高铁站房型钢混凝土梁疲劳性能试验

Experiment Study on Fatigue Behavior of Steel Reinforced Concrete Girders at High-speed Railway Stations

鉴于型钢混凝土(SRC)梁在高铁站房应用的需要,对3根尺度和构造细节与实际工程一致的H型钢混凝土梁进行了基于设计荷载的静力试验和200万次的疲劳试验.在此基础上,继续进行了增大荷载幅的疲劳试验.介绍了SRC梁试件、加载和测试等方案以及试验结果,比较了静力加载和疲劳加载阶段的结构性能,阐述了SRC梁疲劳裂纹萌生和扩展的破坏特点.研究表明:在设计荷载静力作用和200万次循环作用下,SRC梁保持完好,处在弹性阶段,混凝土表面最大裂缝宽度不超过0.2mm;增大荷载幅之后,这些SRC梁又经历了31～146万次寿命后发生疲劳破坏;疲劳破坏之前,SRC梁各组件协同工作良好,应变分布符合平截面假定;疲劳破坏起源于H型钢受拉翼缘与腹板的焊接部位,焊接H型钢梁的疲劳性能对整个SRC梁的疲劳强度起着十分关键的作用.最后提出了改善SRC梁疲劳强度的建议和未来需进一步研究的工作.

For the sake of the application of steel reinforced concrete （SRC） girders to high speed railway stations, the static and 2 million-cycle fatigue tests were carried out on three H-section steel reinforced concrete girders with the same dimension and constructional detail as those of an engineering project under the designed loading.Subsequently, some further fatigue tests were carried out under the higher loadings, and the specimens, loading and testing program as well as the experiment results were preseated accordingly. A comparative study was also made of structural behavior under static and fatigue loading. The failure feature of SRC girders about fatigue crack initiation and propagation was described. Experiment study results show that the SRC girders remains in good condition and at the stage of elasticity when they are tested with the designed static loading and 2 million-cycle fatigue loading. The concrete surface crack develops within 0. 2 mm. Fatigue failure occurs when higher loadings and another 0.31 to 1.46 million cycles being applied to the girders. Before the fatigue failure, all components of the SRC girders collaborate well and their strain distribution agree well with the assumption of plane cross section. The fatigue failure initiates from the welded connection between a flange and a web of the Hsection steel. The fatigue behavior of the welded H-section steel beam plays a key role in the fatigue strength of SRC girders. The proposals for improving the fatigue strength of SRC girders and future research works are put forword finally.