疲劳荷载后重载铁路桥梁剩余静载承载力试验研究

发布时间：2018-08-16 10:18

【摘要】：基于应变和振幅的疲劳试验实时测试系统,通过10片1/6缩尺模型梁疲劳试验,研究重载铁路桥梁疲劳后静载破坏形态以及振幅、刚度、非预应力筋和预应力筋应变、混凝土应变随反复荷载次数的变化规律。研究表明:重载铁路32m预应力混凝土梁疲劳后剩余静载承载力演变呈现"Z"字形三折线的3个阶段,即基本不变阶段、直线下降阶段和压弯失稳破坏阶段。第一阶段,疲劳后试件静载破坏形态与普通静载破坏形态相同,试件静载承载力基本保持不变;第二阶段,试件静载承载力直线下降,直至压弯失稳破坏,最终梁的剩余静载承载力降至原有承载力的50%~60%,主要由预应力筋提供。与普通静载破坏试验相比,疲劳后静载破坏试验不同的地方主要表现在混凝土、梁底普通钢筋和预应力筋等材料的应力-应变本构关系上,受压区混凝土残余应变不断增加,变形模量降低了20%~30%,普通钢筋和预应力筋残余应变也明显增加,但弹性模量和屈服强度(预应力筋极限强度)基本不变。
[Abstract]:A real time fatigue test system based on strain and amplitude is used to study the failure modes of static load, amplitude, stiffness, non-prestressing tendons and prestressed tendons strain of heavy-haul railway bridges after fatigue, through the fatigue tests of 10 1 / 6 scale model beams. The variation of concrete strain with the number of repeated loads. The results show that the evolution of residual static load bearing capacity of 32m prestressed concrete beams of heavy haul railway shows three stages of "Z" zigzag triple-fold line, namely, the stage of basic invariance, the stage of straight line descending and the stage of buckling and failure of compression and bending. In the first stage, the failure mode of static load of the specimen after fatigue is the same as that of the normal static load, and the static load bearing capacity of the specimen remains basically unchanged; in the second stage, the static load bearing capacity of the specimen decreases linearly until the buckling failure occurs. The residual static load capacity of the ultimate beam is reduced to 50% of the original bearing capacity, which is mainly provided by prestressed tendons. Compared with the normal static load failure test, the main stress-strain constitutive relationship of concrete, common steel bar and prestressed tendons at the bottom of beam is the stress-strain constitutive relation of concrete, and the residual strain of concrete in compression zone is increasing continuously. The deformation modulus is reduced by 20%, and the residual strain of common steel bar and prestressed reinforcement is increased obviously, but the elastic modulus and yield strength (ultimate strength of prestressed tendons) are basically unchanged.
【作者单位】：中南大学土木工程学院;高速铁路建造技术国家工程实验室;
【基金】：国家863高技术研究发展计划(2009AA11Z101)
【分类号】：U446;U448.13

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