Date

2019

Document Type

Dissertation

Degree

Doctor of Philosophy

Department

Civil Engineering

First Adviser

Pamukcu, Sibel

Abstract

The main objective of this thesis is to examine systematically the proposed improved performance of finned piles over monopiles when subjected to lateral static and cyclic loading. In order to achieve this objective, both physical and numerical simulations were conducted on finned and monopile and outcomes were analyzed for design recommendations. The physical tests were performed on scaled model piles at 1:100 reductions of typical wind turbine monopile foundations.The cyclic lateral load tests were conducted on the scaled down foundation models at 1g condition. Cyclic tests were conducted to evaluate the long-term performance of the finned piles under cyclic wind loading conditions. Both the lateral and rotational responses of the foundation systems were evaluated at 1000 cycles of loading. The long-term performance at 107 cycles, defined as the fatigue limit state of the offshore wind turbine foundation, was derived from data fitting using power laws proposed by other researches. The results of both the static and cyclic lateral loading tests confirmed improved performance indicators of finned piles over monopiles. The major indicators were increased lateral capacity and decreased pile head rotation, both of which are important design and performance considerations of supported wind turbines, as the increase in lateral capacity translates into increase in factor of safety against excessive lateral pile head rotation.The laboratory lateral static test results were verified numerically using PLAXIS modeler. The physical and numerical simulation results were found to corroborate well, allowing to determine the optimum fin dimensions from numerical analysis.

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