Analysis of a Monopile under Two-Way Cyclic Loading

A large diameter monopiles are commonly used as an offshore wind turbine (OWT) foundation to withstand lateral cyclic loads due to wind and wave action. In the present study, a two-dimensional finite element analysis was performed to evaluate the behavior of a monopile under two-way lateral cyclic loading. The centrifuge test carried out on a 0.7m diameter pile was being used to validate the constituent model. The parametric study was carried out on a monopile by varying the slenderness ratio (L/D = 4, 5, and 6) and load amplitudes (30%, 40%, and 50% of the ultimate pile capacity). From the load-displacement response of a monopile, it was observed that the measured accumulated displacement increases drastically for the first load cycle. For a given embedded length, the lateral displacement was observed to increase with an increase in load amplitude. For an embedded length of L/D = 4, the increase in load amplitude from 30% - 40% resulted in an increase in lateral displacement to 24%.