In this paper, a computational study of the structural responses of a floating bridge for crossing of the Bjørnafjord in Norway is presented. The study employs an idealized floating bridge model developed based on the phase 3 design concept which comprises a very long, straight and side-anchored floating bridge. Due to the very long span and complex topology, the local wind waves exhibit some inhomogeneities. This study investigates the effects of inhomogeneous wave loads on the global responses of the floating bridge. The structural responses of both the bridge girders and the mooring lines are presented and discussed. In addition, the short-term fatigue damage induced by inhomogeneous wave loads in the mooring lines is also evaluated.
The Norwegian Public Road Authority (NPRA) initiated the E39 coastal highway project with the aim to significantly reduce the time for travel by road along the Norwegian coastline. The reduction in travel time will be mainly achieved by replacing time-consuming ferry trips across the fjords with road connections by means of bridges and/or tunnels. Owing to the fact that many fjords along the E39 highway route are very wide and deep, this brings challenges for constructing road connections across the fjord. For example, the combination of a span of up to 5 km and waters as deep as 500 m makes it very difficult for conventional bridges to cross the Bjørnafjord. Constructing floating bridges for this fjord crossing was soon identified as an appealing option because of their advantages of using natural buoyancy for load-carrying purposes and being less sensitive to seabed conditions as compared with other kinds of bottom-founded structures. Since then, many research activities related to the feasibility of floating bridge concepts across the Bjørnafjord have been carried out (Cheng et al., 2018a; Cheng et al., 2018b; Viuff et al., 2019; Xiang et al., 2018).