Dynamic responses of a floating bridge subjected to ship collision load on bridge girders

Abstract

The Norwegian Public Roads Administration is running a “Ferry free coastal route E39” project to install bridges or tunnels across fjords in Western Norway. A floating bridge concept is proposed for the fjord-crossing project in Bjørnafjorden. One of the key aspects in design is to ensure bridge safety under accidental ship collision loads. The objective of this paper is to study the dynamic behaviour of the floating bridge subjected to ship collision loads on bridge girders. Numerical models of the ship-bridge collision system are developed using the dynamic analysis software USFOS. The curved floating bridge is modelled by beam elements and the striking ship is represented by a nodal mass-nonlinear spring system. Numerical analyses of ship collision with a bridge girder are carried out for three impact locations, i.e. middle spam, a span in quarter position and at the end span of the bridge. Bridge responses including the displacement, axial and shear forces and bending moment are calculated. Results show that the floating bridge can endure the proposed ship collision energy of 250 MJ.