Code Formulas for Ship-Impact Design of Bridges

Abstract

Four finite-element models of ships with deadweight tonnage varying from 3,000 to 50,000 t are developed for numerical collision simulation. The time histories of ship collisions against rigid walls are obtained using the software LS-DYNA. Equivalent static loading is determined, and simplified formulas are developed through a fitting procedure as indicated by the data from the numerical simulations. Codified formulations from AASHTO and other design specifications are compared with the simplified formulas. The geometric effects of the bridge foundation on the ship impact force are investigated with an example pile cap. A geometric modification factor is proposed for an ideal rectangular block to modify ship impact forces estimated by code formulas.