装配铅挤压阻尼器的摇摆-自复位双柱墩抗震性能及设计方法

为发展具有损伤可控和自复位性能桥梁双柱墩，选取铅挤压阻尼器(lead-extrusion dampers, LEDs)为可更换耗能装置，并通过预应力筋提供自恢复力，组成摇摆-自复位(rocking self-centering, RSC)双柱墩体系(RSC-LEDs)；通过对其抗震性能的研究，对应发展了一种基于等能量设计流程(equivalent energy-based design procedure, EEDP)的设计方法。首先建立了RSC-LEDs双柱墩的数值分析模型，结合一RSC双柱墩试件的拟静力结果验证了建模方法的正确性。在此基础上，定性分析了阻尼器出力、初始预张拉力、无粘结预应力筋配筋率、上部结构重量及盖梁-墩柱刚度比对RSC-LEDs双柱墩滞回性能的影响。设计了32组不同参数的RSC双柱墩试件开展回归分析，并结合RSC-LEDs双柱墩的力学特性，得到了RSC-LEDs双柱墩等效屈服强度、刚度的半经验计算公式。结合中国公路抗震设计规范和EEDP，提出一种适用于RSC-LEDs双柱墩体系的两阶段抗震设计方法，设计案例分析表明:半经验计算公式可较为准确地估算RSC-LEDs双柱墩的等效刚度及屈服强度；所提出的设计方法可使RSC-LEDs双柱墩达到预期的能力曲线，并实现在E1地震作用下保持弹性，在E2地震作用下LEDs屈服耗能且地震位移需求得到控制的设计目标。

SEISMIC PERFORMANCE AND CORRESPONDING DESIGN METHOD OF ROCKING SELF-CENTERING BRIDGE BENTS EQUIPPED WITH LEAD-EXTRUSION DAMPERS

To develop the self-centering two-column bents and achieve the seismic damage control, lead-extrusion dampers (LEDs) were selected as the external energy dissipaters, and a rocking self-centering bridge bent system equipped with LEDs was proposed. The seismic performance of this system was studied, and a corresponding design method which was based on the equivalent energy-based design procedure (EEDP) was developed. Initially, the numerical analysis model of RSC-LEDs bridge bent was established, and the simulation method was validated by an existing cyclic test of a RSC bridge bent specimen. Then the effect of LED output force, gravity load of superstructure, prestressing force, areas of unbonded tendon and cap beam-to-column stiffness ratio on the seismic performance of RSC-LEDs bridge bents was studied. 32 RSC bridge bents with different parameters were designed to conduct regressive analysis, and semi-empirical formulas were given to calculate the effective stiffness and yield strength of RSC-LEDs bridge bents. Combining the Chinese seismic code and EEDP, a two-stage seismic design method was proposed for RSC-LEDs bridge bents, and the results show that the obtained semi-empirical formulas can estimate the effective stiffness and yield strength accurately. The RSC-LEDs bridge bents designed by the proposed method can achieve the target capacity curve, and is able to remain elastic under E1 level earthquake. The LEDs start to dissipate energy under E2 level earthquake and the seismic displacement demand can be controlled within a design range.