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The basic strength requirement from ACI 318 is “Reduced nominal strength ​≤ Factored load effects.”

A simply supported beam with dimensions of b = 16 in., h = 22 in., d = 19.5 in., and L = 16 ft supports a uniform service (unfactored) dead load consisting of its own weight plus 1.7 kips/ft and a uniform service (unfactored) live load of 0.9 kips/ft. The concrete is normal-weight concrete. Determine the moment due to the factored loads, Mu.      

Because a slab is thinner than the beams supporting it, the concrete in the slab shrinks more slowly than the concrete in the beams.

In analysis, the objective is to select a suitable cross section, dimensions, concrete strength, etc. given a specific factored design moment. There are many possible solutions.

A beam has dimensions of b = 14 in., h = 26 in., d’ = 2.5 in., and d = 23.5 in. It is reinforced with 2 No. 5 bars on the compression side and 4 No. 8 bars on the tension side. The concrete strength is 3,100 psi, and the yield strength of the reinforcement is 60,000 psi. If the depth of the neutral axis is c = 5.205 in., determine the strain in the compression reinforcement, ε’s.

A beam has dimensions of b = 14 in., h = 30 in., and d = 27.5 in. and is reinforced with 5 No. 5 bars. The concrete strength is 6,100 psi, and the yield strength of the reinforcement is 60,000 psi. Determine the nominal moment capacity, Mn, of the beam.

The use of a layer of closely spaced bars will prevent splitting failures along the plane of the reinforcement.

A beam has dimensions of b = 16 in., h = 22 in., and d = 19.5 in. and is reinforced with 2 No. 5 bars. The concrete strength is 10,000 psi, and the yield strength of the reinforcement is 60,000 psi. Determine the strength Mn for this beam.

A beam has dimensions of b = 14 in., h = 28 in., and d = 25.5 in. and is reinforced with 2 No. 8 bars. The concrete strength is 5,200 psi, and the yield strength of the reinforcement is 60,000 psi. If the depth to the neutral surface is c = 1.939237 in., determine the strain in the reinforcement.

In a one-way slab, the slab strips used for analysis span the long direction of the panel.