Determine the lightweight modification factor, λ, for a rectangular beam with b = 16 in. and d = 21 in., four galvanized No. 9 Grade 60 tension-reinforcement bars placed in the bottom of the beam, and No. 4 Grade 60 stirrups located every 8 in. along the span. Assume 6,000-psi normal-weight concrete and a clear cover of 2 in.

A rectangular beam with cross section b = 16 in., h = 22 in., and d = 19.5 in. supports a total factored uniform load of 3.00 kips/ft, including its own dead load. The beam is simply supported with a 20-ft span. It is reinforced with five No. 7 Grade 60 bars, three of which are cutoff between midspan and the support and two of which extend 10 in. past the centers of the supports. The concrete strength is 7,500 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. The strength of the five bars is φMn = 251.3 kip-ft, and the strength of the remaining two bars is φMn = 103.4 kip-ft. Determine the distance from the support to the theoretical cutoff point (i.e. disregard ACI 318-14 Section 9.7.3.3).

A rectangular beam with cross section b = 14 in., h = 24 in., and d = 21.5 in. supports a total factored uniform load of 2.70 kips/ft, including its own dead load. The beam is simply supported with a 24-ft span. It is reinforced with five No. 8 Grade 60 bars, three of which are cutoff between midspan and the support and two of which extend 10 in. past the centers of the supports. The concrete strength is 6,300 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. The strength of the five bars is φMn = 354.1 kip-ft, and the strength of the remaining two bars is φMn = 148.4 kip-ft. Determine the distance from the support to the theoretical cutoff point (i.e. disregard ACI 318-14 Section 9.7.3.3).

Inclined stirrups are an effective solution for resisting seismic loads.

Smooth bars are generally not used as longitudinal reinforcement because _______.

Determine the bar-spacing factor, cb, for a simply supported rectangular beam with b = 16 in. and No. 3 stirrups. This beam has four No. 7 bars as longitudinal reinforcement. The clear cover is 2 in.

A rectangular beam with cross section b = 16 in., h = 28 in., and d = 25.5 in. supports a total factored uniform load of 3.60 kips/ft, including its own dead load. The beam is simply supported with a 22-ft span. It is reinforced with four No. 8 Grade 60 bars, two of which are cutoff between midspan and the support and two of which extend 10 in. past the centers of the supports. The concrete strength is 4,500 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. The strength of the four bars is φMn = 340.6 kip-ft, and the strength of the remaining two bars is φMn = 175.8 kip-ft. If the distance from the support to the theoretical cutoff point is 6.170 ft, determine the distance from the support to the actual cutoff point (i.e. use ACI 318-14 Section 9.7.3.3).

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Development length is the shortest length of bar in which the bar stress can increase from zero to the yield strength.

The development length is different in tension and compression, because a bar loaded in tension is subjected to in-and-out stresses.