Civil Engineering Reference
In-Depth Information
v
nominal
=
760
plfseismic
,
15/32
with 8d @4
o.c.
′′
′′
v
nominal
=
1280
plfseismic
,
15/32
′′
with 8d @
22o.c.
′′
Case 1- wind loading:
w
w
= 200 plf
w
==
200 50
2
()
R
=
5000
lb diaphragmreactionattgrid line1
2
h
b
12
35
AR
.
.
== =
343351
.
<
.
:
aspect ratioofshear
wall OK if blocked
.
R
L
5000
235
v
=
=
=
714
plfshear wall uni
ttshear
∑
SW
(.)
SW
The shear wall will be designed for ASD. Therefore the nominal unit shear capaci-
ties listed in SDPWS Table 4.3A will be divided by 2. Use two layers of 15/32″ sheathing
with 8d @ 6″ o.c.
2 730
2
(
)
v
==
v
w
=
730
plf
>
714
∴
OK
.
allow
Usually, at this stage, the design would have been considered to be complete and
the results would have been detailed on the drawings.
Case 2, check seismic loads that are slightly less than wind loads:
Aspect ratio = 3.43 : 1. In accordance with footnote 1 of Table 4.3.4, (Fig. 9.9), the allowable
aspect ratio for seismic loading is 2 : 1, but may be increased to 3.5 : 1 if the allowable
shear capacity is reduced by
2
b
h
.
w
e
1
=
190
plf
w
==
190 50
2
()
R
=
4750
lb diaphragmreactionattgrid line1
2
R
4750
235
v
=
=
=
679
plfshear wall uni
ttshear
∑
SW
(.)
L
SW
2235
12
b
h
=
(.)
=
0 583
.
reduction in allowableshear capacity
The walls have been designed for 15/32″ each side with 8d @ 6″ o.c., assuming that
it had a shear capacity of 730 plf. The actual shear capacity for seismic loading is
2 520
2
(
)
(.
v
==
v
s
0 583
)
=
303
plf
<
679
∴
N.G.
allow
Use two layers of 15/32″ sheathing with 8d @ 2″ o.c. and 3× framing, which has a
capacity of 1280 × 0.583 = 746 plf.
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