考虑多组件疲劳损伤的组合梁剩余承载力计算方法及试验验证

针对现行规范中无法计算钢-混凝土组合梁在疲劳后的剩余承载力问题,提出考虑多组件疲劳损伤的组合梁剩余承载力的计算方法。基于材料剩余强度理论,分别引入组合梁各组件(混凝土板、钢梁和栓钉连接件)在疲劳荷载作用下的强度衰减模型;对疲劳荷载作用下的组合梁进行受力分析,得到在既定疲劳荷载幅值下各组件的疲劳应力幅;将各组件的疲劳损伤计入钢-混凝土组合梁剩余抗弯承载力计算中,并考虑疲劳加载过程中组合梁抗剪连接度的变化,建立完全抗剪连接和部分抗剪连接两种情形下的组合梁剩余承载力计算方法,并通过6个试验梁的剩余承载力试验进行验证。研究结果表明:在疲劳荷载作用下,组合梁的抗剪连接度逐渐降低,剩余承载力退化明显且不可忽略。该文建立的组合梁剩余承载力计算方法的计算值与试验值吻合较好,具有良好的计算精度与适用性,补充并完善了现有组合梁承载力的计算方法。

CALCULATION METHOD AND EXPERIMENTAL VERIFICATION OF THE RESIDUAL STRENGTH OF COMPOSITE BEAMS CONSIDERING THE FATIGUE DAMAGE OF MULTI-COMPONENTS

In view of the problem that the residual strength of steel-concrete composite beams after fatigue cannot be calculated in the current codes, a method for calculating the residual strength of composite beams considering multi-component fatigue damage is proposed. Based on the material residual strength theory, the component strength attenuation models of the concrete slab, steel beam and stud connector in a composite beam under fatigue load were introduced. The fatigue stress amplitude of each component under the given fatigue load was then obtained by the stress analysis of the composite beam under fatigue load. The fatigue damage of each component was included in the calculation of the residual strength of steel-concrete composite beams. Considering the change of the shear connection degree of composite beams during fatigue loading, the calculation methods of the residual strength of composite beams under complete and partial shear connections were established and verified through the test of the residual strength of six beams. The results show that the shear connection degree of composite beams decreases gradually under fatigue load, and that the residual strength degradation is obvious and cannot be neglected. The calculation results of the residual strength of composite beams by the method established in this paper are in good agreement with the experimental values. The method has good calculation accuracy and applicability. It complements and improves the existing calculation methods of composite beams.