Study On Dynamic Performance And Structure-Borne Noise Of High-Speed Railway Steel-Concrete Composite Box Girder Bridges

Steel-concrete concrete composite box girder bridge offers the advantages of high bearing capacity,strong spanning ability and favorable constructability,which has broad application prospects in high-speed railway bridges.However,with the rise of train speed,the structural vibration and radiated noise of railway bridges under train load stand out as a more and more prominent problem which cannot be ignored.Therefore,this dissertation carries out systematic research on the dynamic performance and radiated noise characteristics of high-speed railway steel-concrete composite box girder bridges from the aspects of theoretical model,field tests and numerical analysis.The main research works and results are as follows:(1)Based on the train-track-bridge interaction dynamic theory,the dynamic simulation model of high-speed railway steel-concrete composite bridge is established.The simulation analysis program is compiled based on Python language and Ansys finite element software.(2)Based on the indirect boundary element method and statistical energy analysis method,the structure-borne noise prediction model of high-speed railway composite bridge is established.Combined with the train-track-bridge interaction dynamic simulation program,the full-frequency band acoustic and vibration response analysis model of high-speed railway composite bridge is proposed.The current acoustic environmental assessment standards are summarized and the influence of low-frequency structure-borne noise is discussed.(3)Field tests of high-speed railway bridges are carried out.The structural vibration and radiated noise of a 5×50 m continuous composite box girder bridge and a 32 m simply supported concrete box girder bridge are measured under train passing loads.The acoustic and dynamic performance of high-speed railway composite box girder bridge are analyzed,and the difference between the composite bridge and the concrete bridge is discussed.Based on the measure data,the accuracy of the simulation model is verified,and the acoustical contribution at the field point is analyzed.(4)Numerical analysis on the simply supported composite box girder bridges with different spans and the continuous composite box girder bridge is carried out.The structural vibration and sound radiation responses of the bridges under the action of train loads at different speeds are calculated.The safety and stability of the trains and bridges are verified,and the dynamic performance and sound radiation characteristics of the composite box girder bridges are investigated.Subsequently,the effects of plate thickness,bottom concrete layer,shear connection degree and uplift-restricted and slip-permitted connection on the sound and vibration performance of the composite box girder bridges are further explored.(5)The influence of steel web stiffeners on the statistical energy analysis parameters of the plate and the sound and vibration response of the structure is analyzed.The effects of stiffener layout spacing,stiffener size and width-thickness ratio are also revealed.Based on the consideration of the optimal steel consumption and the effect of vibration and noise reduction,the optimal layout of the steel web stiffeners is proposed.