考虑氯离子侵蚀下的RC桥墩时变抗震韧性分析

Time-dependent seismic resilience analysis of RC bridge piers considering chloride induced erosion

为研究氯离子侵蚀对钢筋混凝土(RC)桥墩抗震韧性的影响,对服役于海洋潮汐环境中不同服役时间的桥墩进行抗震韧性分析.首先,对遭受不同时间氯离子侵蚀的RC桥墩钢筋进行强度和直径的折减;然后,结合Pushover分析结果确定不同破坏状态的损伤界限值,再运用增量动力分析(IDA)方法计算地震易损性;最后,基于地震易损性,同时考虑桥墩自身功能的退化及震后的修复,利用破坏概率对传统修复函数的韧性结果进行修正,提出了一种改进的韧性评估方法,对桥墩进行抗震韧性评估.结果表明:改进的抗震韧性评估结果与构件失效概率的趋势一致且属于合理范围之内,该方法克服了传统三种修复函数使用范围的局限性;随着服役时间的增加,当遭遇0.3g地震作用时服役40 a和50 a桥墩的抗震韧性退化幅度分别达到25.68%和35.64%,表明氯离子侵蚀对桥墩的抗震韧性有着显著影响,为桥墩抗震设计或者加固提供一定的参考依据.

In order to study the influence of chloride ion induced erosion on the seismic resilience of reinforced concrete(RC)bridge piers,the seismic resilience analysis of bridge piers with different service years in the marine environment was carried out.First,the strength and diameter of the RC bridge pier steel bars subjected to chloride ion induced erosion at different times were reduced.And damage limits for different failure states were determined based on the results of Push over analysis,and the seismic fragility was calculated by the incremental dynamic analysis(IDA)method.Based on the seismic fragility,considering functional own loss and post-earthquake repair,an improved toughness evaluation method was proposed by modifying the toughness results of traditional repair functions using failure probability to evaluate the seismic resilience of bridge piers.The results show that the evaluate result of improved seismic resilience is consistent with the trend of the failure probability of the components within a reasonable range.At the same time,the method overcomes the limitations of the use scope of the three traditional repair functions,which indicates that the method has certain applicability.With the increase of service time,when subjected to 0.3g earthquake,the seismic resilience degradation of bridge piers serving for 40 a and 50 a reaches 25.68%and 35.64%respectively.It shows that chloride ion induced erosion has a significant impact on the seismic resilience of bridge piers,and provides a certain reference basis for the seismic design or reinforcement of bridge piers.