Modeling the Flexural Collapse of Thin-Walled Spirally Welded Tapered Tubes

The objective of this study is to develop and validate a practical finite-element modeling protocol for predicting the flexural strength and collapse behavior of thin-walled spirally welded tapered tubes that can be used as steel wind turbine towers. The overall modeling protocol consists of two parts: (1)a meshing protocol is developed considering the effects shell element type, aspect ratio, inclination angle, and density on the buckling moment relative to theoretical predictions; and (2)two patterns of geometric imperfections (eigenmode-affine and so-called weld depression) scaled to the thresholds of fabrication tolerance quality classes in Eurocode 3 are considered in nonlinear collapse shell finite-element models and the results are compared to a series of eight large-scale flexural tests of spirally welded tubes. The computational results are compared with test results in terms of moment-rotation response, stiffness, and buckling modes and show sufficient agreement to justify the further development of nonlinear analysis methods for the design of steel wind turbine towers made from thin-walled spirally welded tapered tubes.