A performance-based approach for the design of coupled dolphin-fender berthing structures

The paper presents a performance-based approach for the design of flexible breasting dolphins equipped with marine fenders, often used in jetties belonging to offshore oil terminals. Since the distance of the breasting system to the mooring one and to the oil terminal is generally limited for serviceable and operational issues, the proposed design methodology, based on the kinetic energy approach, assumes a predetermined displacement for the dolphin, as well as a desired performance of the fender, and allows evaluating the stiffness of the flexible system required to achieve the desired energy absorption capacity. The design procedure accounts for the dolphin-fender interaction, as well as for the soil-embedded dolphin interaction, and it is specialised considering the common technical solutions adopted in the design of breasting dolphins. The approach is applied to a hypothetical case study consisting of a new berthing structure for a coastal terminal located on the Middle Adriatic Sea, in Italy, presenting non-ideal conditions for the installation of flexible dolphins. Applications demonstrate the effectiveness of the proposed approach and the role of the dolphin-fender interaction in withstanding the berthing actions, making it possible to design a flexible berthing structure also in the case of relatively shallow water depths.