Civil Engineering Reference
In-Depth Information
Construction of the basic shear diagram (see Fig. 9.17):
wL
R
D
172 20
2
()
1720
24
1
1
R
=
=
=
1720
lb
vv
=
==
1
2
1
2
L
plfdiaphragm unit shear
=
71 67
.
wL
(
+
L
)
172 20
(
+
40
)
R
=
1
2
=
=
5160
lb
2
2
2
wL
R
D
172 40
2
()
3440
24
2
3
R
=
=
=
3440
lb
vv
=
==
3
2
3
2
R
=
143 3
.
plfdiaphragm unit shear
R
5160
12
v
== =
2
2
430
plfshear wall unit shear
SW
2
v
=- =- -
v
v
430
71 67
.
143 3
.
= +
215
plfnet un
it shearatshear wall
net
SW
iaph
Strut force diagram:
∑
F
=
L
v
=
12
(
-
71 67
.
-
143 3
.)
=-
2580
lb compression
strut
strut
diaph
FF
=
-
vL
=-
2580
+
215 12
()
=
0
lb
B
strut
netSW
Therefore, the diagram closes.
Shear panel forces (see Figs. 9.18 and 9.19):
v
panel
= 430
plfsameasshear wall
,
V
panel
=
430 2
()
=
860
lb
Assume the dead load of the roof is equal to 15 psf.
LL
(
DL
)
60 15 2
2
( ()
panel
DL
=
=
=
900
lb per
truss
truss
2
Vh
L
860 4
2
()
panelpanel
V
=
=
=
1720
lb ov
erturningforce at each endofpanel
side
panel
Load combination 0.6
D
+
W:
1
12
T
=
[
5160 4062
( )
-
. (
++++ +
4681012
)(
900
)
-
06480 6
.(
)( )]
=-
314
lb
Therefore, there is no overturning, and tie straps are not required at the ends of the
shear panels. This would not be the case if the panel height were greater than 4 ft.
▲
Three types of shear panels are commonly used and included in most typical detail
topics. Each of these details will be checked for capacity vs. demand for the previous
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