(3) Soil data available:
Description - Gravel
Compaction - Medium
Blow count - 40
Allowable bearing pressure - 5 tons/ft2
(4) Design strength for building materials:
Concrete, f'c = 4,000 psi
Steel, fy = 60,000 psi
Solution:
(1) Estimate the dimensions of the foundation extension to be
used in the overturning analysis.
Thickness of wall: (TW) = 6.25 ft
Height of wall: (HW) = 16.25 ft
Estimated thickness of foundation extension:
TS = 1.25(TW)
= 1.25(6.25)
= 7.81 ft
Use 7.83 ft = 7 feet 10 inches
Estimated length of foundation extension:
LF = 0.45(HW)
= 0.45(16.25)
= 7.31 ft
Use 7.5 ft = 7 feet 6 inches
For an efficient design, the foundation should be
symmetrical about the centerline of the wall.
(2) Determine the soil bearing pressure for the weight of the
structure.
Estimate weight of structure:
Ws = 16.25(6.25) + [2(7.5) + 6.25](7.83)(52)150
2,000
= 1,045 T
2.08-318