设置BRB构件的双柱式桥墩的横桥向减震分析

Analysis on transverse damping performance of double column pier with BRB

以某3×30 m公路高架桥为工程背景,采用非线性时程反应分析法,研究了两种不同墩高下BRB的设置方式及核心段材料屈服强度σ(80~235 MPa)对桥梁地震反应的影响规律。结果表明:(1)设置BRB的双柱式墩在横桥向地震作用下减震效果显著,具体减震效果与BRB的屈服耗能及改变上部结构地震力在桥墩体系中的传力路径双重因素有关。(2)对9 m高双柱式墩,BRB的最优布置为单斜杆形式。当BRB的核心段屈服应力σ取值较大时,BRB将不进入屈服,通过其侧向刚度改变结构体系的传力路径。(3)对18 m高双柱式墩,BRB的最优布置为双平行斜杆布置。BRB的减震效果随着σ的增大而增加,在σ取值较大值时,BRB起改变传力路径及滞回耗能的双重作用。(4)在双柱式桥墩中合理设置BRB并取其最优力学参数,可有效改善桥梁下部结构的抗震性能。对本文算例,9 m和18 m高双柱式墩墩底弯矩减震率分别为34%和44%。

Taking a 3 × 30 m highway viaduct as engineering background,the method of setting BRB and yield strength of core segmentσ( 80 ~ 235 MPa) on the seismic response of bridge with two different pier height are studied by adopting method of nonlinear time history response analysis. Results shows:( 1) The effect of the double column pier with BRB on the seismic response of the bridge is significant,and the specific damping effect is related to the yield energy consumption of BRB and the change of the seismic force of the superstructure in the bridge system.( 2) For 9 m high double-column pie,the optimal arrangement of BRB is in the form of a single rod. When the core section of BRB yield stress valueσ is large,BRB will not enter the yield,through the force transmission path structure of its lateral stiffness change;( 3) For 18 m high double-column pie the optimal layout of BRB double parallel oblique rod arrangement. The damping effect of BRB increases with the increase of σ,When theσ is larger,BRB plays a dual role in changing the load path and hysteretic energy dissipation.( 4) The reasonable performance of the BRB and the optimum mechanical parameters can be effectively improved in the double column piers. For the example of this paper,9 m and 18 m high moment at the bottom double-column Pier damping rates were 34% and 44%.