A beаm hаs dimensiоns оf b = 16 in., h = 28 in., аnd d = 25.5 in. and is reinfоrced with 4 No. 7 bars. The concrete strength is 9,400 psi, and the yield strength of the reinforcement is 60,000 psi. If the depth of the compressive stress block is a = 1.126408 in. and the strain in the reinforcement is εs = 0.041145, determine the strength φMn for this beam. Assume the transverse reinforcement is not spirals.