Indian Journal of Science and Technology

Abstract

This study analyzes the buckling capacity of steel cylindrical shells that exhibit the lower segment of 2MW, 3MW and 5MW wind towers. Four cases of steel cylindrical shells are modeled: shell with neither door opening nor collar stiffener; shell with door opening but without collar stiffener; shell without door opening but with collar stiffener; and shell with both door opening and collar stiffener. Buckling capacity is analyzed numerically using finite element analysis and parametrically using Eurocode 3: Design of Steel Structures and Guideline for the Certification of Offshore Wind Turbines. In finite element analysis, buckling capacity is calculated linearly using eigenvalue analysis and non-linearly using static Riks. Results show that steel cylindrical shell with discontinuity or modification in geometry such as door opening and collar stiffener indicates local buckling. Furthermore, a 35% decline of critical (bifurcation) buckling capacity is observed when linear buckling analysis is compared to nonlinear buckling analysis. Linear buckling analysis provides a good starting point in solving buckling collapse load, but non-linear analysis delivers a more accurate assessment due to the consideration of influences in material and geometrical nonlinearity. 
Keywords: Buckling, Collar Stiffener, Door Opening, Tower Strength, Wind Tower