FRP抗震加固改造支座/RC桥墩串联体系的抗震性能研究

With the application of ductility and seismic isolation idea to bridge design, bearings and bridge piers are used to number of highway road bridges, which forms to series seismic isolation system, and interactively complete the ductility and dissipation energy mechanism. So the bearing and bridge are determined as the key components in seismic retrofitting and reforming of bridge. Firstly, based on the simulated performance results of series seismic isolation system with bearings and bridge piers, the mechanical formulas under damage modes is proposed. And then according to the behavior requirement of bearings and bridge piers under damage modes, the target performance parameters of seismic retrofitting to bridge piers were determined, which are used to present the relativity with strengthened parameters of Fiber Reinforced Polymer. In view of that, un-strengthened and strengthened series seismic isolation systems are designed, and seismic performance experiment of components are carried out. The experimental seismic behavior and damage modes are analyze for tested models, which are compared with theory results to verify the correct of the above proposed mechanical models. In the end, a reinforced concrete girder bridge is taken as an example, the proposed the mechanical formulas of series seismic isolation system and seismic retrofitting design method for bridge piers, and finite element technology is used to analyze the effect of performance improvement of mechanical formulas on damage modes and seismic performance, then adjusting retrofitting and reforming plan. On the basis of the contribution of series seismic isolation system to seismic performance of the bridge, the existing retrofitting and reforming plan with single component behavior improvement is optimized, and the new method is facilitate to practical bridge engineering application.

随着延性和减隔震设计理念的引入，大量公路桥梁中支座和桥墩组成串联体系，地震中共同完成桥梁整体延性耗能机制。因此，支座和桥墩成为桥梁抗震加固改造的重点。首先，根据支座/桥墩串联体系的受力性能模拟结果，建立不同损伤模式下其力学性能计算公式。然后，根据不同损伤模式下支座和桥墩的受力性能需求，确定RC桥墩的抗震加固性能目标参数，建立该参数与纤维增强复合材料（FRP）加固参数之间的关系。据此，设计并实施未加固和加固串联体系的抗震性能试验研究，分析其抗震性能和损伤模式，与理论分析结果进行对比，验证以上计算模型的正确性。最后，以某一座RC梁桥为例，应用以上串联体系力学性能计算公式和桥墩抗震加固设计方法，结合有限元分析技术，分析串联体系性能改善对整桥损伤模式和抗震性能的影响，调整加固改造方案。研究串联减隔震体系对桥梁抗震性能的贡献，优化并完善改善单一构件性能的桥梁抗震加固改造设计方法，且便于实际工程操作。

以我国量大面广的公路梁桥体系为研究对象，从支承构件普通橡胶支座、支座/RC桥墩局部串联结构着手，首先基于既有局部串联结构体系力学关系模型，提出影响其力学性能的敏感参数，主要包括支座和墩柱力学指标及界面连接方式。进而，采用模型试验、数值模拟和理论研究相结合的方法，设计并实施了水平荷载作用下普通橡胶支座抗剪性能研究方案。研究结果表明，支座接触界面的摩擦滑移、脱空，可影响支座的损伤破坏模式，显著降低其有效剪切性能的发挥。水平循环荷载作用下，水平滑动位移不易完全恢复。支座剪切变形小于100%时，支座剪切刚度实测值较设计值小，最大相差24.3%。另外，老化支座的宏观剪切刚度增加，其增加程度明显大于剪切模量，而剪切变形能力降低。.进一步考虑支座界面接触方式、界面摩擦参数、支座剪切性能、轴压荷载等参数，应用有限元数值模拟方法，对橡胶支座/桥墩串联体系的水平受力性能进行敏感参数分析。研究结果表明：支座连接方式可显著影响水平及效模式，提出了串联体系力学关系模型。据此，设计并实施了未加固与FRP加固橡胶支座/RC墩柱抗震性能研究方案。研究结果表明：支座类型、界面连接条件、轴压比，墩柱性能等参数，可显著影响串联体系的抗震性能。其中，水平荷载作用下，支座连接界面发生摩擦滑移（摩擦系数0.1），则该类串联体系的水平位移-水平力滞回曲线较饱满，但由于界面摩擦可降低水平力传递给下部结构，使得下部墩柱的侧向位移较小，不能充分发挥墩柱的抗震性能。而界面接触摩擦系数较大（0.2）的串联体系，其关键组成部分的侧向变形及耗能能力均得到提高，多以墩柱弯曲损伤失效模式为主。此外，通过FRP加固下部墩柱，可明显改善普通板式橡胶支座/RC墩柱串联体系的耗能，降低延性构件的变形性能，但对四氟滑板橡胶支座/RC墩柱串联体系的抗震性能改善不明显。因此，不同参数对串联体系抗震性能指标的影响程度不同，对进一步开展桥梁工程的抗震加固改造性能提供了一定的理论和数据支撑