大跨度桥梁边墩横向减震体系的地震易损性分析

Fragility Analysis on Transversal Isolation System for Outer Piers of Long Span Bridges

摘要:

在大跨度桥梁中，边墩的竖向恒载与中墩相比往往较小，导致支座滑动摩擦力较小，因此，摩擦型耗能减震支座无法有效控制地震位移.针对以上问题，提出了滞回型钢阻尼器和滑动支座配合使用的桥梁边墩减震体系.然后，以一座大跨度钢桁架拱桥为例，建立了全桥有限元模型，以支座位移、墩底弯矩以及拱脚立柱的应力为工程需求参数，采用云图法建立概率地震需求模型，分析了该大跨度桥梁的边墩横向地震易损性.结果表明，采用滞回型钢阻尼器和滑动支座的桥梁边墩减震体系可有效降低桥梁上、下部结构各主要控制部位的横向地震易损性.

Abstract:

In common design of long span bridges, dead load on outer piers was much smaller than that on inner piers. As a result, under seismic excitation, energy dissipation for friction pendulum bearings on outer piers was not effective. In this regard, a new transversal isolation system consisting of a hysteretic damper and sliding bearing was proposed. After that, the effectivity of this system was validated by a modern steel trussed arch bridge using fragility function. Displacement of sliding bearings, bending moment of outer piers and stress on the arch springing were taken as the engineering demand parameters. Cloud method was applied to build the probabilistic demand seismic model. The generated fragility curves show that the proposed transversal isolation system performs quite well under potential earthquakes.