Effects of Floating Wave Barriers with Square Cross Sections on the Wave-induced Forces Exerted to an Offshore Jacket Structure

The jacket-type platform is the most common offshore structure employed for the oil and gas production from the reservoirs below the seabed. It consists of three main parts: superstructure or topside, substructure or jacket, and the foundation or piles. Construction of floating breakwaters and wave barriers is one of the commonly used methods for the protection of harbors and coastal structures. However, their application for the protection of offshore structures has not been extensively studied. The present paper investigates the effects of a floating wave barrier installed in front of an offshore jacket structure on the wave height, wave-induced forces, and consequently jacket’s base shear and overturning moment.Abul-Azm and Gesraha (2000) studied the hydrodynamics of floating pontoons under oblique waves. Gesraha (2006) analyzed the shaped floating breakwater in oblique waves. Rahman et al. (2006) presented a numerical modeling for the estimation of dynamic responses and mooring forces of submerged floating breakwaters. Christensen et al. (2018) conducted a set of experimental and numerical studies on floating breakwaters. Dong et al. (2008) carried out a number of experiments on the wave transmission coefficients of floating breakwaters.In the present research, a jacket model with the height of 4.55m was fabricated and tested in wave flume of NIMALA marine laboratory. The wave flume was 402m long. The jacket was tested at the water depth of 4m subjected to JONSWAP waves with the height of 20cm, 23cm, and 28cm. The mechanism of wave energy dissipation due to hitting a wave barrier is mainly a combination of the wave diffraction and the wave reflection. A square cross section was selected for the wave barrier. Results showed that a floating wave barrier can effectively reduce the base shear and overturning moment in an offshore jacket structure.