Damage Analysis of Box Girder Based on a Vehicle-Bridge Interaction System

This study proposes a stress analysis method of reinforced concrete (RC) box girder based on damage to reveal the dynamic mechanical response and damage mechanisms of a bridge under moving vehicle load. The effect of different vehicle mass, speed, concrete strength, and longitudinal reinforcement ratio on the stress of a single box girder is investigated using solid finite element vehicle-bridge interaction dynamic elastic-plastic analysis (a total of 13 kinds of loading schemes) that is based on the Newmark algorithms of a numerical analysis model of a five-axle vehicle and road roughness. The results reveal that the damage status of the RC box girder strongly depends on the vehicle mass and speed. The damage region of the box girder gradually increases, and changes from flexural damage to flexural-shear damage, which fails rapidly as the vehicle mass increases from 10 t to 60 t. With an increase in vehicle speed, the maximum vertical vibration displacement and the maximum longitudinal stress of the steel bar increase nonlinearly and the damage of the box girder first increases and then decreases. The most severe damage occurs at the vehicle speed of 25 m/s for all vehicle masses. As a result, limiting speed below 25 m/s under the vehicle mass (10 t to 60 t) and increasing concrete strength and reinforcement ratio in a certain range could reduce the damage status of a bridge effectively.