弹性支承边界条件对桥梁共振与消振的影响机理分析  

Mechanism analysis of influence of elastic support boundary conditions on bridge resonance and cancellation

作　　者：陈雷[1] 杨永斌 王志鲁 刘志勇[1] 姚华[1,2] Chen Lei;Yang Yeongbin;Wang Zhilu;Liu Zhiyong;Yao Hua(Chongqing University,Chongqing 400045,China;Chongqing Communication Engineering Quality Testing Co.,Ltd.,Chongqing 400067,China)

机构地区：[1]重庆大学,重庆400045 [2]重庆市交通工程质量检测有限公司,重庆400067

出　　处：《土木工程学报》2024年第6期13-25,共13页China Civil Engineering Journal

基　　金：国家自然科学基金项目(52008057)。

摘　　要：铁路桥梁服役过程中,因支座病害和冲刷等作用,桥梁端部约束常发生弱化。该文旨在理论解析边界支承条件及其变化对桥梁动力特性及共振与消振条件的影响机理。文章首先提出考虑左右支承刚度不等的弹性支承梁振型的简化表达,建立了移动连续荷载作用下弹性支承梁自由振动的理论闭合解;然后推导考虑左右支承刚度不等的桥梁共振与消振条件,理论解析桥梁-支承刚度比(刚度比)、左右支承刚度不等比(刚度不等比)的影响机理;最后通过数值模拟验证理论解的准确性,并参数化分析支承条件参数对桥梁动力特性及共振与消振条件的影响规律。研究结果表明:(1)弹性支撑梁的频率随弹性支承的刚度比和刚度不等比增大而减小;(2)弹性支承梁的共振与外部消振速度参数与简支梁一致,但共振与外部消振速度降低,更易激发共振与外部消振;(3)支承条件对桥梁内部消振条件影响大,当左右支承刚度相等时,存在唯一内部消振条件,否则不发生内部消振;(4)当桥梁支承弱化或者两侧刚度不等时,基于简支梁的最佳跨长对共振的消除效应将逐渐失效;(5)阻尼有利于抑制桥梁共振幅值,对外部消振存在微小的非零值“阻尼泄露效应”;(6)当两侧支承刚度不相等时,桥梁最大响应位置偏离桥梁跨中,需在桥梁检测时关注。During the service life of railway bridges,the end constraints of bridge may often be weakened due to the actions of bearing defects,erosion,etc.This work aims at theoretically analyzing the influence mechanism of boundary support conditions and the corresponding variations on the dynamic characteristics as well as the resonance and cancellation conditions of bridges.Firstly,a simplified expression for the vibration mode of an elastically supported beam considering unequal left and right support stiffness is proposed,and then the theoretical closed-form solution for the free vibration of an elastically supported(ES)beam under the action of moving continuous loads is established.Secondly,the resonance and cancellation conditions of the ES beam are derived,and the influence relationship of bridge resonance and cancellation due to the stiffness ratio(SR)of bridge to support and stiffness inequality ratio(SIR)of the left and right supports is theoretically analyzed.Finally,the accuracy of the theoretical solution is verified through numerical simulation,and the impact of support condition parameters on the dynamic characteristics as well as resonance and cancellation conditions of bridges is parametrically analyzed.The results show that:(1)The frequency of the ES beam decreases with the increase of the SR and SIR of elastic support.(2)The resonance and external cancellation speed parameters of the ES beam are consistent with those of a simply-supported(SS)beam,but the resonance and external cancellation velocities decrease,making it more prone to resonance and cancellation.(3)Support conditions may significantly affect the internal cancellation conditions of bridges.If the left and right support stiffness are equal,there is only one unique internal cancellation condition;otherwise,the internal cancellation does not occur.(4)If the bridge support is weakened or the stiffness on both sides is unequal,the resonance cancellation effect of the optimal span length based on the SS beam may gradually diminish.(5)Damping shal

关 键 词：铁路桥梁 弹性支承梁 共振 消振 不等支承 

分 类 号：U441.3[建筑科学—桥梁与隧道工程] U24[交通运输工程—道路与铁道工程]