Fatigue Reliability Analysis Of Steel Bridge Welding Details Based On Random Traffic Flow

The steel bridge has many welded parts,and the reliability of the welding details directly affects the overall life and safety performance of the steel bridge.Therefore,the fatigue reliability analysis of steel bridge welding details has been a hot issue in academic research at home and abroad in recent years With the development of the economy,the traffic volume has increased greatly,and the axle load of the vehicle has been continuously improved,so that the bridge is under the cyclic load of the traffic flow for a long time.Therefore,the fatigue performance of the bridge welding details will be greatly increased with the increase of the traffic flow.Impact.This paper will analyze the fatigue damage of the welding details of a large cable-stayed bridge in China based on the measured traffic data,and evaluate the service life of the bridge according to its reliability.The main work and research results of this paper are as follows:1.According to the WIM system of the bridge,the basic parameters data of the vehicle is obtained,such as vehicle type,trafic flow,lane allocation,vehicle speed and vehicle weight,the distribution law and distribution type of these parameters are obtained by probability and statistics methods.Using the MATLAB programming language to generate a random traffic flow program based on the above statistical results to simulate the actual traffic conditions.2.Using ANSYS software to establish the finite element model of the bridge,verify the correctness of the model according to the calculation results and theoretical analysis,select the more details at the most unfavorable load position,and adopted MATLAB to fit the influence surface,then analyzed them.The influence surfaces of the typical U-rib-top weld and U-rib weld are obtained and compared.The random traffic flow program is loaded onto the influence surface to obtain two kinds of details of the stress time history curve,and the equivalent stress and stress cycle times are extracted by the rain flow counting method.3.Carry out detailed comparative analysis of the normative fatigue strength curves at home and abroad,and use the fatigue strength curve in European norms to establish the calculation method of cumulative fatigue damage of welding details,and predict and compare the U rib-top plate weld and U rib.Fatigue life of two types of weld details for butt welds.The reliability of welding detail of Dongping River Bridge is studied,and the fatigue limit function with trafic load growth is established.The influence of traffic load growth on fatigue reliability at welding detail is analyzed.It is evaluated according to the target reliability function.Fatigue performance at the welding detail of the DongPing River Bridge.Feasibility advice was put forward for the safe use and maintenance of steel bridges.