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Solution:
(1) Dynamic strength of materials from Table 53 0oe NAVFAC
P397 for intermediate and low pressure range.
Reinforcing steel  bending, DIF = 1.10
Concrete  compression, DIF
=
1.25
 direct shear, DIF
=
1.10
Using Equations (32) and (33):
Reinforcing steel  bending fdy = 1.1 x 60,000
= 66,000 psi
Concrete  compression f'dc
= 1.25 x 4,000
= 5,000 psi
 direct shear f'dc = 1.10 x 4,000
= 4,400 psi
(2) Assume 5 No. 6 bars for bending:
As = 5 x .44
= 2.20 in2
For concrete cover and beam sections see Figure 38b.
(3)
Calculate d negative (support) and positive (midspan)
for checking bending reinforcement ratios.
[phi]
d = h  d' (cover)  [phi]'(tie)  (Bending Bar)
2
dN = 30  2  0.5  0.75/2
= 27.125 in
dp = 30  1.5  0.5  0.75/2
= 27.625 in
From Equation (36);
p = As/bd
PN = 2.2/(18 x 27.125)
= 0.0045
Pp = 2.2/(18 x 27.615)
= 0.0044
Maximum reinforcing ratio pmax = 0.75 x P'b
2.08108


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