基于移动荷载谱的桥梁竖向自由振动最大响应研究  

Investigation of maximum vertical free vibration response of a bridge based on moving load spectrum

作　　者：李锦华[1,2] 张耀[2] 张焕涛 蓝声宁 LI Jinhua;ZHANG Yao;ZHANG Huantao;LAN Shengning(Department of Civil Engineering,East China Jiaotong University,Nanchang 330013,China;National Experimental Teaching Demonstration of Civil Engineering,East China Jiaotong University,Nanchang 330013,China;Department of Civil Engineering,Beibu Gulf University,Qinzhou 535011,China)

机构地区：[1]华东交通大学土木建筑学院,南昌330013 [2]华东交通大学土木工程国家实验教学示范中心,南昌330013 [3]北部湾大学建筑工程学院,广西钦州535011

出　　处：《振动与冲击》2021年第14期261-267,共7页Journal of Vibration and Shock

基　　金：国家自然科学基金(11962006)。

摘　　要：该研究提出了基于移动荷载谱的桥梁自由振动最大响应的频域分析法。该方法在频域内,采用傅里叶变换得到移动荷载作用在桥梁上的移动荷载谱及桥梁振动位移响应谱;并以理论推导与数值分析相结合的方法建立了移动荷载幅值谱最大值对应的无量纲速度与轴跨比(荷载轴距与桥梁跨径的比值)之间的关系;根据该关系提出了移动荷载作用下桥梁自由振动最大位移响应时的速度公式,该速度明显不同于共振速度。以两座不同跨径的简支梁桥为例,在时域内通过改变不同的轴跨比与移动荷载速度,计算桥梁自由振动最大位移响应,以此验证了频域分析结果的正确性。研究结果表明:基于移动荷载谱能够有效反映移动荷载作用下桥梁自由振动最大响应;当轴跨比为0.72时,引起的桥梁自由振动最大位移响应最小;当轴跨比为0与1.47时,引起的桥梁自由振动最大位移响应最大;移动荷载以速度公式获得的速度行驶,将会使得桥梁自由振动产生最大位移响应。A frequency domain analysis method based on moving load spectrum was presented for investigating the maximum free vibration response of a bridge.In frequency domain,the Fourier transform was used to obtain the moving load spectrum and the vibration displacement response spectrum of the bridge subjected to moving loads.Corresponding to the maximum value of the moving load amplitude spectrum,the relationship between the dimensionless speed and the axle-span ratio(the ratio of the load wheelbase to the bridge span)was established by the combined use of theoretical derivation and numerical analysis.Then according to the relationship,the speed expression of the maximum free vibration displacement response of the bridge under moving loads was proposed,it is obviously different from the resonance speed.Finally,taking two simply supported girder bridges with different spans as examples,the maximum displacement free vibration response of the bridges was calculated with different ratio of axle span to moving load speed in time-domain,in order to verify the correctness of the results of the frequency domain analysis.The results show that the maximum free vibration response of the bridge can be effectively reflected by moving load spectrum;when the axle-span ratio is 0.72,the maximum response of the bridge is the smallest;when the axle-span ratio is 0 or 1.47,the maximum response of the bridge is the largest;when the moving load travels at the speed according to the speed expression mentioned above,the maximum displacement free vibration response of the bridge will be generated.

关 键 词：移动荷载谱 自由振动 频域分析法 最大响应 轴跨比 移动速度 

分 类 号：TU352.1[建筑科学—结构工程]