A rectangular beam having b  = 10 in. and d  = 17.5 in. spans 15 ft face to face of simple supports. It is reinforced for flexure with three No. 9 (No.29) bars that continue uninterrupted to the ends of the span. It is to carry service dead load D  = 1.27 kips/ft (including self-weight) and service live load L =  3.70 kips/ft, both uniformly distributed along the span. Design the shear reinforcement, using No. 3 (No. 10) vertical U stirrups. The more approximate Eq. (4.12 b  ) for Vc  may be used. Material strengths are f′c  = 4000 psi and fy =  60,000 psi.