冲击后剩余承载性能是评估结构抗冲击性能的重要指标。为研究钢筋混凝土(Reinforced Concrete, RC)梁冲击后剩余承载力及损伤后承载机制，对12片简支RC梁进行了落锤冲击以及冲击后静力加载试验，基于显式动力有限元分析方法对冲击及其冲击后静载全过程进行了仿真模拟，探讨了冲击能量和构件参数（拉筋率、压筋率、箍筋率和混凝土强度）对RC梁冲击后剩余承载性能的影响，基于试验和数值模拟数据得到了损伤后RC梁剩余承载力的预测公式，分析了影响冲击损伤RC梁剩余承载力的本质原因。研究结果表明：RC梁冲击接触局部区域混凝土破损，跨中区域产生较为严重的垂直裂缝和斜裂缝；随着冲击能量的增大，梁的冲击损伤更为严重。不同冲击参数下RC梁的承载力发生不同程度的下降，受压钢筋和箍筋配筋率的增加降低了承载力退化程度，而增加受拉钢筋配筋率虽然可以提高RC梁原始承载力，但其冲击后承载力下降比例也越大，混凝土强度下对于受冲击损伤的RC梁残余性能没有显著的影响。冲击后RC梁承载力下降与否与其在极限状态的破坏控制模式相关。
Abstract
The residual performance after impact loading is a key index to evaluation the anti-impact ability of structures. In order to investigate the residual resistance of reinforced concrete(RC)beam and the post-impact bearing mechanism. The drop hammer impact tests, as well as the static loading tests after impact, are conducted on 12 simply supported RC beams. High-resolution explicit dynamic finite element approach is adopted to get the impact and post-impact static loading responses. The effects of impact energy, as well as the structural parameters (i.e., tensile reinforcement ratio, compressive reinforcement ratio, stirrups ratio and concrete strength) on residual bearing performance of RC beam are discussed. The formula for predicting the residual resistance of impact-damaged RC beam is regressed according to the experimental and numerical simulation data. The essential reasons affecting the residual bearing capacity of impact-damaged RC beams are analyzed finally. The experimental and numerical results show that severe concrete spalling occurs at the contact zone impacted by drop hammer. Significant vertical and oblique cracks can be observed at the mid-span. Higher impact energy causes more severe impact damage of RC beam. The ultimate bearing capacity of RC beam under various impact cases decrease at a certain extent. The increased ratios of compressive reinforcement and stirrups alleviate the deterioration of bearing capacity. Larger reduction percentage on the resistance of impact-damaged RC beam is yielded by the case with larger tensile reinforcement ratios, though it has larger flexural resistance. No obvious difference can be found on the residual performance of RC beams under various concrete strengths, which demonstrates that the residual resistance is not affected by the concrete strength. Whether the bearing capacity of RC beam decreases after impact depends on its failure pattern at ultimate stage.
关键词
钢筋混凝土梁 /
落锤试验 /
剩余承载性能 /
预测模型 /
承载机制
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Key words
reinforced concrete beam /
drop hammer impact test /
residual bearing performance /
prediction model /
bearing mechanism
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