设置BRB桥梁排架墩基于位移抗震设计方法

摘要

基于“保险丝”和“损伤控制”的抗震设计理念,提出在桥梁双柱式排架墩中通过设置屈曲约束支撑(BRB)以提高其横桥向抗震性能的构想.首先从获得“抗震能力”的角度对设置BRB桥梁排架墩的抗震设计参数进行系统性分析,推导出与剪跨比和墩柱间距与直径(边长)比相关的BRB核心段最大和最小长度取值范围;再从求解“地震需求”角度建立了设置保险丝的(SDOF)主结构体系弹塑性反应谱基本方程,分析该体系的非线性地震反应一般规律;然后,基于体系的“抗震能力”和“地震需求”,发展了设置BRB的桥梁排架墩基于位移的抗震设计方法,并结合一个具体桥梁排架墩实例说明建议设计方法的可行性.%Based on the concept of structural fuse,the buckling-restrained braces (BRBs) were proposed to be used in the bridge bents with double columns to improve the seismic performance of bridge in transverse direction.The seismic design parameters of bridge bents with BRBs were systematically analyzed.The relationship between length of the BRBs core and shear span ratio,the ratio of intercolumniation and diameter or side length of the pier section is derived from the viewpoint of seismic capability for the new structural system,and the length range of core section of BRBs was also determined.The elasto-plastic response spectra for a single-degree-of-freedom (SDOF) system with structural fuse was developed from the perspective of seismic demand,so that they are given in a format of easy use for the design of similar structures with a wide range of response characteristics.Furthermore,the displacement-based design method of bridge bents with BRBs was proposed based on the seismic capability and demand.Finally,the feasibility of the proposed method was validated by using the seismic design for a bridge bent example.