Ship Collision Analysis of a Floating Bridge in Ferry-Free E39 Project

The Norwegian Public Roads Administration is running a project ‘Ferry free coastal route E39’ which includes replacing ferry crossings by bridges or tunnels across eight fjords in Western Norway. Since most of the fjords are wide and deep, traditional fixed links are not possible to be constructed. Therefore, floating bridge and tunnel concepts are proposed for the fjord-crossing project. Because floating bridges and tunnels have many structural components close to the water surface, a critical concern of accidental ship collision loads is then raised. Considering the large displacement and high speed of the passing ships, the interactions between the bridge structure and the ship bow can be significant should collision occurs. It is therefore important to carefully evaluate bridge response subjected to ship collision loads in the design process. This paper presents a case study of ship collision analysis of the floating bridge concept for Bjørnafjorden. Two possible collision scenarios, i.e. ship-pontoon and ship-girder collisions, are considered. First, local structural deformation and damage are numerically investigated by detailed finite element models using LS-DYNA. Second, bridge global response under ship collision loads are simulated in USFOS. By combining the local and global analyses, a comprehensive overview of bridge response under ship collision load can be obtained.