既有钢筋混凝土旧桥受力性能的破坏性试验研究

EXPERIMENTAL STUDY OF ULTIMATE BEHAVIOR OF EXISTING BRIDGE USING DESTRUCTIVE TESTING

  • 摘要: 服役多年实桥的真实承载能力和极限状态下的力学行为一直是研究人员关心的问题,但由于实桥破坏性试验实施困难,这方面的研究进展有限。该文对湖南省宁乡县一座服役43年的钢筋混凝土简支T梁桥实施了破坏性试验,考察了试验桥梁的全过程受力性能以及极限状态下的结构反应。首先对试验桥梁的材料强度、结构损伤及退化等进行了详细调查,试验中采用2个5000kN千斤顶对桥梁进行加载直至结构破坏,在此基础上进行有限元分析并与试验结果进行比较。试验结果表明:由于整体连接、边界条件、初始损伤等因素影响,试验实桥的受力性能表现出了结构模型与有限元分析不具有的局部非线性,但考虑了材料退化的有限元分析结果与试验结果呈现一定程度吻合;试验桥破坏形式为受拉钢筋屈服然后混凝土压碎的典型受弯结构破坏,除顶部混凝土压碎外桥梁支座等部位也出现了破坏迹象,表明实桥的破坏形式可能由多个因素控制。

     

    Abstract: The actual loading-carrying capacity and the behavior during an ultra state have always been concerned by researchers. However, there is little progress in this orientation due to the difficulty in actual bridge destructive tests. This paper carried out a destructive test of a forty-three-year-old reinforced concrete simply-supported T-beam bridge in Ningxiang County, Hunan province, to investigate the mechanical performance of the bridge during the whole process to destruction and structural reaction in a limit state. Based on the detailed pre-investigation of the material strength, the structure damage and degradation before the experiment, two 5000 kN jacks were employed to load the bridge to failure, and the finite element analysis was carried out to be compared with the experiment results. The test results showed that the tested bridge exhibit non-linear behavior in some stages which does not occur in structure models and finite elements analyses, affected by the factors due to the traverse connection, boundary conditions and initial damage; but the results of the finite element analysis still matched that of the experiment in some degree if the materials degradation was taken into consideration. A typical failure mode for bending structure was observed, which was caused by yielding of reinforcing bar and crushing of concrete; however, besides the crushing of upper concrete, the bridge bearing was also damaged, which indicates that the destruction form of the tested bridge maybe controlled by multiple factors.

     

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