Research On Local Dynamic Response Of Steel Box Girder Of Suspension Bridge Based On Measured Data

With the extensive application of long-span suspension bridge in highway traffic,the problem of local damage of steel box girder caused by traffic load is becoming more and more prominent.Based on the measured data of local dynamic response of the girder,IMF energy method based on HHT theory is put forward to deal with the measured acceleration data of Runyang Bridge and analyze the regional sensitivity of dynamic response of steel box girder of suspension bridge under traffic load.The main work and research contents are as follows:(1)The classical theory and the modem theory of vehicle-bridge coupling vibration are summarized.The advantages and disadvantages of traditional methods for studying dynamic response,including real bridge test and numerical simulation method,are discussed.The advantages of dynamic response based on measured data are analyzed.(2)Several traditional time-frequency analysis methods are introduced such as Short-Time Fourier Transform,Wigner-Ville Distribution and Wavelet Transform,and their shortcomings are pointed out.Hilbert-Huang Transform based on empirical mode decomposition and Hilbert transform is chosen.The HHT analysis is carried out by numerical simulation signal,and the better processing effect is obtained.(3)A large number of acceleration response data are collected by using the Runyang Bridge Vibration Monitoring System.The data acquisition situation is analyzed and the missing data is preconditioned by linear interpolation.Comparing the acceleration time-history data collected at different periods,the data has non-stationary characteristics.And the time-sharing analysis is put forward to consider the influence of different periods of operating load.In order to further study the frequency composition of the acceleration response,the EMD method is used to decompose the acceleration data,and the instantaneous frequency analysis and marginal spectrum analysis of instantaneous mode functions are analyzed.The vibration frequency range of the bridge is obtained,which is composed of the first three intrinsic modal functions.(4)In order to analyze the regional sensitivity of dynamic response of steel box girder,the IMF energy index is put forward and verified by selecting data.The energy indexes of one day and the whole year were both compared to investigate the influence of ambient temperature on energy index.The change of the actual traffic data and the energy index are compared to investigate the influence of the vehicle load on the energy index.And the law of regional sensitivity of dynamic response is obtained by IMF energy analysis in the longitudinal and transverse direction and verified by selecting data.