Vibration Analysis Of Vehicle-bridge Coupling And Research Of Local Fatigue Of Steel-concrete Composite Girder Bridge

Steel-concrete composite girder bridges have been increasingly used in recent years because of their advantages of both steel and conc rete.However,the vibration rules of steel-concrete composite girder bridge under the action of vehicle is obviously different from that of general concrete girder bridge,and the steel-concrete composite girder bridge is prone to fatigue failure during u se.Therefore,it is of great significance to study the vibration rules of vehicle-bridge coupling and fatigue life of steel-concrete composite girder bridge.In this paper,firstly,the vehicle-bridge coupling vibration equation is established,and the Newmark-β method is selected to solve it.The solution process is realized by ANSYS.The analysis program of vehicle-bridge coupling is written by APDL language,and the vibration responses of vehicle-bridge coupling is solved in ANSYS.Then,based on the vibration responses,the vibration rules of vehicle-bridge coupling,the change rules of impact coefficient and the fatigue life are studied.The specific research contents are as follows :(1)In order to study the vibration rules of vehicle-bridge coupling of steel-concrete composite girder bridge,based on ANSYS,the vibration responses of the bridge under different vehicle speed,vehicle weight,bridge roughness,the thickness of bridge deck and the height of web of main beam are calculated in this paper,and the influence of different factors on the vibration responses of the bridge is analyzed.Based on the Sperling comfort index,the influence of different factors on pedestrian comfort and driving comfort is analyzed,and the measures are given to improve pedestrian comfort and driving comfort.(2)The impact coefficient of the steel-concrete composite beam bridge is different at different positions of the br idge.In order to study its distribution rules,this paper first analyzes the variation rules of the impact coefficient of different transverse and longitudinal positions of the bridge,and gives the reasonable transverse and longitudinal positions when ca lculating the impact coefficient.Secondly,the difference between the strain impact coefficient and the displacement impact coefficient of the steel-concrete composite girder bridge is compared and analyzed,and the applicability of the two impact coeffic ients is studied.Thirdly,the variation rules of impact coefficient under different bridge roughness is analyzed,and the variation rules of impact coefficient with time is studied based on the bridge deck degradation model,so as to provide reasonable maintenance time of bridge deck for bridge maintenance department.Finally,the numerical simulatio n results are compared with the field driving test to verify the correctness of the simulation method of displacement impact coefficient and strain impact coefficient,and the service condition of the bridge is evaluated.(3)In order to study the fatigue damage and fatigue life of the main girder of the steel-concrete composite girder bridge under the action of vehicles,this paper first calculates the dynamic stress of the fatigue detail of the bridge under different vehicle speeds,vehicle weights,bridge deck roughness,the thickness of bridge deck and the height of web of main girder,and analyzes the influence of different factors on the dynamic stress,stress amplitude,the impact coefficient of stress amplitude and the number of equivalent stress amplitude.Then,the influence of various factors on the fatigue damage of the main girder under the action of single vehicle is analyzed,and the influence of various factors on the cumulative fatigue damage of the main girder is studied considering the degradation of the bridge deck.Finally,the fatigue life of the steel-concrete composite girder bridge under different factors i s analyzed,and the measures to prevent the fatigue failure of the bridge are given.