组合梁在负弯矩作用下的刚度分析

为探讨组合梁在负弯矩作用下钢梁与混凝土板之间的滑移效应以及混凝土与纵向钢筋之间的粘结滑移对截面刚度的影响,建立了考虑以上两种滑移效应的组合梁受力模型,并结合试验进行了理论推导和对比分析。结果表明,即便按照完全剪力连接设计的组合梁,滑移效应仍在一定程度上产生了附加曲率,使组合梁的截面刚度比按照换算截面法得到的刚度降低(10%~20%左右),在设计时不可忽略。本文同时推导了计算悬臂组合梁挠度的公式,并为有关连续组合梁刚度的进一步试验研究提供了依据。

ANALYSIS OF COMPOSITE BEAM STIFFNESS UNDER NEGATIVE BENDING

Slip occurs both at joist-slab interface and concrete-reinforcement interface of composite steel-concrete beams under negative bending moment. In this paper, a mechanical model is established to investigate the stiffness of composite beams considering two types of slip. In order to validate the model, a test of 3 full-scale specimen beams was conducted. The results show that slip always exists for composite beams under negative bending even with complete shear interaction between the steel and concrete components. The slip effect makes additional curvature of the beam and reduces the section stiffness by 10% to 20% in comparison with that given by transformed section method. Hence, the slip effect cannot be neglected in design. Formulae are also proposed to calculate the deflection of cantilever beams. The results can serve as a basis for further study on stiffness of continuous composite steel-concrete beams.