Fatigue Performance Of Steel-composite Beams Based On Bridge Health Monitoring Data

Steel-concrete composite bridges have been widely used in bridge engineering in recent years because they can effectively play the advantages of two kinds of composite materials,have low construction difficulty and have good economic benefits.Compared with ordinary concrete girder bridges,steel-concrete composite girder bridges have the advantages of light weight and large span.Compared with steel bridges,steel-concrete composite girder bridges consume less steel,have stronger detail stability and flexural stiffness,and have higher ductility.However,under the repeated action of vehicle load for a long time in the operation of steel-concrete composite beams,various longitudinal and transverse welds are prone to fatigue damage or even fatigue damage.Therefore,it is very important to study the fatigue life of steel-concrete composite beams under vehicle load and the factors affecting the fatigue life.Based on the dynamic vehicle weighing data and dynamic strain monitoring data obtained from the bridge health monitoring system,this paper analyzes the fatigue life of the sixth league(55m)steel-concrete composite beam of The K20+198.9 Zaozhuang viaduct under the action of vehicle load.Statistical analysis based on the measurements of the WIM system,vehicle type,speed,traffic and other basic information,on the basis of further analysis of vehicle axle load,wheelbase,such as the key technical indicators,based on the linear fatigue damage cumulative rule,calculate the measurement model of the equivalent axle load and equivalent wheelbase,thus established the fatigue vehicle model based on the measured traffic.Compared with the fatigue vehicle models provided in the bridge codes of other countries,the fatigue vehicle models determined by the method in this paper are more consistent with the actual situation of monitoring.Using finite element analysis software ABAQUS to establish a solid bridge detail analysis model,determine the focus of the main fatigue details,using the established fatigue loading vehicle model,to establish the stress time history curve of fatigue details focus,in turn,the rain flow count method is adopted to establish the focus stress spectrum,in the name of the concerns of the fatigue life calculation of fatigue details.The empirical mode decomposition method was used to separate the vehicle load stress from the actual stress data collected by the health monitoring system.The vehicle load stress-time history curve was established,and then the daily stress spectrum of measured vehicle load stress was established to calculate the fatigue life of each fatigue detail concern.