sm7 63

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PROBLEM (*7.63) A beam with two overhang carries a uniform load of intensity w and
supported as shown in Fig. P7.63. Determine the maximum permissible value of the load w.
Given: Allowable tensile and compressive stresses of 6 and 10 ksi, respectively, and a shearing
stress not to exceed 1.2 ksi
*SOLUTION
Let w be in .inlb
From solution of Prob. 7.31:
y
4
.63.13 inI =
.451275.3
max inlbwwV ⋅=
×
=
We have
3
648 (2.237) 610
13.63
tMc w
I
σ == =×
or
.4.56 inlbw
=
3
684 (1.763) 10 10
13.63
cMc w
I
σ == =×
or
.119 inlbw =
3
max max
max 45 [1(2.237)(2.237 2) 1.2 10
13.63(1)
VQ w
Ib
τ == =×
or
.145 inlbw =
Thus,
.4.56 inlbwall =
1 in. 1. 1 in. 5 in.
z
763 1.
2. 237
C
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