Resistance of Door Openings in Towers for Wind Turbines

Abstract

Abstract. In this paper, a study of resistance of a lower part of a wind tower including a door opening is presented. Nonlinear 3-D shell element models with real geometry of lower tower segment have been used to simulate the thin walled shell structure in order to study the influence of door opening on the strength of the tower. Two possible alternatives for strengthening the door openings were considered: (i) increasing thicknesses of plate around the opening and (ii) stiffening the opening by a stiffener. Buckling analysis and nonlinear analysis were performed to obtain critical buckling modes and strength of the tower segment. Nominal material properties of different steel grades were considered to investigate possibility of using higher strength steels. A parametric study considering possible local shell imperfections according to EN1993-1-6 has been considered. Additionally, comparative studies have been performed based on the FE model without door opening.

Nonlinear Finite Element Analysis of Tubular Steel Wind Turbine Towers near Man Door and Ventilation Openings to Optimize Design against Buckling

“…The effect of stiffened cutouts on the buckling response of cylindrical steel shells with geometric characteristics, which are typical of modern wind turbine towers, has been studied by a group of the primary author experimentally and numerically [38,39], focusing on the comparison between alternative stiffener configurations. The issue has also been addressed in the last decade by other investigators [40,41].…”

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].…”

Repowering Steel Tubular Wind Turbine Towers Enhancing them by Internal Stiffening Rings

“…Van der Woude et al [10] performed parametric studies on base isolation systems to improve the structural response of wind turbine structures during strong earthquake events; it was concluded that the use of base isolation systems reduces possible excessive dynamic displacements of the structures in seismic zones. Tran et al [11] described the influence of the door opening on the strength of wind turbine towers by means of detailed finite element models. Do et al [12] studied the structural response of towers by taking into account fatigue due to wind loads, aiming to minimize the cost of structural steel, and to optimize the design parameters of the tower base and to achieve a longer fatigue life of the towers.…”