Study On Bending Deformation And Dynamic Characteristics Of Multi Span Bridges Under Different Vehicular Conditions

With the continuous development of social economy and the improvement of infrastructure and transportation system in China,health testing and safety assessment of bridges have increasingly become the focus of social concern.Research on deformation and vibration characteristics of bridge under moving vehicle loads under different working conditions is a basic subject of bridge health monitoring.In this paper,the deformation and vibration characteristics of multi-span bridges under several typical working conditions,such as uniform driving,braking and sports car,are studied through theoretical,field testing and numerical simulation.The main research contents and results are as follows:(1)Taking a three-span bridge under two vehicle loads moving along opposite direction as an example,the moment equation and deflection equation of the bridge under the corresponding vehicle loads are deduced by using the singular function and its differential-integral principle.Furthermore,the deflection curves of single-vehicle,double-vehicle and multi-vehicle moving along the bridge in one-way and two-way directions are obtained.The influence of different vehicle speed on the time-varying law of bending moment and deflection of each section of the bridge is compared,and the relative position relationship between the section and multiple vehicle loads is obtained when the deflection of each section reaches its maximum.(2)Taking Yuquan Bridge of Jiangsu Normal University as a prototype,the finite element model is established in Ansys software after simplification.The stress and deformation characteristics of the bridge under moving vehicle loads are simulated by applying load steps.The influence of vehicle speed on the maximum stress and deformation of the bridge is analyzed.(3)Through the test macro TST3828 EN and TST5926 EV,based on environmental incentives,the fundamental frequencies of the Xuzhou Peace Bridge are determined,and the first two order natural frequencies,damping and vibration patterns of the bridge are also determined.Through the running car test and brake test under different speed,the maximum and minimum dynamic deformation of the bridge is measured by using TST5925 EV wireless telemetry dynamic strain measurement and analysis system.Using the relationship between the dynamic amplification coefficient and the impact coefficient,the impact coefficient of the bridge is calculated.(4)Based on the beam transverse vibration theory,the singular function is used to establish the vibration response equation of the single-span bridge under the action of vehicles,and the Mathcad software is used to obtain the displacement and acceleration response curves of bridge vibration.Taking Yuquan Bridge with two lanes in campus as the test object,the acceleration response of the bridge in each test was collected by the wireless telemetry dynamic strain test and analysis system,and the influence of vehicle working conditions and vehicle speed on the peak acceleration of each section of the bridge was analyzed.There are 72 papers,21 tables and 81 references.