Ship collision analysis on offshore wind turbine monopile foundations

It was shown that a slight variation of the impact velocity can lead to consequences ranging from minor damage of the OWT to collapse. Furthermore, the behaviour of the OWT during collision is highly sensitive to wind loads as it was shown that in some cases the OWT can collapse for an impact velocity of only 3 m/s and, in the worst case, can fall directly on the ship. The results obtained showed that it is important to account for the soil flexibility when performing collision simulations because considering the monopile as being clamped at the base would lead to an overestimation of the plastic deformation of the collided structure. Moreover, when the OWT is collided by a deformable striking ship, the deformations of the OWT are 2 times smaller comparing to the deformations caused by impact with a rigid ship and the structure can withstand collisions without collapsing with an impact velocity up to 6 m/s.