集中荷载作用下宽翼缘双箱组合梁剪滞效应分析

宽翼缘钢-混凝土组合梁结构中剪滞效应的存在将导致混凝土翼板、钢梁底板及腹板发生纵向翘曲变形,对组合梁截面应力和变形产生重要影响。为了深入分析其作用机理,该文基于最小势能原理,忽略界面滑移效应,在假定混凝土翼板、钢梁底板纵向变形沿板宽度方向呈近似抛物线分布的前提下,推导了宽翼缘双箱钢-混凝土组合梁结构考虑剪滞效应的控制微分方程。并求得在两端简支约束条件和集中荷载作用下的应力和变形解析表达式。通过数值算例,结合组合梁试验、有限元模拟三者相互比较分析,表明该文提出的方法为分析组合梁结构关于剪滞效应问题提供了理论基础,对工程应用具有一定的指导作用和参考价值。

ANALYSIS OF SHEAR LAG EFFECT IN DOUBLE-BOX COMPOSITE BEAMS WITH WIDE FLANGES UNDER CONCENTRATED LOADING

The shear lag effect in steel-concrete composite beam structures with wide flanges leads to longitudinal buckling deformation of the concrete slab and the bottom and web plates of the steel girder, and has significant effect on stress and deflection in composite beams. In order to further analyze its mechanism, the governing differential equation of a double-box composite structure with wide flanges considering the shear lag effect is deduced, based on the minimum potential energy principle, and ignoring slip effects in the interface, under the assumption that longitudinal deformations of the concrete slab and steel girder bottom-plate follow an approximately parabolic distribution along their width. Then analytical expressions of stress and deformation are obtained for a beam with both ends simply supported, under concentrated loading. Finally, a comparative analysis between a numerical example, composite beam experiment, and finite element simulation is implemented, and the results show that the proposed approach provides a theorical basis for analyzing the shear lag effect in composite beam structures, and this method has a definite guidance and reference value for engineering applications.