设置BRB的桥梁排架墩抗震性能参数分析

汶川大地震中，桥梁双柱式排架墩遭到了严重的破坏，其抗震问题被广泛关注。作者基于结构“保险丝”的损伤控制理念，在双柱式桥梁排架墩中设置屈曲约束支撑（BRB），以提高横桥向的抗震性能。建立了考虑墩柱弹塑性、梁体与挡块碰撞和支座滑动效应的单个排架墩动力分析模型，通过输入远场地震动、具有向前方向性效应和滑冲效应的近断层地震动进行非线性地震反应时程分析，研究了BRB与排架墩水平刚度比、水平屈服位移比、BRB布置形式和排架墩形式等参数对桥梁排架墩抗震性能的影响。结果表明：设置BRB能有效地减小规则和不规则排架墩的地震损伤，BRB与排架墩水平刚度比和水平屈服位移比的合理取值范围分别为0.5～2.0和0.5～1.5。

Parametric Analysis of Seismic Performance for Bridge Bents with Buckling-restrained Braces (BRBs)

During Wenchuan earthquake, some bridge bents with double piers suffered severe damage and much attention has been paid to the seismic performance of bridge bents. Based on the structural fuse concept, the bridge bents by using buckling-restrained brace (BRB) was proposed to control its damage in transverse direction. An analytical model of single bridge bents considering the elasto-plastic behaviors of piers, the pounding response between shear keys and girders and the sliding friction behavior of laminated rubber bearing was developed. Nonlinear response history analyses were conducted with far-fault and near-fault ground motion records including velocity pulse of forward rupture directivity effect and fling-step effect. Many parameters such as the ratio of horizontal stiffness between BRBs and bents, the ratio of horizontal yielding displacement between BRBs and bents, the arrangement form of BRBs, the bent with unequal-high piers, and the intensity of ground motion were analyzed. Results indicated that the damage of regular and irregular bridge bents can be effectively controlled by using BRBs, and the rational sampling ranges of the horizontal stiffness ratio and horizontal yielding displacement ratio between BRBs and bents are found to be 0.5~2.0 and 0.5~1.5, respectively.