Simple equations for strength and deformability verification of tubular steel wind turbine towers

Abstract

Simple analytical expressions for a preliminary design of tubular steel wind turbine towers under flexure and shear are proposed. Expressions derived included local buckling effects, shear to moment interaction, ovalization of cross-section and inelastic rotation of foundation. A finite-element analysis with ABAQUS program was also conducted for examination of the ovalization effects and for the whole response of steel tube in flexure.Numerical and analytical results were compared with the experimental results of recent studies available in the literature, showing good agreement. The range of variable investigated refers to medium and large size steel wind tower with cylindrical shape having: - length to diameter ratio between 10 and 50; - diameter to thickness ratio between 100 and 300; - height to diameter of plinth ratios between 4 and 6.Ultimate (ULS) and service limit (SLS) states were considered to derive the geometrical characteristic of steel tube (diameter and thickness at the base) taking into account of main aspect concerning the structural behavior of wind towers. The paper also highlights the necessity to improve both experimental and analytical research to develop specific recommendation and expressions for hand calculation of these kinds of structures necessary for a quick preliminary design of these structures.Original contribution of research was the derivation of simple analytical expressions for strength and deformability verification taking into account of cross-section ovalization, shear to moment interaction, and P-Δ effects, all phenomenon generally considered with 3D non linear finite element analyses.