Analysis and Design of Ship Collision Barriers on a Submerged Floating Tunnel subjected to Large Ship Collisions
MetadataVis full innførsel
- Institutt for marin teknikk 
Reinertsen AS is developing a bridge crossing concept to cross the Sognefjord in Norway. The concept consists of floating bridge and submerged tunnel. The submerged tunnel is exposed to ship collisions from passing ship traffic. A protective ship collision barrier is used to protect the exposed part of the submerged tunnel. A design of the collision barrier is proposed. The barrier is made of Aluminium. There are some special considerations one must take into account when using aluminium. Aluminium that is heat treated has a reduction in strength, referred to as the reduction in heat affected zone. Different alloys react differently to heat treatments. Some have a large reduction in HAZ, while some are not affected at all. Two alloys are used and studied in this thesis. Alloy 5083 with temper O and H12, and Alloy 6082 with temper T6. A Ramberg-Osgood material description is used to describe the material properties of Aluminium alloys in the Finite element analysis. A failure criterion is used based on design principles found in Eurocode 9. The failure criteria are only depending on yield stress of the alloy, which gives reason to doubt the goodness of the criteria when strain failure for an aluminium alloy depends on many other factors. An analysis of a stiffened panel subjected to lateral and axial loading is done. The loading is in the form of a rigid sphere and rigid plate, moving with a constant velocity trough the plate. A comparison between the use of alloy 5083 O and alloy 5083 H12 is carried out. The effect of heat affected zone is also studied. The analysis showed that the impact stresses dominate more than the reduction in the HAZ regarding strain localisation and fracture pattern. There is a reduction in the resistance force capacity because of HAZ, both in axial and lateral direction. A collision analysis of a model of a bow and barrier is carried out. The design of the ship model is based on the cruise ship MS Balmoral. The barrier design is based on local and global strength considerations. The barrier is modelled as a straight rectangular cylinder, with clamped ends. A collision analysis using LSDYNA is carried out. The analysis consists of sending the bow trough the collision barrier. The analysis showed that the design of the barrier must be strengthened. The bow does receive little damage, and the barrier is too weak to protect the tunnel. A model of the bridge concept is made in USFOS, with the intension to carry out a global collision -response analysis. This was not finished, due to time limitations.