FRP约束混合配筋桥墩基于可恢复性的抗震设计方法研究

Aiming at the severe problem that traditional reinforced concrete bridge columns tend to possess overlarge post-earthquake residual displacements, which has adverse impacts on the resilience of bridge structures and the emergency rescue service, a solving scheme that combines external fiber-reinforced polymer (FRP) wraps and hybrid FRP and steel rebars is proposed in this project, and investigations focusing on the resilience-based design method of such FRP confined hybrid reinforced bridge columns will be conducted. First, quasi-static tests and shake table tests which focus on the failure mechanism and damage control method will be performed, and the qualitative describing and quantitative distinguishing method for each damage level will be established. Second, accurate finite element simulation method which considering multiple complicate mechanism of FRP confined hybrid reinforced column will be proposed, and finite element analysis and theoretical analysis will be conducted to reveal the influences of design parameters on the inherent seismic performance and the dynamic responses under seismic excitations. Finally, the prediction method of post-earthquake residual drifts of the FRP confined hybrid reinforced column will be developed, and the resilience-based design method, which considers both maximum dynamic responses and post-earthquake residual displacements, will be proposed. Such a design method will also be compatible well with the current seismic design code of bridge structures. The research results of this project will contribute to providing the theoretical basis and scientific support to the development of the resilience-based bridge structure system and the corresponding innovative seismic design method.

针对混凝土桥墩残余位移过大而影响桥梁结构震后可恢复性能及灾后紧急救援效率的严峻问题，采用外部施加FRP约束−内部混合配置FRP筋与钢筋的综合解决方案，围绕新型FRP约束混合配筋桥墩基于震后可恢复性设计方法开展研究。首先，进行以损伤机理分析及控制方法为核心的拟静力及振动台试验研究，揭示FRP约束混合配筋桥墩在地震作用下受力变形特征和损伤演化机制，提出多级损伤状态定性描述方法及定量判别准则。然后，针对FRP约束混合配筋桥墩特有复杂力学机制，提出精细化建模方法并进行有限元分析，揭示设计参数对桥墩固有抗震性能及地震动力响应的影响规律。最后，发展FRP约束混合配筋桥墩震后残余位移预测方法，建立兼顾震时最大动力响应与震后可恢复性且与现行规范衔接良好的抗震设计方法。项目研究成果可为基于震后可恢复性新型桥梁结构体系及相应设计方法的发展完善提供理论依据及科学技术支撑。

传统钢筋混凝土桥墩在地震作用下易产生过大残余位移，显著影响桥梁结构震后通行能力及灾后重建效率，该问题对于我国量大面广的沿海地区氯盐腐蚀环境的桥梁而言尤为严峻。为解决此复杂科学问题，本项目围绕FRP约束FRP筋-钢筋混合配筋桥墩震后可恢复性能开展研究，主要内容及相应成果包括：（1）从材料、截面、构件、结构四个递进层次验证了外部FRP环向约束、内部FRP/钢混合配筋在减小桥梁结构全寿命周期内地震后残余位移的有效性及内在机理，揭示了FRP筋、FRP布内外联合使用时具有的“1+1>2”的突出力学优势及抵抗氯盐腐蚀的耐久性优势；（2）基于理论计算、抗震试验与有限元分析方法，明晰了FRP约束混合配筋桥墩在地震动力作用下的3阶段受力变形特征及在地震和氯盐腐蚀共同作用下的抗震性能演化机制，掌握了FRP筋材性、FRP筋-耗能钢筋配置比例等关键设计参数对混合配筋桥墩屈服后刚度比、累积滞回耗能、震后残余位移等重要震后可恢复性指标的影响规律，提出了多级损伤状态定性描述方法及定量判别准则，建立了兼顾地震时域内峰值响应与地震灾害后残余位移的基于可恢复性的抗震设计方法；（3）开展了应用FRP约束FRP筋-钢筋混合配筋方案提升氯盐腐蚀桥墩震后可恢复性的加固理论研究和抗震试验研究，提出了利用FRP材料耐腐蚀和高强度双重优势综合提高重要近海桥梁震后可恢复性及耐久性的创新思路、系统方案和实用建议。项目研究成果为FRP约束FRP筋-钢筋混合配筋桥墩的工程应用提供了分析理论、试验依据及技术支撑。