Response Analysis Of Vehicle-Bridge Coupling System Based On Spatial Bridge Deck Roughness

The research of bridge vibration response under moving vehicle load has been paid much attention in bridge field.A large number of studies have shown that the bridge deck roughness is one of the sensitive factors affecting the vibration of vehicle bridge coupling system,and the numerical simulation of the bridge deck roughness is generally based on the relevant specifications,and it is assumed that the excitation from the bridge deck at the wheel is smooth,but the bridge response caused by the change of vehicle trajectory and the randomness of the spatial distribution of the bridge deck roughness is rarely considered Machine vibration.Therefore,it is of great significance and engineering value to study the vibration response of vehicle bridge coupling system based on the spatial bridge deck roughness and vehicle trajectory randomness.As a part of the National Natural Science Foundation of China(51978063),this paper studies the measurement of spatial deck roughness and its influence on the response of vehicle bridge coupling system.Firstly,based on the theory of rigid body dynamics and vehicle dynamics,the vibration differential equations of 1/4 vehicle model,1/2 vehicle model and whole vehicle model are established.On this basis of the vehicle model,the vibration equation of vehicle bridge coupling system is established,and the program is compiled for analysis and validated.Secondly,taking the simply supported beam bridge as the research object,the three methods of three meter ruler,acceleration sensor and smart phone are used to compare and study the test of the bridge deck roughness,and the multi thread field test of the bridge deck roughness is carried out,and the spatial bridge deck roughness model is constructed.Then,by simulating the random driving path of vehicles,the coupling between vehicle and bridge is studied Considering the influence of system vibration response,based on the bridge dynamic response of 500 groups of vehicles under random driving state,the probability distribution model of bridge impact coefficient under different vehicle travel paths and the change law of bridge impact coefficient under different vehicle speeds are analyzed.Then,based on the current roughness specification,the triangular function superposition method is used to conduct numerical simulation of bridge deck roughness,and the comparative study is conducted Finally,the influence of vehicle speed,vehicle model,vehicle load,vehicle suspension system stiffness and bridge span on the response of vehicle bridge coupled vibration system are analyzed based on the measured bridge deck roughness and vehicle trajectory randomness.The results show that: under the condition of random vehicle trajectory,with the increase of vehicle speed,the bridge impact coefficient presents an increasing trend,but when the vehicle speed is large(V≥25 m/s)According to the statistics of 500 groups of bridge impact coefficients under the same speed and different vehicle trajectories,it is found that the value of bridge impact coefficient obeys normal distribution;based on the spatial bridge deck irregularity and vehicle random driving path,the bridge impact coefficient is greater than the bridge impact coefficient under the condition of fixed vehicle trajectory.When the vehicle speed is 25 m/s,the bridge impact coefficient is higher than that under the condition of fixed vehicle trajectory The maximum difference is 0.05(20%);at the same speed,with the deterioration of bridge deck condition,the bridge impact coefficient increases significantly,and the worse the bridge deck condition is,the more severe the bridge impact coefficient changes with the vehicle speed;the selection of different vehicle models has little influence on the bridge girder response in the vehicle bridge coupling system,and the complex vehicle model can obtain the response data of vehicle components With the increase of vehicle load,the mid span response of the bridge increases obviously;the change of vehicle suspension system stiffness has little effect on the bridge vibration response,but with the increase of vehicle suspension system stiffness,the displacement and acceleration response of vehicle body show a decreasing trend.By comparing the displacement impact coefficient of middle span and side span of three span continuous beam bridge under the condition of fixed vehicle trajectory and random vehicle trajectory,it can be found that the impact coefficient of mid span displacement of bridge is larger than that of fixed vehicle path,and the maximum deviation is 0.24(66.7%).The results of this paper can provide a reference for the dynamic performance evaluation of bridge structures.