简支梁桥形状记忆合金装置减震防落研究

SMA restrainers for unseating prevention of a simply supported bridge

进行了直径为8 mm的国产形状记忆合金棒材拉伸试验,由实验数据拟合得到其基本力学模型参数。以一座3跨简支梁桥为例,基于日本桥梁抗震规范设计形状记忆合金减震防落装置。采用ABAQUS有限元分析软件建立该简支梁桥有限元分析模型,进行地震响应动力时程分析。研究形状记忆合金防落装置初始间隙、装置长度对防落效果及桥墩内力的影响规律,且与传统的钢绞线防落装置进行了对比分析。研究结果表明减少形状记忆合金装置长度与初始间隙,碰撞现象和墩梁相对位移会减少,但墩底剪力会相应增加;形状记忆合金防落装置对碰撞与墩梁相对位移的控制效果优于钢绞线防落装置。

Tensile tests of home-made Ni-Ti SMA bars were conducted,the parameters of its basic mechanical model were determined with curve fitting of tested stress-strain data.Taking a 3-span simply supported bridge as an example,SMA aseismic restrainer was further designed based on Japanese bridge aseismic specifications and the tested stress-strain data.Its finite element model was further established with ABAQUS.Its dynamic response＇s time-history analysis was performed to investigate the effects of restrainer length and initial gaps on the efficiency of the restrainer and the bridge＇s internal forces.The comparison of the SMA restrainer and a traditional steel cable restrainer was made.The simulated results showed that the relative displacement between bridge girder and pier and pounding between two bridge girders decrease with decrease in SMA restrainer length and initial gap;however,the shear force at pier bottom increases;the control effect of the SMA restrainer on the pounding between two bridge girders and the relative displacement between bridge girder and pier is better that that of the traditional steel cable restrainer.