Performance-Based Design of Perforated-Wall Caisson Breakwaters

Abstract

In this study, the performance-based design method developed for a conventional solid-wall caisson breakwater is extended to a perforated-wall caisson breakwater. First, to verify the mathematical model to calculate the sliding distance of a perforated-wall caisson, hydraulic experiment is conducted. A good agreement is shown between the model and experimental results. The developed performance-based design method is then compared with the conventional deterministic method in different water depths. Both the expected sliding distance and the exceedance percentage of total sliding distance during the structure lifetime decrease shorewards outside the surf zone, but they increase again toward the shore inside the surf zone. The performance-based design method is either more economical or less economical than the deterministic method depending on which design criterion is used. If the criterion for expected sliding distance or exceedance percentage is used in the ultimate limit state, the former method is less economical than the latter outside the surf zone, whereas the two methods are equally economical inside the surf zone. However, if the breakwater is designed to satisfy the criterion for exceedance percentage in the repairable limit state, the former method is more economical than the latter in all water depths.