Civil Engineering Reference
In-Depth Information
Figure 20.5
Deflection:
1
360
Permissible deflection
(12
2)
0.067
12
)(12
2)
4
(128)(1.43
(
225
4
128
EI
w
Actual
10
6
)(0.198)
0.172
0.067
No good
Joists
Properties of 2
6 joist with finished dimensions
1
2
5
2
:
A
8.250 in.
2
,
I
20.80 in.
4
,
S
7.56 in.
3
Load per foot
(2)(225)
450 lb/ft
Bending and shear stresses:
10
(450)(4)
2
M
w
2
720 ft- lb
10
f
b
(12)(720)
7.56
1143 psi
1875 psi
OK
2
12
4
2
5.50
12
V
0.6
w
(0.6)(450)
832.5 lb
2
A
(3)(832.5)
f
v
3
V
(2)(8.25)
151 psi
180 psi
OK
Deflection:
1
360
Permissible deflection
(12
4)
0.133
12
)(12
4)
4
(128)(1.76
10
6
)(20.80)
0.0425
0.133
(
450
4
128
EI
w
Actual
OK
