Recently it is required to consider the wave impact load for the structural assessment of FPSO appurtenance. The importance of the wave impact load in the deep sea was increased after the casualty of the structure by the wave impact has been reported in FPSO installed in the North Sea. The wave impact load is not easy to estimate because the wave impact pressure has the uncertainty in the peak pressure, the wave celerity, the impact area and the wave breaking location relative to target structures. In this study, the experiments with the modulated wave train for wave breaking were performed to investigate the characteristics of the wave impact load on the circular cylinder typically representing the appurtenance of FPSO. The design guidance with the parameters both the celerity of the breaking wave and the impact zone was proposed for applying the wave impact load on the design step of the appurtenance.
Recently the structural assessment on the appurtenance of FPSO considering the wave impact load is required. The importance of the wave impact load in the deep sea was increased after the casualty of the structure by the wave impact has been reported in FPSO installed in the North Sea (Bas Buchner et al., 2004). According to the precedent study, it is possible that the plunging wave breaking occurs in the deep sea (Hong and Shin, 2007) and this plunging wave breaking could cause the wave impact on the structure(Xu et al., 2008; Xu et al., 2008). Therefore the wave impact load needs to consider in the structural design. Generally, to apply the wave load as the quasi-static term with Morison equation is the approach for the design of the appurtenances like the riser, caisson and sea-fastening connected in the side shell of FPSO.
