OasisLMS

Wind energy is one of the renewable energy resources in current situation for sustainable development. In wind energy sector optimization of overall design of wind turbine structure and foundation is very important to avoid high cost of wind turbine manufacturing and installation. Monopile foundation is the most popular among all the offshore foundation system to support offshore wind turbine. The behavior of offshore monopile foundations under cyclic lateral load in sand is studied in three-dimensional finite element analysis capturing the nonlinear response of soil and its stiffness degradation under cyclic loading considering Hardening Soil model with small-strain stiffness (HS-small). A series of monopile models are analyzed in Plaxis 3D software varying unitless aspect ratio (the ratio of monopile embedment depth L to monopile diameter D, L/D ranges between 2 to 12), and the lateral load eccentricity ratio (ratio of lateral load eccentricity e to monopile diameter D, e/D ranges between 1 to 6). The influence of these two parameters is studied to understand how the lateral displacement, rotation, lateral, and rotation-al load-transfer stiffnesses vary under cyclic loading considering monopile-soil interactions based on Coulomb’s friction law. It is observed that the aspect ratio of monopile is more influential than the lateral load eccentricity ratio to control horizontal displacement and rotation of monopile under lateral cyclic loading. With the increase in the aspect ratio of monopile lateral displacement and rotation decrease exponentially. The normal and shear stresses along the monopile shaft and at monopile base increase with a decrease in aspect ratio and increase in lateral load eccentricity. This study will be helpful to understand the lateral load-transfer response of monopile under cyclic loading which will be utilized for monopile design optimization.

Priyanka Bhartiya, Cowi India Ltd.; Tanusree Chakraborty, IIT | Delhi; Dimpanjan Basu, University of Waterloo; Martin Achmus, Leibniz University of Hannover

International Conference Proceedings