination 2: D + L
P S2 := P D + P L = 314·kip
M S2 := M D + M L = 32·kip·ft
• Load combination 3: D + L + W
P S3 := P D + P L + P W = 279·kip
M S3 := M D + M L + M W = 123·kip·ft

10.5 STEP 3—PRELIMINARY ANALYSIS

10.5.1 Design footing base area
To estimate the weight of soil and concrete above footing base, it was
assumed that average density was

ρ soil := 130 pcf

An additional surcharge due to the loads on the ground floor is considered:

s additional := 100 psf

Foundation base depth is

z := 5 ft

The total pressure of surcharge at the foundation base depth is

s total := ρ soil ·z + s additional = 750·psf

The permissible soil pressure is

σ adm := 4000 psf