Impact Coefficient Analysis Of Simply Supported Beam Bridge Based On Vehicle-Jumping Condition

When the vehicle is driving on the bridge deck,due to the random or periodic irregularities of the bridge deck,the phenomenon of instantaneous separation and emptying of the wheels and the bridge deck is referred to herein as the phenomenon of "jumping".At present,most of the researches on vehicle-bridge coupling adopt the assumption that vehicles continue to drive closely.In this paper,the numerical simulation of vehicle-bridge coupling vibration under vehicle jump conditions is constructed based on transient dynamics analysis of ANSYS based on transient dynamics analysis of the bridge deck,and the variation law of impact coefficient under close adhesion and vehicle jump conditions is analyzed.Through orthogonal test,the sensitivity analysis of the main influencing parameters under two types of working conditions of single vehicle was carried out.Finally,based on the comparison between the actual bridge test data and the numerical simulation results,the necessity of considering the tripping conditions is analyzed when analyzing the vehicle-bridge coupling vibration problem.(1)Use the powerful finite element general software ANSYS to independently model the vehicle and the bridge.According to the vehicle model characteristics and the axle-to-bridge contact displacement coordination conditions,the interaction force between the axles and the axles at any time is solved,and the axle-bridge separation-fitting is fully considered The resulting discontinuous contact phenomenon establishes the discriminating condition of vehicle-bridge coupling tripping,and applies APDL programming language to the bridge and vehicle-related nodes at any time to realize the numerical solution of the vehicle-bridge coupling vibration problem.The applicability of this method under the conditions of uniform speed and uneven bridge surface was verified by comparison with the existing literature results and the actual bridge test.(2)Orthogonal test design is adopted to sensitize the mid-span deflection impact coefficient of 7 main influencing factors such as vehicle speed,vehicle quality,bridge span and bridge deck unevenness under 32 operating conditions analysis.According to the comparative analysis of the sensitivity of the orthogonal test,the sensitivity of the impact coefficient is different under the conditions of close adhesion and jumping.The influencing factors of bridge deck grade are the most sensitive,and the sensitivity of the jumping condition is increased by nearly one-half compared with the close-fitting condition.The bridge span factor is the second,and the sensitivity of the jumping condition is increased by nearly one third compared to the close-fitting condition.(3)Verify the accuracy of the trip model and the change of impact coefficient by comparing the results of the actual bridge test and numerical modeling.The change of bridge deck unevenness grade has a significant effect on the dynamic impact of bridge deflection.When the bridge is relatively flat,the difference between the impact coefficients of the two types of working conditions is not obvious.With the increase of the bridge deck grade,the impact effect under jump conditions There is a certain increase,and the impact coefficient is about 15% higher than the close-fitting condition,which is closer to the impact coefficient data detected by the real bridge.The impact of the vehicle-bridge coupling vibration problem should be analyzed on the impact of the trip condition.