Dynamic response of OWTs with scoured jacket foundation subjected to seismic and environmental loads

Tetrapod piled jacket (TPJ) foundations have been widely employed to support offshore wind turbines (OWTs). However, under the influence of environmental loads and wave-current-induced scouring phenomenon, there remains a notable research deficiency concerning the seismic response of TPJ supported OWT system. In these earthquake-prone areas, TPJ-supported OWT may encounter excessive overturning deformations and dynamic responses during its service life. To fill the gap in the current seismic design codes for TPJ foundations, this study comprehensively analyzed the seismic response of the TPJ system subjected to stochastic environmental loads at scoured sites, considering several potential influencing factors, such as the scour depth, soil strength, seismic frequency content and intensity. It is found that the high-stiffness steel framework of the TPJ system demonstrates a robust ability to withstand the lateral responses of acceleration and deformation. The development of scour depth alters the failure location of the TPJ structure and the pile-soil interaction mechanism, leading to an expansion in the acceleration and bending moment response, and an uplift trend in the pile foundation. Although higher soil strength improves the resistance of the TPJ system to vertical and horizontal deformations, it also amplifies the acceleration and bending moment responses of the TPJ system. Notably, the bending moments are greater in the leeward piles compared to the windward piles, necessitating additional protective measures in the design. These findings offer valuable insights into the seismic response of TPJ-supported OWTs in complex paralic environments.