Q1: If the loading on a prestressed rectangular beam, is uniformly distributed, the tendon to be provided should be .

ANS:B - parabolic with convexity downward

When a prestressed rectangular beam is subjected to uniformly distributed loading, the tendon profile is typically chosen to counteract the resulting bending moment and ensure the desired prestressing effect. In such cases, the tendon profile is often selected to be parabolic with convexity upward. This means that the tendon is positioned in a parabolic curve above the centroidal axis of the beam. The rationale behind this choice is to induce a compressive force in the lower portion of the beam (where tension would typically occur under the uniformly distributed load), thereby counteracting the tensile stresses induced by the loading. The upward convexity of the tendon ensures that the maximum prestressing force is applied to the lower portion of the beam where it is needed the most to counteract the bending moment. Therefore, the correct choice from the given options is: parabolic with convexity upward.