Effects of rail joints and train's critical speed on the dynamic behavior of bridges

The dynamic amplification of the railway bridges caused by the passage of a train varies according to several factors. Among these factors: defaults of roughness of the rail and its joints, etc. These defects are usually encountered in railways and they influence the dynamics of the vehicle-bridge interaction, whence the importance of this study. In this paper, the defect of rail joint is investigated with train's critical speed. The joints between the rails are modeled by periodic irregularities. The bridge is modeled by a simply supported uniform beam. The train is modeled as a convoy of vehicles moving with a constant speed. The governing equations of motion for the bridge-train interaction system are derived using the Lagrangian formulation and the modal superposition technique. These equations are integrated numerically by applying the Newmark method. This paper presents a computation code in FORTRAN to analyze the effect of the above-mentioned defects on the bridge's dynamic response.