Ships and Offshore Structures, Vol.12, No. S1, pp.S153-S173, 2017

Ultimate strength of cylindrical shells with cutouts

Author(s): S.E. Lee, S. Sahin, P. Rigo, M. Park & J.K. Paik

Abstract:
Cutouts – perforations that are often made in wind turbine towers to allow access or passage – can also reduce the towers’ ultimate strength. Thus, cutouts may need to be included in the ultimate strength formulations for wind turbine towers as an influential parameter, where significant. The aims of this study are to examine the effects of cutouts on the ultimate-strength characteristics of wind turbine towers and to propose empirical formulae to predict the reduced ultimate strength under axial compression and pure bending. The structural features of cutouts and towers in real wind turbines are investigated, and the effects of different design variables – such as shape, location, aspect ratio, column slenderness ratio, and column aspect ratio – on the ultimate-strength behaviour are described. The ultimate strengths of the towers are computed using elastic–plastic large-deflection finite element analyses. Empirical formulae accommodating a whole range of actual dimensional characteristics of cutouts and towers are derived and proposed. The findings of this research and the proposed formulae have the potential to enhance the structural design and safety assessment of wind turbine towers.