Dynamic response of dolos armor units to pendulum impact loads

Abstract

Design methods for concrete armor units have come under scrutiny because of several recent breakwater failures. The catastrophic failure of the Sines breakwater in Portugal and other less spectacular failures such as the one at Cresent City, California have kindled doubts as to the structural integrity of the large dolos concrete armor unit. A major difficulty encountered in rationally designing dolosse (or any other armor unit) is the specification of the loads. The complexity of the in situ loading conditions preclude an exact solution. Therefore, the pendulum test was developed to simulate the impact of broken units that are thrown around by the waves. This paper summarizes the results of a comprehensive numerical analysis to determine the states of stress in dolosse, with varying dimensions and concrete properties, subject to pendulum impact loads. A three-dimensional finite element method (FEM) analysis of pendulum impact tests was conducted through implementation of the ADINA finite element computer programs. The results of the FEM analyses are used to develop an analytical procedure which accurately predicts the peak tensile stresses in the shank and fluke of dolosse subject to pendulum impacts.