Numerical Analysis of Serviceability of the Damaged Offshore Wind Turbine Jacket Foundation Subjected to Ship Collision

The serviceability of support structures is significantly threatened by the increase in unintentional ship-offshore wind turbine (OWT) collisions brought on by the vast installations of OWT than ever before. Referring to a collision accident between a ship and OWT in the South China Sea and its repair project case, this paper develops numerical models of the OWT jacket foundation in various conditions (i.e. undamaged, damaged, and reinforced). The lateral bearing capacity of the damaged jacket foundation in different loading directions was evaluated. The member strength and overall dynamic characteristics of the impacted jacket foundation in different conditions were compared and analyzed. The results indicate that when the ultimate load is reached, copious members and tubular joints of the damaged jacket foundation fail, resulting in the structure collapsing. The local strength and stiffness of the jacket foundation are weakened by the dent caused by the ship impact, and the stress concentration is formed at the damaged area. The stress level at the damaged member is dramatically reduced when the strengthening measures have been applied, and the structure's natural frequencies are significantly altered. The study can shed light on the evaluation of serviceability and the retrofit plan of damaged OWT foundations.