For the trapezoidal singly-reinforced (reinforeement in tension only) concrete section shown below, we want to determine the of the ultimate limit state of the beam. The properties of the materials are f=4500 psi for the concrete and f, =60 ksi for the reinforcement. 14 in. 21 in. 18 in. 3- #7 bars 10 in. a) Draw the complete diagrams showing strain, stress, and equivalent forces acting along the depth of the cross-section. In the equivalent force diagram, clearly indicate both the magnitude of the force and its point of application using symbols. b) What is the moment capacity/strength (M = M,) and curvature ( = W,) just at ultimate? Utilize Whitney's stress block for the concrete and elasto-plastic behavior for steel.