Time-varying Characteristics of Bending Deformation for Bridge under the Action of Moving Vehicle Loads

Abstract

This paper takes the three-span bridge under the two vehicles moving along opposite directions as an example. By using the Singular Function to list the moment equation of the whole bridge, the integral rule of Singular Function and the force, and displacement boundary conditions, the deflection equation of bridge under corresponding vehicles is deduced. Furthermore, the deflection curve of the bridge at each time under the action of one vehicle, dual-vehicles and multi-vehicles moving along the forward direction and reverse motion is obtained by using Mathcad software. Comparing the influence of different vehicle speeds and shifting direction on the bending moment and deflection regularity of bridge’s each section, the relative position relationship between the cross section and the vehicle is studied when the deflection of each section is maximized during the vehicle movement. With the increase of vehicle speed, the maximum value of section deflection increases first and then decreases. When the vehicle is moving along opposite direction, the distance between the section and the vehicle decreases first and then increases with the movement of the vehicle when the deflection of each section reaches the maximum. When the vehicle is moving in the same direction, no matter the vehicle is approaching or crossing the cross section, the deflection of the section reaches the maximum, and the distance between the section and the vehicle is very small. To the middle section of the bridge, the distance increases rapidly, and then the distance between the cross-section and the vehicle linearly reduced trend.