Study on dynamic impact factor of girder bridges due to vehicle load model

Abstract

Abstract The dynamic effects of moving vehicle on bridge are generally treated as withstand static loads that are recommended an increment by dynamic impact factors (IMs) (or dynamic amplification factors) in many design codes, that are a function of either the span or the first flexural natural frequency of the bridge. The value of the IM will relate to safe and economical in new bridge designs, evaluate recommendation and operation of bridges. Due to the bridge-vehicle interaction model, previous studies have shown that the calculated IM from field measurements could be higher than the values specified in design codes. Currently, studies on IM often focus on using interaction models with multi mass vehicles move on bridge that are increasingly similar to real models. This study develops a 2D three-axle vehicle–bridge model to analysis the dynamic response of the girder bridge subjected to moving loads consider to some vehicle parameters with the each axle is modelled in two masses, each mass is connected to a spring and a damping corresponding to the suspension and tire. In addition, depending on the stiffness parameters of the suspension and tires of the analyzed vehicle model, the IM results of this study are different from those of some authors and the bridge design rules. Based on the dynamic analysis of the bridge under the vehicle loading consider the stiffness of tire and suspensions, the calculation of the IM needs to be considered more carefully in the process of designing new bridges or existing bridges.