Collision Tolerant Pile Structure Hinge Concepts

Abstract

Two Collision Tolerant Pile Structure (CTPS) design concepts were developed for the deployment of navigation aids in shallow water. The CTPS concept consists of the marker/light mounted on a single pile hinged just above the mud line. The hinge allows the pile to flex during a vessel/pile collision yet retains a restoring moment to return the pile to an upright position. The two designs presented here are a peripheral stay/central universal joint hinge concept and a central stay concept. For each design, a 4 m physical model was built for testing. Experiments included laboratory restoring moment-angle tests and in-water barge collision experiments and wave response measurements. Field experiments demonstrated that the pile sustains negligible damage during barge collisions, recovery is prompt, and pile motion in large waves is very small. Experiment results were compared with a 2-dimensional computer simulation of the pile dynamics with good agreement.