Beer & Johnston — Pure Bending: Problem 4.48

4.48 Solve Prob. 4.47, assuming that the spacing of the 5/8–in.-diameter steel rods is increased to 7.5 in. (Reference Prob. 4.47: A concrete slab is reinforced by 5/8–in.-diameter steel rods placed on 5.5-in. centers as shown. The modulus of elasticity is \(3 \times 10^6\) psi for the concrete and \(29 \times 10^6\) psi for the steel. Using an allowable stress of 1400 psi for the concrete and 20 ksi for the steel, determine the largest bending moment in a portion of slab 1 ft wide.)