Vehicle models for fatigue loading on steel box-girder bridges based on weigh-in-motion data

On the basis of massive data collected by the Weigh-in-motion (WIM) system of XiHouMen Bridge, analysis of fatigue-loaded vehicle models and theoretical fatigue life of U ribs butt weld of steel box girder are discussed in this paper. Firstly, basic vehicle information can be obtained from preliminary statistics of various types of vehicles data and the vehicles passing XiHouMen Bridge are divided into seven types based on the number of axles and axle groups. Secondly, the statistical distribution functions of gross vehicle weight under different loading conditions and wheelbase for each type of vehicle are developed to obtain the equivalent fatigue vehicle load. Then, the parameters of various types of fatigue-loaded vehicles are determined by combining the mathematic expectation of gross vehicle weight distribution with Palmgren-Miner fatigue damage accumulation theory. Finally, the seven types of fatigue-loaded vehicles are applied to the component-coupled finite element model of the steel box girders in XiHouMen Bridge and the theoretical fatigue life of the U ribs butt weld can be estimated. This research provides a reference to define the vehicle models for fatigue loading on steel box-girder bridges based on WIM data.