Suction caisson performance under monotonic and cyclic loading

Abstract

This work investigates the monotonic and cyclic behavior of monopod suction caisson foundations for offshore wind turbines, which primarily operate under lateral and moment loading. A key aspect in the design of these systems is the assessment of the permanent rotations experienced by the foundation due to the high number of loading cycles stemming from environmental forces (sea waves and wind), which in turn may compromise the functionality of the turbine. With focus on the case of caissons in sand, this work aims at discussing the results of three-dimensional finite element analyses carried out with the commercial code ABAQUS. To adequately reproduce the cyclic ratcheting of sand, the SANISAND-MS constitutive model is adopted. The numerical results highlight the role played by the eccentricity between the horizontal force and the external moment, the maximum moment applied, and the relative density of the sand on the foundation response, and provide insights on the soil-structure global and local interaction mechanisms.