Civil Engineering Reference
In-Depth Information
tan
1
a
max
____
tan
1
k
h
g
tan
1
0.20
11.3° Eq. (10.10)
w
24°
32°
0°
0°
Inserting the above values into the
k
AE
equation in Fig. 10.3 gives
K
AE
0.428
2
k
AE
H
2
P
AE
P
A
P
E
1
t
Eq. (10.9)
1
2
(0.428) (4
2
) (20)
68.5 kN/m
Resultant location of
N
and distance of
N
from the toe of footing:
N
weight of concrete wall
P
AE
sin 24°
35.3
32.9
68.5 sin 24°
96.1 kN/m
Take moments about the toe of the wall:
4
__
Nx
(
P
AE
cos
)
3
(
P
AE
sin
) (
e
)
W
(moment arms)
4
3
__
__
96.1
x
(68.5 cos 24°)
(68.5 sin 24°) (3)
35.3
32.9 (2.8)
3
2
x
145.5
_____
96.1
1.51 m
Maximum and minimum bearing pressures:
Since
N
is essentially at the center of
the footing,
q
q
N
B
96.1
__
____
3
32.0 kPa
Factor of safety for sliding:
N
tan
P
p
___________
P
AE
cos
FS
Eq. (10.16)
where
N
W
P
AE
sin
96.1 kN/m
FS
96.1 tan 38°
4.07
_________________
68.5 cos 24°
1.26
Factor of safety for overturning:
Overturning moment
(
P
AE
cos
) (
1
3
H)
(
P
AE
sin
) (3)
(68.5 cos 24°) (
1
3
) (4)
(68.5 sin 24°) (3)
0.15
therefore FS
