Civil Engineering Reference
In-Depth Information
Factor of safety for overturning:
Overturning moment
(
P
AE
cos
) (
1
3
H
)
(
P
AE
sin
) (2)
(71.2 cos 32°) (
1
3
) (4)
(71.2 sin 32°) (2)
5.1
Moment of weights
56.4 (1)
56 (1.6)
146 kN
m/m
FS
146
____
5.1
29
10.5
Static analysis:
P
Q
QHk
A
200 (20) (0.297)
1190 lb/ft at 10 ft
P
QH
1190 cos
w
1190 cos 30°
1030 lb/ft
P
Qv
1190 sin
w
1190 sin 30°
595 lb/ft
N
15,270
595
15,870 lb/ft
P
H
5660
1030
6690 lb/ft
Factor of safety for sliding:
FS
N
tan
P
p
___________
Eq. (10.11) where
cv
30°
P
H
15,870 tan 30°
750
__________________
6690
1.48
Factor of safety for overturning:
Overturning moment
14,900
1030 (10)
595 (7)
21,030 ft
lb/ft
Moment of weight
55,500 ft
lb/ft
55,500
______
FS
21,030
2.64
Location of
N:
x
55,500
21,030
______________
15,870
2.17 ft
Middle third of the foundation:
x
2.33 to 4.67 ft, therefore
N
is not within the middle
third of the foundation.
Earthquake analysis:
Calculate
P
E
for surcharge (neglect wall friction):
a
max
____
g
k
h
0.20
