Separation And Extraction Method Of The Quasi-static Response In Bridge Utilizing The Wavelet Packet

The quasi-static response is an essential parameter in the calculation of dynamic impact effect in bridge.Additionally,the quasi-static deflection and stress are certificated to be efficient in the techniques which aim to investigate the dynamic character and evaluate the structural performance of bridges.In previous studies,the quasi-static response of bridge was principally obtained by numerical simulation or vibration signal inversion.However,the previous methods are impeded in practical application by the assumption or complicated calculation.It would greatly improve the efficiency of dynamic detection and assessment for bridge in case that the quasi-static component can be directly separated and extracted from the origin vibration signal.For this aim,the specific works were carried out:(1)The road roughness was simulated with the sum of harmonic superposition.Then analytical expressions of the static response and dynamic response of a simply supported beam are derived.Based on further frequency component analysis,a method which can perform extracting progress of the quasi-static response in bridge is proposed by utilizing the wavelet packet transform.(2)A 2-D vehicle-bridge coupling vibration model was adopted and solved by the program developed in the MATLAB.The quasi-static components were extracted by the proposed method,in which parametric study was carried out respectively with vehicle speed,road surface condition and signal correlation in terms of the influence to the extraction results.(3)The wavelet packet based method was verified by a numerical simulation case,in which a 3-D vehicle-bridge coupling vibration system was solved.The separation and extraction results of quasi-static deflection and strain were certified in comparison with the accurate time history.Furthermore,the variation of the global extraction error was discussed considering the boundary distortion and apparent local error caused by the asymmetry of wavelet basis.(4)Utilizing the 3-dimensional vehicle-bridge coupling analysis model,9 load cases was simulated in multi-vehicles.Various parameters including traffic flow speed,vehicle spacing,multi-vehicle speed and partial loading on the deck slab were presented to explored the effects to the extraction result.