自复位全预制装配双柱式RC桥墩抗震性能及能力提升

Accelerated bridge construction has become a next generation of bridge engineering, attracting wide attention of engineering construction management department and academia at home and abroad. Key construction detail and performance of prefabricated assembly bridge piers are the key issue of accelerated bridge construction. Seismic performance and design method of complicated precast assembly RC bridge bent system need more exhaustive exploration in depth. Fully-prefabricated assembly double-column RC bridge piers are chosen as the research object in this proposal. Based on former research basis, considering three levels from materials/interface, member to structural system, three methods of theoretical analysis, numerical simulation and model experiment are adopted. The key constructional details of self-centering fully-prefabricated assembly bridge bent system are proposed and nonlinear behavior of segmental piers and key joints are investigated. Exact models and resilient models of key interface, joint and energy dissipators. Nonlinear behavior, damage mode and failure mechanism of self-centering fully-prefabricated assembly bridge bent system are illuminated. The ultimate objective of this proposal is evaluating the seismic performance, e.g. displacement ductility, lateral strength, lateral stiffness, energy dissipation capacity, self-centering capacity and establishing the performance-based seismic design method of the fully-prefabricated assembly bridge bent system. This research will promote improvement of accelerated bridge construction technology, providing theoretical basis and technical support of R&D and engineering exemplification of prefabricated assembly bridge bent system.

桥梁快速建造技术已成为下一代桥梁工程的发展方向，受到国内外工程建设部门和学术界的广泛关注。预制装配化桥墩关键构造及性能是桥梁快速建造技术亟待解决的关键问题。复杂受力的装配化双柱RC桥墩体系抗震性能及设计方法有待进一步深入研究。本项目以全预制装配双柱RC桥墩体系为研究对象，从材料/界面、构件到结构体系三个层次通过理论分析、数值模拟和模型试验等手段，研发自复位全预制装配双柱RC桥墩体系的关键构造，开展预制拼装桥墩及关键节点构造的非线性力学行为研究，建立关键界面、节点及耗能部件的精细化模型和恢复力模型，揭示自复位全预制装配双柱RC桥墩体系的非线性行为、失效模式及破坏机理，评估自复位预制装配桥墩体系的位移延性、抗侧强度和刚度、耗能能力、自复位能力等抗震性能，最终建立基于性能的抗震设计方法。本项研究为完善桥梁快速建造技术，推动预制装配桥墩系统研发和工程示范提供重要的理论基础和技术支撑。

基于新型预制节段拼装钢管混凝土桥墩的拟静力往复试验结果，考虑接缝非线性接触、预应力筋线性本构、钢管和混凝土非线性本构关系，建立了预制节段钢管混凝土桥墩的数值模型，数值分析了预制节段拼装钢管混凝土的自复位能力和抗震性能及其主要影响因素。研究结果表明，所发展的自复位预制节段拼装CFST桥墩具有良好的竖向和抗侧承载能力以及良好的自复位能力。但是如果没有附加耗能部件，其耗能能力有限。.针对现有自复位预制拼装桥墩抗侧强度计算方法，提出两种简化的自复位节段拼装桥墩计算分析模型。通过数值模拟和试验对所提出的单开口简化分析模型进行验证，结果证明所提出的模型与试验和数值模拟结果吻合良好。针对无粘结预应力筋的预应力损失问题，开展了双柱摇摆桥墩试验研究发现自复位摇摆结构在偶然荷载作用下的预应力损失来源主要是预应力变化过程中引起的锚具夹片回缩造成的。对预应力变化引起锚具夹片的回缩进行了锚具回缩试验研究，提出了锚具回缩值和预应力筋内力增量的关系表达式，并将其引入自复位节段桥墩理论分析公式中提高计算精度。对通用有限元软件ABAQUS进行二次开发，采用UMAT子程序开发了锚具材料，所开发的锚具材料本构模型可以较好地考虑夹片回缩引起的预应力损失。.开展了全预制自复位双柱式桥墩的抗震性能研究。研究了全预制自复位双柱式桥墩的承载、耗能及自复位机理和力学行为，分析了各受力阶段自复位双柱式桥墩的变形和受力协调条件，建立了阻尼器和无粘结预应力束设计方法及整体结构基于位移的抗震设计方法。制作了三组大比例尺缩尺预制双柱墩模型，并开展了拟静力试验研究。研究了拟静力往复加载过程中接缝开口、预应力张拉力和耗能阻尼器的力学行为，优化了耗能组件及其连接方式。开展了单跨自复位预制拼装桥梁的振动台试验研究，分析了地震动激励作用下桥梁加速度和位移动力反应，以及接缝开口和耗能组件的变形情况。试验验证了所设计的自复位双柱式桥墩的抗震能力。

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