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Per ACI 318 standards (Section 25.4.2.1 in 2014 edition) and the homework, when calculating the development length of deformed bars, what is the minimum value of ld?

Determine the bar-spacing factor, cb, for a simply supported rectangular beam with b = 18 in. and No. 4 stirrups. This beam has three No. 7 bars as longitudinal reinforcement. The clear cover is 2 in.

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Determine the casting-position modification factor, ψt, for a rectangular beam with b = 16 in. and d = 20 in., five galvanized No. 7 Grade 60 tension-reinforcement bars placed in the top of the beam, and No. 3 Grade 60 stirrups located every 12 in. along the span. Assume 4,000-psi normal-weight concrete and a clear cover of 1.5 in.

Heat-of-hydration cracking can be prevented by proper mix design and by preventing rapid drying of the surface during the first hour or so after placing.

If φVc = 50 kip and Vu = 58 kip, are stirrups required?

Use ACI 318-14 Table 25.4.2.2 to determine the development length for the straight tension bars (no hooks) in a rectangular beam with b = 18 in. and d = 24 in., five galvanized No. 9 Grade 60 bars placed in the top of the beam, and No. 3 Grade 60 stirrups located every 6 in. along the span. Assume 5,000-psi lightweight concrete and a clear cover of 1.5 in.

A rectangular beam has a cross section of b = 18 in., h = 24 in., and d = 21.5 in. It is reinforced with five No. 5 Grade 60 bars. The concrete strength is 6,400 psi (normal weight). The beam has Grade 60 No. 3 stirrups satisfying ACI 318-14 Sections 9.7.6.2.2 and 9.6.3.3. Determine the strength φMn for this beam.

For a beam with stirrup hooks, the free end of the bar must extend at least _____ from the hook. Assume b1 = 35 in., b2 = 11 in., d1 = 6 in., d2 = 25 in., and that there are three No. 7 longitudinal tension bars and No. 3 stirrups at 6 in. o.c. The stirrup hooks are 90°.