Structural control of the floating breakwaters by implementation of tuned liquid column damper

Abstract

The growing maritime activities have led offshore engineers to the application of floating breakwaters to protect coastlines from erosion and to provide a layer of support to ports in the case of strong wave actions. In these applications, minimizing the floating part responses to wave-induced excitations as one of the most critical operational characteristics would be a key factor. In this article, the structural responses of the floating breakwaters are studied through modeling and simulation. To mitigate the floating part wave-induced vibrations, an attached tuned liquid column damper is integrated into the simulation. In the first stage, the numerical model of the floating breakwater system containing the floating body and the mooring system is created. Then, by proposing an iterative coupling procedure, the joint tuned liquid column damper-floating breakwater model is developed. Several rigorous study cases are defined to evaluate the effect of tuned liquid column damper on controlling the floating body unwanted vibrations. In this application, the Airy wave theory and the Joint North Sea Wave Observation Project wave spectrum are used for wave excitations. In order to evaluate the effect of tuned liquid column damper on floating breakwaters, some design parameters like floating body motions and mooring system-mobilized tensile stresses are evaluated. The simulations are conducted in both the time domain and the frequency domain for cases with and without tuned liquid column damper. The rain flow counting method is applied to perform the mooring system fatigue analysis. The study results clearly proved that implementation of tuned liquid column damper would mitigate the floating body responses compared to the original floating breakwater system. In addition, it is indicated that the fatigue-induced failure risks in tuned liquid column damper-floating breakwater mooring system is decreased that would reduce the procurement costs and increase the operational safety of the floating breakwater system.