环境激励下人行桥振动时频分析

Time-frequency Analysis of Pedestrian Bridge Vibration under Environmental Excitation

为研究人行桥在不同环境激励下的振动响应规律,采用Hilbert-Huang变换对某人行桥在噪声激励、车辆荷载、行人荷载以及车辆-行人荷载耦合激励条件下的加速度响应进行分析。结果表明:噪声激励、车辆荷载、人行荷载、车辆-行人耦合激励条件下人行桥的加速度响应幅值逐渐增大,脉冲指标呈逐渐增加的趋势,功率谱幅值不断向高频段偏移。四种激励下,人行桥的加速度响应经过经验模态分解后的前五阶本征模态函数的方差贡献率及相关系数较大,且瞬时振幅和瞬时频率呈减小趋势;其能量分布随加速度幅值的增大逐渐增大,车辆荷载作用下其能量熵值最小,能量分布相对均匀。Hilbert-Huang变换对处理复杂环境激励下的桥梁振动响应具有较好的识别效果,分析过程可为同类振动信号处理所借鉴。

In order to study the vibration response law of the pedestrian bridge under different environmental excitations,the Hilbert-Huang transform was used to analyze the acceleration response of a pedestrian bridge under the conditions of noise excitation,vehicle load,pedestrian load and vehicle-pedestrian load coupled excitation.The results show that the amplitude of the acceleration response of the pedestrian bridge increases gradually under the conditions of noise excitation,vehicle load,pedestrian load and vehicle-pedestrian coupling excitation.The pulse index increases gradually,and the power spectrum amplitude continuously shifts to the high frequency band.Under the four excitations,the acceleration response of footbridge after empirical mode decomposition of the first five order intrinsic mode functions variance contribution rate and correlation coefficient are large,and the instantaneous amplitude and instantaneous frequency show a decreasing trend.Its energy distribution area increases gradually with the increase of acceleration amplitude.Under the action of vehicle load,its energy entropy value is the minimum,and the energy distribution is relatively uniform.The Hilbert-Huang transform has a good recognition effect on the vibration response of bridges under the excitation of complex environment.The analysis process can be used for the similar vibration signal processing.