疲劳荷载作用下钢-混组合梁界面滑移对其性能影响研究

Influence of Interface Slip Effect on Fatigue Performance of Steel-Concrete Composite Girder Under Fatigue Loads

为分析界面滑移对钢-混组合梁疲劳性能的影响,在考虑界面滑移影响的栓钉疲劳刚度退化模型基础上,提出考虑界面滑移损伤的钢-混组合梁疲劳性能分析方法,以某工字钢-混组合连续梁为背景开展缩尺模型试验,建立考虑界面滑移损伤的钢-混组合梁疲劳性能分析模型梁,对比分析疲劳加载过程中试验梁与模型梁的疲劳性能,并进行界面滑移系数影响因素的参数分析。结果表明:疲劳荷载作用下,钢-混组合梁中钢梁下翼缘发生开裂,并最终导致组合梁失效,加载过程中钢-混组合梁跨中挠度及界面残余滑移均呈现明显的三阶段特征;模型梁跨中挠度及界面残余滑移随加载次数的变化趋势分析结果与试验梁吻合良好,验证了考虑界面滑移损伤的钢-混组合梁疲劳性能分析方法的可行性;疲劳荷载作用下钢-混组合梁界面滑移将引起钢梁中应力增加,从而降低组合梁疲劳寿命,建议在疲劳寿命预测中引入界面滑移疲劳折减系数,建议其取值为1.2。

This study focuses on the relationship between interface slip behaviors and fatigue performance of the steel-concrete composite girder.Based on the numerical modelling of the fatigue stiffness degradation of shear studs considering the interface slip effect,the method to analyze the fatigue performance of the steel-concrete composite girder considering interface damages is proposed.An existing continuous girder bridge with superstructure consisting of steel I girders and concrete slabs is used as a case.Scale-down mockup was prepared for the fatigue tests,and the fatigue behaviors of the steel-concrete composite girder was numerically modelled considering the interface damages associated with interface slip.The fatigue behaviors of the mockup and numerical model during loading process were compared,and the parametric analysis of influential factors of the interface slip coefficient was conducted.According to the tests and numerical modelling,the lower flanges of the steel I girder cracked during fatigue loading,which eventually resulted in the failure of the steel-concrete composite girder.The midspan bending and interface residual slip of the steel-concrete composite girder exhibited distinct three-stage feature during the loading process.The simulated variation of the midspan bending and interface residual slip along with fatigue cycles was in good agreement with the test results,which verified the applicability of the presented method to analyze the fatigue performance of the steel-concrete composite girder considering interface slip.Interface slip in the steel-concrete composite girder under fatigue loads will cause stress increase in the steel girder,thereby reducing the fatigue life of the overall composite girder.It is recommended to introduce interface slip fatigue reduction coefficient in the fatigue life prediction,and a value of 1.2 is suggested.