酸雨腐蚀RC梁柱节点抗震性能及恢复力模型研究

Seismic Behavior and Restoring Force Model of RC Beam-Column Joints Affected by Acid Rain Corrosion

出于酸雨环境下钢筋混凝土(RC)结构抗震能力评估的需要,采用人工气候环境法对7榀RC梁柱节点组合体试件进行酸雨腐蚀试验,而后进行低周往复加载试验,分析腐蚀程度和轴压比对节点组合体破坏特征与滞回性能的影响.基于试验结果,分别采用试验拟合法及理论与回归相结合方法(以下简称为“理论回归法”),建立两种考虑腐蚀与轴压比影响的RC梁柱节点四折线骨架曲线模型,并分析其误差.同时,提出适用于腐蚀RC梁柱节点的滞回规则,该规则考虑循环退化效应与捏缩效应.在此基础上,建立酸雨腐蚀RC梁柱节点恢复力模型,并验证其有效性.结果表明:混凝土内部钢筋未锈蚀时,腐蚀试件抗震能力略有增强;内部钢筋锈蚀时,随着腐蚀程度的增大,试件抗震能力逐渐退化;具有较大轴压比的试件,其核心区斜裂缝出现时间偏晚且发展速率缓慢,而承载力相对较大,但延性较差;计算滞回曲线与试验滞回曲线吻合程度较高,骨架曲线与滞回耗能误差总体分别在10%和15%以内,良好的一致性说明该恢复力模型能够较好地表征腐蚀RC梁柱节点抗震性能.

To meet the need for the seismic behavior evaluation of reinforced concrete(RC)structures under acid rain environment,acid rain corrosion tests were conducted on seven RC beam-column joint specimens by using the artificial climate environment method.Qausi-static tests were then performed,and the influence of the corrosion degree and the axial compression ratio on the failure characteristics and hysteretic behavior of the specimens was analyzed.Based on the test results,two kinds of four-fold line skeleton curve models of RC beam-column joints were established by using the experimental fitting method and the combination of theory and regression method,which is hereinafter referred to as the“theoretical regression method”.The skeleton curve models considered the effects of the corrosion and the axial compression ratio,and their errors were analyzed.At the same time,a hysteretic rule suitable for the corroded RC beam-column joints,which considered cyclic degradation and pinch,was proposed.On this basis,the restoring force model of the RC beam-column joints corroded by acid rain was established and the accuracy was verified.The results show that,the seismic behavior of the corrosion specimen is slightly enhanced when the internal reinforcement is not corroded.In constrast,the seismic behavior of the specimen gradually deteriorates as the corrosion degree increases.For the specimen with a larger axial compression ratio,oblique cracks later appeared and slowly developed.The bearing capacity became relatively large,while the ductility worsened.The calculated hyster-etic curve was consistent with the experimental hysteretic curve.The error of the skeleton curve and the energy dissi-pation were within 10% and 15%,respectively.The good consistency shows that the restoring force model can de-scribe the seismic behavior of corroded RC beam-column joints.