Resistance of Door Opening in Towers for Wind Turbines

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.Godkänd; 2013; 20130822 (anhtra)