Simple Dynamic Model for Fender Pile Analysis and Design

Abstract

Pier fender systems such as fender piling must be designed to absorb the impact energy of berthing vessels to avoid damage to either the vessel or pier structure. However, current analytical methods such as the kinetic energy approach do not consider the energy dissipated in the system during vessel impact. Energy dissipation has the effect of reducing the forces on the vessel and fender and therefore should be considered in design both to minimize overconservatism and to evaluate the relative performance of various types of fendering systems. This technical note presents a dynamic approach to the analysis of fender piles where the impacting vessel coupled with the fender pile is modeled as a freely vibrating, multidegree of freedom structure with lumped masses, stiffness, and damping. Field impact tests were conducted and compared to the new dynamic model with reasonable agreement. The new dynamic model was found to reduce the estimated forces on the pile by about 25% as compared to the kinetic energy method.