Design of stone-filled base-reinforced concrete caisson type multi-cell composite breakwaters

Breakwaters are structures with functional properties designed with different construction purposes, consisting of stone, concrete, reinforced concrete, and steel structural elements built in the marine time environmental loads. Wave and current loads are the most influential factors in breakwater design. Built on weak seabed, breakwaters constructed to withstand hydraulic and hydrodynamic loads. Geotechnical analysis required to carry their structural weights. Sometimes designed as weight type with single-multiple concreate blocks, sometimes as concrete or single-multi-cell reinforced concreate structures on a stone filled base. In this study, the stability, curtain-based structural analysis, and reinforcement design of composite multi-cell reinforced concrete caissons type breakwaters have been conducted. Firstly, the location and dimensions of the breakwaters were determined. Stability analysis (sliding, overturning, soil bearing capacity) against wave and included hydrodynamic pressures was conducted. In the calculation of hydrodynamics pressures, the GODA Method, which considers the conditions of unbroken and breaking irregular waves, utilized. The lateral pressures of the fill soil in the multi-cell caisson structures calculated using the Rankine Method. The stone foundation sizing recommended by CERC (Coastal Engineering Research Center) used for sizing according to wave loads. In the structural analysis of the multi-cell caisson structure, both horizontal and vertical strip method used. In the horizontal strip method, the caisson divided into segments at certain intervals with horizontal planes and structural analysis performed for each segment using the CROSS moment balancing method based on the internal and external loads acting on each segment. The section effects of the frame elements inside each segment and therefore, the horizontal reinforcement design calculated. In the vertical strip method, a curtain-type solution adopted, considering the multiple strips to be considered, such as internal and external strips and span-support strips. The vertical reinforcement of the curtains was designed. Instead of calculating stirrups for transverse reinforcement, the calculation reinforcements from the horizontal strip method used. As a result, the stone foundation size, concrete volume, and reinforcement weight of the caisson cell calculated based on the structural analysis. Gusseted connections commonly used in submerged water tanks, reinforcement details and the caisson shoe also preferred and improved in the design constructively in the study. Keywords: Caisson type breakwater, Retaining wall, GODA Method