Ship collisions with pile-supported structures-estimates of strength and ductility requirements

This paper describes an analytical approach for design of p ile-supported structures subjected to ship collisions. The main problem being addressed is how deformation of both ship and structure, in a simple way, can be taken into account when determining the collision force. Such an approach will lead to more accurate calculations of the maximum collision force as compared to methods, which assume the impact energy to be absorbed solely by ship deformations. The approach described here requires knowledge about the load-deformation characteristics of the structure and the ship. A major challenge in this context is to establish the so-called load-i ndentation curves for ships. The paper demonstrates a principle to establish load-i ndentation curves, which, in a mechanically consistent way, are linked to the Eurocode collision force formula. The obtained loadindentation curves have been used to develop analytical criteria for strength and ductility assessment of pile- supported structures. Calculations based on the outlined approach show that the maximum collision force reduces significantly as compared to calculations, where the deformation capacity of the structure is disregarded. The reduction of the maximum collision force can be transformed into similar reduction of the required number of piles.