车辆荷载作用下简支梁桥动力特性分析及模态参数识别

DYNAMIC CHARACTERISTICS ANALYSIS AND MODAL PARAMETER IDENTIFICATION OF SIMPLY SUPPORTED BEAM BRIDGE UNDER VEHICLE LOAD

为研究车辆荷载作用对简支梁桥结构动力性能的影响,对车辆荷载作用下的简支梁桥进行能量分析并采用随机子空间法(SSI)和RDT-STD法对简支梁桥进行模态参数识别研究。分析不同车速激励下的桥梁能量分布情况,对比不同模态参数识别方法的频率、阻尼和振型的识别结果。结果表明:随着车速的增加,简支梁桥的加速度幅值不断增大,能量向高频段偏移,更容易激发结构的高阶模态;随机子空间法(SSI)和RDT-STD法均能有效识别出简支梁桥的竖向频率,SSI法对于简支梁桥频率和阻尼的识别精度高于RDT-STD法,但两种识别方法对阻尼的识别相对误差较大,且存在一定的离散性。

To study the effect of dynamic performance of vehicle load on simply supported beam bridge structure,in the paper, the energy analysis of a simply supported beam bridge under vehicle load was carried out.The modal parameters identification of simply supported beam bridge was carried out with the stochastic subspace identification method(SSI) and the RDT-STD method.The energy distribution of bridge under different driving speeds was analyzed.The frequency, damping and vibration modal recognition results of different modal parameter identification methods were compared.The results showed that,as the vehicle speed increased, the amplitude of the acceleration response of the simply supported beam bridge increased continuously, and the energy shifted to the high frequency band, which made it easier to excite the higher-order mode of the structure. The SSI method and the RDT-STD method could identify the vertical frequency of the simply supported beam bridge effectively.The frequency and damping identification accuracy of SSI method was higher than that of RDT-STD, but the two identification methods had large relative errors in the identification of damping, and there was a certain discreteness.