滨海预制拼装RC桥梁的地震失效机理及其全寿命地震易损性分析

Segmental precast reinforced concrete (RC) bridge, which can both ensure construction quality and be accelerated bridge construction, has gradually attracts increasingly more attentions from bridge engineers. The splicing structure and seismic performance of segmental precast pier remain two open questions, especially life-cycle deterioration mechanism and the time-varying characteristics of seismic performance of Segmental precast RC bridge under coastal environment actions coupled with applied loadings. In this project, ①Physical quasi-static model tests and numerical simulations will be conducted to investigate the damage evolution process and failure mode of segmental precast RC bridge pier, and the seismic performance of segmental precast RC bridge pier is evaluated based on the findings from the model tests and numerical simulations ；②Physical model test and numerical simulation will be adopted to develop the key connection structure of segmental precast RC bridge pier, and to optimize the shear resistant measures of segmental precast RC bridge pier to improve its seismic performance. ③The effects of chloride ion erosion and the characteristics of rebar rust expansion together with concrete cracking under coastal environment actions and complex stress loading will be studied by means of theoretical analysis and physical test. The time-dependent model of mechanical behavior of reinforced concrete element will be established. ④Life-cycle seismic vulnerability curve of segmental precast RC bridge with Coastal Environmental will be studied. The life-cycle seismic performance analysis method of segmental precast RC bridge with Coastal Environmental based seismic vulnerability curve will be established. This project provides helpful theoretical foundation and technical support for seismic design of coastal segmental precast RC bridge. The research work has significant theorical and engineering value for earthquake risk reduction of coastal segmental precast RC bridge.

既能够保证构件质量又可以快速修建的预制拼装RC桥梁，已逐渐成为下一代桥梁工程的发展方向，预制拼装桥墩的拼接构造及抗震性能是其亟待研究的问题，尤其是滨海环境和荷载耦合作用下预制拼装RC桥梁的全寿命劣化规律、抗震性能演化时变特征的研究。本项目拟①采用模型拟静力试验和数值模拟方法，研究预制拼装RC桥墩的损伤演化过程和失效模式，进而全面评估预制拼装RC桥梁墩柱的抗震性能；②采用物理试验和数值模拟的方法，研发预制拼装RC桥墩关键连接构造，提高其抗震性能；③通过理论分析和物理试验方法，研究滨海环境和复杂应力荷载作用下氯离子侵蚀、钢筋锈胀、混凝土开裂特征，构建钢筋混凝土构件力学行为的时变模型；④研究滨海预制拼装RC桥梁的全寿命地震易损性曲线，建立基于地震易损性的滨海预制拼装RC桥梁的全寿命抗震性能分析方法。本项目为预制拼装RC桥梁抗震设计提供理论基础，具有重要的理论意义和工程价值。

预制拼装桥墩具有施工速度快、工程质量可控、环保、可工厂化生产等优点，但预制拼装桥墩抗震性能尤其是耗能能力成为制约其在地震区广泛应用的关键。同时海洋环境对于钢筋混凝土结构的侵蚀、劣化机理和发展进程都直接影响着在役桥梁的抗震性能。因此混凝土构件在海洋环境下材料劣化时变特性对桥梁抗震性能的影响研究尤为重要。项目①采用拟静力法开展了预制拼装桥墩抗震性能试验，进而开发了可更换耗能装置和震后节段损伤的快速处理策略，并进一步试验对比了添加可更换耗能装置及损伤节段CFRP加固试件的抗震性能，结果表明设置可更换耗能装置可提高预制拼装桥墩的滞回耗能、抗侧强度、刚度、自复位能力等抗震性能，通过损伤节段粘贴CFRP对提高桥墩水平承载力的效果并不显著，但能减缓桥墩水平承载力下降，使桥墩具有良好的塑性变形能力；为很好的模拟节段拼装，构建了一种干接缝单元成功实现了对节间的准确模拟，采用数值方法模拟了试验结果，进一步分析了各参数对预制拼装桥墩抗震性能的影响；②为提高预制拼装RC桥墩抗震性能研发一系列关键连接构造，包括卡扣式预制节段拼装桥墩连接装置、框架式可更换防屈曲减震耗能装置、可快速更换的预制桥墩塑性铰结构和可快速修复的预制BRB桥墩塑性铰结构等，并申报获批了国家发明专利；③通过理论分析和加速腐蚀试验，研究了氯离子腐蚀条件下钢筋锈胀、混凝土开裂特征，构建钢筋混凝土构件力学行为的时变模型；浇筑了缩尺桥墩模型，对其进行了电加速锈蚀和拟静力试验，结果表明桥墩构件在经历持续的腐蚀时，其耗能能力、抗侧能力、延性系数等抗震性能持续下降，同时腐蚀区的严重锈蚀也会引起曲率分布的显著变化，桥墩塑性铰有向腐蚀区转移的趋势；④基于钢筋混凝土构件的劣化规律构建了全寿命周期内滨海RC桥梁的抗震性能分析及地震易损性评估。本项目为预制拼装RC桥梁抗震设计及滨海RC桥梁的全寿命地震易损性评价提供理论基础，具有重要的理论意义和工程价值。