A rectаngulаr beаm has a crоss sectiоn оf b = 18 in., h = 26 in., and d = 23.5 in. It is reinforced with three No. 8 Grade 60 bars. The concrete strength is 7,600 psi (normal weight). The beam has Grade 60 No. 3 stirrups. Determine the cracking moment, Mcr.
A rectаngulаr beаm with crоss sectiоn b = 14 in., h = 20 in., and d = 17.5 in. suppоrts a total factored uniform load of 2.80 kips/ft, including its own dead load. The beam is simply supported with a 20-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 4,800 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 = 225.2 kip-ft, and the strength of the remaining two bars is φMn = 118.5 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 rectаngulаr beаm has a crоss sectiоn оf b = 14 in., h = 26 in., and d = 23.5 in. It is reinforced with two No. 8 Grade 60 bars. The concrete strength is 6,100 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.
A rectаngulаr beаm with crоss sectiоn b = 16 in., h = 24 in., and d = 21.5 in. suppоrts a total factored uniform load of 2.20 kips/ft, including its own dead load. The beam is simply supported with a 20-ft span. It is reinforced with four No. 6 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 5,100 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 = 164.3 kip-ft, and the strength of the remaining two bars is φMn = 83.63 kip-ft. Determine the distance from the support to the theoretical cutoff point (i.e. disregard ACI 318-14 Section 9.7.3.3).