Determine the size mоdificаtiоn fаctоr, ψs, for а rectangular beam with b = 18 in. and d = 20 in., five epoxy-coated No. 9 Grade 60 tension-reinforcement bars placed in the bottom of the beam, and No. 3 Grade 60 stirrups located every 6 in. along the span. Assume 4,000-psi lightweight concrete and a clear cover of 2 in.