Local and global responses of a floating bridge under ship-girder collisions

Abstract

The Norwegian Public Roads Administration is running a project “Ferry Free Coastal Route E39” to replace existing ferry crossings by bridges across eight fjords in western Norway. Since most of the fjords are wide and deep, construction of traditional bridges with fixed foundations is not possible. Therefore, floating bridge concepts are proposed for the fjord-crossing project. Since the floating foundations of the bridges are close to the water surface, the concern of accidental ship collisions is raised. Considering the displacement and speed of the passing ships and the significant compliance of the bridge, interaction between the bridge and the ship can be significant should a collision occur. Many studies have been conducted on ship collision with bridge structures with a special focus on bridge piers. However, the research on ship collision with bridge girders is quite limited. The purpose of this study is to investigate the collision response of a floating bridge for ship–girder collision events. Both the local structural damage and the global dynamic response of the bridge are assessed. Local structural deformation and damage are first investigated by numerical simulations with detailed finite element (FE) models in ls-dyna. Subsequently, the bridge global response to the collision loads is analyzed in usfos using the force–deformation curves from the local analysis. By combining the local and global analysis results, a comprehensive overview of the bridge response during ship–girder collisions can be obtained.