Dolphins

General

Dolphins are required in waterways and ports for various tasks: as berthing or mooring dol-phins. Their various functions require an analysis of different actions. Berthing dolphins must be designed for the impact of ships, mooring dolphins are subjected to the pull of mooring lines, wind loads and hydrodynamic pressures.

Dolphins can consist of single piles or groups of piles, the latter usually being met with in the form of lightweight timber piles in old structures. In the form of single piles, steel tubes or compound sections assembled from sheet piles, e.g. LARSSEN steel sheet piles, are to be recommended.

Loads

The critical design loads for dolphins result from the impact of ships during berthing manoeu-vres or the pull on the mooring lines of ships. The latter effect is made up of ship movements due to currents, wind, waves or ice. Berthing dolphins are designed for the ship impact loading case with a force FS,k such that the berthing energy can be converted into deformation work in the dolphin. The energy absorption capacity Ak,exist of a dolphin is calculated from the ship impact force FS and the horizontal de flection f of the dolphin at the level of application of the force:

Ak,exist =1/2 · FS,k · f

The available energy absorption capacity Ak,exist of a dolphin should be selected such that it is greater than or equal to the required energy absorption capacity A. The required energy absorption capacity A describes the component of the kinetic energy of the ship that must be absorbed by the dolphin. This is calculated using the mass, length, speed, turning speed and displacement of the ship, the spacing of the dolphins and the clearance under the keel. An exact description of how to calculate the required energy absorption capacity can be found in EAU 2004 section 13.3.

Subjected to the critical impact action FS , the design value of the steel stresses may not exceedthe yield strength fy in the case of berthing dolphins. For mooring dolphins, the design value of the steel stresses due to line pull, wind loads and water pressure may be equal to the maximum steel stress fu.

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