When large amounts of steel are to be used, they can be bundled together. This decreases the required development length of each bar.

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 = 17 in. and d = 23 in., four galvanized No. 8 Grade 60 bars placed in the bottom of the beam, and No. 3 Grade 60 stirrups located every 10 in. along the span. Assume 8,000-psi lightweight concrete and a clear cover of 1.75 in.

Bond stresses must be absent whenever the stress or force in a reinforcing bar changes from point to point along the length of the bar.

Determine the size modification factor, ψs, for a rectangular beam with b = 18 in. and d = 23 in., three uncoated No. 7 Grade 60 tension-reinforcement bars placed in the top of the beam, and No. 3 Grade 40 stirrups located every 8 in. along the span. Assume 4,000-psi normal-weight concrete and a clear cover of 1.75 in.

When large amounts of steel are to be used, they can be bundled together. This increases the effective perimeter of each bar.

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. 8 bars as longitudinal reinforcement. The clear cover is 1.5 in.

Determine the transverse reinforcement index, Ktr, for a rectangular beam with b = 17 in. and d = 20 in., three epoxy-coated No. 6 Grade 60 tension-reinforcement bars placed in the bottom of the beam, and No. 3 Grade 40 stirrups located every 12 in. along the span. Assume 8,000-psi normal-weight concrete and a clear cover of 1.5 in.

Determine the casting-position modification factor, ψt, for a rectangular beam with b = 17 in. and d = 21 in., five galvanized No. 7 Grade 60 tension-reinforcement bars placed in the bottom of the beam, and No. 3 Grade 40 stirrups located every 8 in. along the span. Assume 7,000-psi lightweight concrete and a clear cover of 1.75 in.

Development lengths are the same for compression and tension.

A rectangular beam has a cross section of b = 16 in., h = 22 in., and d = 19.5 in. It is reinforced with three No. 6 Grade 60 bars. The concrete strength is 3,700 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.