Civil Engineering Reference
In-Depth Information
l
brg
=
length of bearingarea, in
t
studs
=
thicknessofend studs, in
±
∑
VH
M
DL
F
=
overturningforce
,
usingappro
priate load case factors
ot
/
x
V
= applied lateral force, lb or k
H
= height of wall, ft
∑
M
DL
=
sumofresisting dead load moments
Shear walls are required to be designed for the following load combinations, in
accordance with IBC Section 1605 and ASCE 7-05,
Minimum Design Loads for Buildings
and Other Structures
.
7
Assuming that
H
,
F
, and
T
do not apply, the load combinations
relevant to this topic are as follows:
Strength design, ASCE 7-05 Section 2.3.2 (see exceptions)
The 1.0 factor for
E
is based on the more recent NEHRP research on seismic resistant
design.
8
ASCE 7-05:
3. 1.2
D
+ 1.6(
L
r
or
S
or
R
) + (
L
or 0.8
W
)
4. 1.2
D
+ 1.6
W
+
L
+ 0.5(
L
r
or
S
or
R
)
5. 1.2
D
+ 1.0
E
+
L
+ 0.2
S
6. 0.9
D
+ 1.6
W
7. 0.9
D
+ 1.0
E
Allowable stress design, ASCE 7-05 Section 2.4.1 (see exceptions):
ASCE 7-05:
5.
D
+ (
W
or 0.7
E
)
6.
D
+ 0.75
L
+0.75(
W
or 0.7
E
) + 0.75(
L
r
or
S
or
R
)
7. 0.6
D
+
W
8. 0.6
D
+ 0.7
E
The calculation of shear wall deflections is important for the determination of
story drifts, the design of open front diaphragms, determining wall rigidities, and in
irregular-shaped diaphragm design. The shear wall deflection equations have been
well documented in many publications. The four-term equation below was devel-
oped from static load tests on shear wall assemblies with aspect ratios of 2 : 1 or less.
The APA
1
noted that the equation was not as accurate for walls with aspect ratios
greater than 2 : 1.
3
dh
b
8
vh
EAb
vh
G
e
∆
SW
=
+
+
075
.
he
+
IBC Eq. 23-2
n
t
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