关键词: 预应力FRP筋, 组合梁, 轴向力, 计算公式

Abstract: The relative slip will unavoidably come to pass on the bar-concrete interface in a prestressed FRP bar-concrete composite beam under external loading, and the stress in a prestressed FRP bar increases correspondingly with the external loading. The interface slip and stress increment will result in the stress redistribution between concrete flange plate, and H-steel beam and shear connector. According to the structural and bearing characteristics and elastic theory, some differential equations of axial force on which the effects of both interface slip and stress increment are taken into account are given, as well as the formulae of the axial force acting on both the concrete slab and H-steel beam under uniformly distributed load. The results of calculation showed that the axial force to the composite beam increases with the increasing connection stiffness and external load, and the maximum axial force is found at the midspan, then it decreases gradually from midspan to beam end where it is approximately zero. As to the effect of stress increment in prestressed FRP bars on the axial force to composite beam, it is so small that it can be ignored.