Civil Engineering Reference
In-Depth Information
(3.39)
30
A
0
=
=
0.333
ft
2
3
1
l
c
+
(
)
(
)
0.643
10
0.888
12.5
(
)
()
6
+
1
6
2
3
100
×
20
×
10
i
20
i
20
δ
s
(
ft
)
=
0.96
0.333
×
2
−
3
×
0.9
×
+
1
×
3
×
216000
×
(3.40)
[
]
δ
s
(
ft
)
=
0.08897
×
2
−
6.075
×
10
−3
×
i
2
+
1.25
×
10
−4
×
i
3
The deflections computed using the equations are shown in Table 3.6 along
with deflections computed using FEM, every fifth floor. As expected, the
|
Error
%
|
are much larger than in Example 1, and increase from 18% at the top to 66% in
the lower quarter.
3.6.3 Rigidly Framed Earth Retaining Structure Subject to Earth
Pressure
Example 3 is a 4 story, 10 bay rigidly framed earth-retaining structure. The di-
mensions of the structure are shown in table 3.5. A retaining wall spans the width
of the structure to resist earth pressure. Earth Pressure loading is applied linearly
varying from 1480 psf at the bottom to zero at the top, resulting in a total load,
W
= 400 kips. The earth pressure corresponds to a soil density of 123 pcf and a coef-
ficient of lateral earth pressure of 0.33. The Equivalent Area,
A
o
and the lateral
drift,
, are computed according to Eq. 3.25 and 3.13 as follows in Eq. 3.41 and
3.42 respectively:
δ
(3.41)
2
3
400
×
4
×
9
i
4
7
8
×
i
4
δ
s
(
ft
)
=
1.17
0.3074
×
1
−
0
×
0.9
×
+−
3
×
216000
×
[
]
δ
s
(
ft
)
=
0.0846
×
1
−
0.010467
×
i
3
(3.42)
The deflections computed using the equations are shown in Table 3.6 along
with deflections computed using FEM at every floor. The
|
Error %
|
was reasona-
ble, being ≤ 7% again illustrating that the expressions yield reasonable results
when used within their intended range.
