Quantitative consideration in selection of breakwater concrete armor unit based on unit’s internal tensile stress response

Abstract

Concrete armor units are essential for the protection of rubble mound breakwaters, yet their selection is generally not based on structural integrity considerations. In this study, the authors used static finite element simulations, as implemented by Ansys software, to compare the structural integrity of five armor units: Accropode, A-Jack, BPPT-Lock, tetrapod, and dolos. All armor units have a mass of around 11,500 kg and have the same quality of concrete at f’c of 30 MPa. The study involves two different loading cases: Armor units were (1) arranged on a breakwater slope subjected to their own weight and (2) placed on a horizontal ground subjected to idealized wave attacks. In Case #1, the armor units were modelled fixed to the ground and bonded to each other. In Case #2, the wave attack was modelled as a unidirectional and uniform pressure. From the simulation results, the authors compare the highest tensile stresses which could be found on the corner regions of the armor units—their most vulnerable region. In both cases, armor units with stocky shapes experience lower tensile stresses compared to those with slender shapes. These results confirm that Accropode, BPPT-Lock, and tetrapod are structurally safer than dolos and A-Jack.