氯离子腐蚀环境下桥梁抗震性能分析

Seismic Performance Analysis of Bridges under Chloride Ion Corrosion

氯离子腐蚀是海洋地区混凝土结构劣化的主要原因,为此提出了既有锈蚀钢筋混凝土桥梁长期地震评价的新框架。主要步骤包括腐蚀起始时间的计算、考虑腐蚀影响的材料模型的建立、桥梁立柱弯矩曲率分析。腐蚀的影响主要包括覆盖层和核心混凝土的退化,通过对桥梁在使用寿命中某一特定时刻的抗震能力进行比较,确定了桥梁结构中仅纵筋腐蚀、仅箍筋腐蚀和纵箍筋一起腐蚀对桥梁长期抗震性能的影响。分析表明:桥梁结构一起考虑纵筋和箍筋的腐蚀情况下抗弯能力比仅考虑纵筋腐蚀或者箍筋腐蚀要小很多;并且桥梁结构考虑纵箍筋一起腐蚀的情况下,桥墩结构的滞回耗能能力降低幅度最为明显;随着使用寿命的增加,桥墩结构的抗弯能力和滞回耗能能力均表现下降趋向。

Chloride ion corrosion is the main reason for the deterioration of concrete structure in marine areas.This paper proposes a new framework for long-term seismic evaluation of corroded reinforced concrete bridges. The main steps include the calculation of the corrosion start time,the establishment of the material model considering the corrosion effect,and the bending moment curvature analysis of the bridge column. The effects of corrosion mainly include the degradation of the cover layer and core concrete. By comparing the seismic capacity of the bridge at a certain moment in its service life,it is determined that only the longitudinal reinforcement,only the stirrup corrosion and the longitudinal stirrup together in the bridge structure affect the long-term seismic performance of the bridge.The analysis shows that the bending resistance of the bridge structure considering the longitudinal reinforcement and the stirrup is much smaller than that considering only the longitudinal reinforcement or the stirrup corrosion;and the bridge structure considers the corrosion of the longitudinal stirrup together,the lag of the pier structure The reduction of energy consumption is the most obvious;with the increase of service life,the bending capacity and hysteretic energy consumption of the pier structure are declining.