Structural Performance of Breasting Dolphin Under Berthing Load Variations

Abstract

Breasting dolphins are critical marine structures that transfer vessel impact loads to the jetty system during berthing operations. In several existing terminals, increasing operational demands may necessitate the accommodation of vessels larger than the original design vessel, provided that water depth and terminal functionality permit such operation. However, operational feasibility cannot be evaluated solely based on navigational clearance, as berthing velocity, fender reaction, pile stiffness, and soil–pile interaction may significantly influence structural demand. This study investigates the structural performance of an existing breasting dolphin at an oil and gas shore-base jetty under varying berthing load conditions. Four vessel capacities, namely 7,000, 8,000, 9,000, and 10,000 DWT, and five berthing velocity conditions were assessed using a three-dimensional structural model. Additional permanent loads, fender and bollard loads, and soil support modeled using spring element were included. Structural acceptability was assessed based on the occurrence of plastic member behavior and axial force–biaxial bending interaction criteria. The results indicate that only two scenarios remained fully elastic: 7,000 DWT at 0.108 m/s and 8,000 DWT at 0.103 m/s. All other applicable scenarios exhibited plastic member behavior, with critical interaction utilization under difficult sheltered berthing ranging from 3.392 to 3.706. These findings highlight that operational approval for larger vessels should be controlled by berthing velocity and verified structural capacity, rather than by water depth alone.