A rectangular concrete beam has dimensions b=16 in. and h=30 in. The location of the Gr. 60 reinforcing bars, which are placed a
ll in one row in the bottom of the section, is d=27 in. Using a specified compressive strength of concrete of 5,000 psi and the assumptions and simplifications of the ACI 318-14 Code, find the nominal flexural strength Mn for positive bending if the reinforcing bars are: a. Three No. 9 bars b. Four No. 9 bars c. Three No. 8 + two No. 10 bars d. None (i.e., the beam is unreinforced)
1 answer:
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Answer:
a) 280MPa
b) -100MPa
c) -0.35
d) 380 MPa
Explanation:
GIVEN DATA:
mean stress
stress amplitude
a)
--------------1
-----------2
solving 1 and 2 equation we get
b)
c)
stress ratio
d)magnitude of stress range
= 280 -(-100) = 380 MPa