Study of the Bearing Capacity of Stiffened Tall Offshore Wind Turbine Towers during the Erection Phase

Abstract

Offshore wind energy is a rapidly maturing renewable energy technology that is poised to play an important role in future energy systems. The respective advances refer among others to the monopile foundation that is frequently used to support wind turbines in the marine environment. In the present research paper, the structural response of tall wind energy converters with various stiffening schemes is studied during the erection phase as the latter are manufactured in modules that are assembled in situ. Rings, vertical stiffeners, T-shaped stiffeners and orthogonal stiffeners are considered efficient stiffening schemes to strengthen the tower structures. The loading bearing capacity of offshore monopile wind turbine towers with the four types of stiffeners were modeled numerically by means of finite elements. Applying a nonlinear buckling analysis, the ultimate bearing capacity of wind turbine towers with four standard stiffening schemes were compared in order to obtain the optimum stiffening option.

Fatigue life analysis of offshore wind turbine tower under combined action of wind and wave

“…Considering that the construction and operation costs of offshore wind turbines are higher than those of onshore wind turbines, it has become a trend to develop ultra-large power offshore wind turbines. Offshore wind turbine tower is subject to the combined action of wind load and wave load at the same time, and the stress situation is more complicated than that of onshore wind turbine, so it is necessary to calculate the environmental load in detail [1][2] and carry out the design technology research of the tower to improve its working performance [3][4][5]. In addition, the operation and maintenance cost of offshore wind turbine is higher than that of onshore wind turbine.…”

“…The research on fatigue life of offshore wind turbines has become a hot topic. Literature [1] studies the calculation method of fatigue life of single pile tower. Firstly, fatigue damage brought by wind load and wave load is calculated respectively.…”

“…In formula (1), N --the number of cycles expected to be generated under the stress range   ;   the lg N axis; lg lg 2s  =− ,  --The constant associated with the mean of S-N curves, s --The standard deviation of lg N . The S-N curve of Q345E material in air and sea water was extracted by referring to DNV-RP-C203 code "Recommended Practices for Fatigue Analysis of Steel Structures at Sea".…”

Accuracy of the Gamma Re-Theta Transition Model for Simulating the DU-91-W2-250 Airfoil at High Reynolds Numbers

“…Offshore wind turbines development tends towards larger wind farms built in deeper waters and further from the coast. Extending the current water depth limit of 50 m for the fixed substructure concepts will significantly expand the potential of the deeper seas for offshore wind farms [3][4][5][6]. The development of big floating wind farms of multi-MW machines entails new challenges for engineers.…”

A Novel Tripod Concept for Onshore Wind Turbine Towers

“…Required structural design verifications are described in pertinent recommendations [24][25][26][27] and guidelines [28][29][30]. Issues that have attracted particular attention include the arrangement of stiffening rings to improve buckling resistance [31][32][33], measures to recover the lost strength and stiffness due to the man-door opening near the tower base [34][35][36][37][38] and the design of ring flange connections between consecutive segments [39,40]. Extensive research efforts have been directed towards structural analysis and design methods [41][42][43][44][45][46][47], as well as towards optimizing the design to achieve reduced tower weight and cost [10,[48][49][50][51].…”