In With one-storey, two-span prestressed frames, a comparative study is done between under vertical and horizontal loads. The studies include the pattern of the plastic hinges occurring and, the demanded and available rotational capability of the hinges in critical sections. The relative height of compression zone and prestressed degree are considered. The result indicates that there is much difference in the pattern of the plastic hinge occurring when each plastic hinge has enough rotational capability. The beams can finish a full redistribution of internal force under vertical loads, but not under horizontal loads. Moreover, as increasing of the relative height of compression zone, a stronger rotational capability of hinges will be demanded to finish a full redistribution under vertical loads when a weaker rotational capacity will be needed under horizontal loads.