Estimating in Building Construction

(Barré) #1
Concrete 95

FIGURE 10.6.Volume in Bells 50-Degree Angle (top) and 60-Degree Angle (bottom).

EXAMPLE 10–3 DRILLED PIER


From the small commercial building example found in Appendix A,
there are three identical drilled piers with the following dimensions:


Shaft diameter 18 inches
Bell diameter 42 inches
Angle of bell 60 degrees

Formula 10-1

Height of Bell on Reamed Footing

Formula 10-2

Height of Bell on Reamed Footing
From the given dimensions the bell height is

or


H1.732¿

Htan(60°)a

3.5¿1.5¿
2
b

H1.732–

H

sin(60°)a
3.5¿1.5¿
2
b

sin(90°60°)

Htan(A)a
B 5
2

b

H

sin(A)
B 5
2
sin(90A)

Once the bell height (H) is found, Formula 10-3 or 10-4 can be
used to determine the volume of the belled portion of the footing.

Formula 10-3

Volume of Bell

Formula 10-4

Volume of Bell
The bell volume is as follows:

or

Volume of bell8.96 cf

Volume of bell

1.732¿
12
(1.5¿^2 3.5¿^2 1.5¿3.5¿)

Volume of bell
H
12
(S^2 B^2 SB)

Volume of bell8.96 cf

a

3.5¿1.5¿)1.732¿
4
bbb

a 2 aa

(21.5¿)3.5¿
6
Volume of bella b
1.5¿^2 1.732¿
4
b

Volume of bell
H
12

(S^2 B^2 SB)

a

(BS)H
4
bbb

Volume of bella
S^2 H
4
ba 2 aa
2 SB
6
b
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