Shear plastic oscillations of a wind turbine tower

The vulnerability of wind turbine towers is an actual theme, considered the recent diffusion of aeolian parks. In many cases collapses of wind towers after severe actions have been observed. The analysis of structures subjected to variable actions can be performed by means of several methods with different levels of accuracy. Nonlinear dynamics is generally considered the most reliable one. This paper presents a numerical procedure for the analysis of rigid-plastic response of a wind turbine tower, considered a cantilever beam subjected to harmonic forcing motion of the base support. The failure is assumed depending on the formation shear hinges and the results are expressed in general terms for application to real cases. The proposed model is an evolution of the cantilever model with a single degree of freedom, since the plastic hinges can form in every section of the beam. For the solution of the problem, a numerical procedure has been developed that provides simple relationships between the strength of the structure and parameters useful for design purposes. The approach presents the advantages of rigid-plastic procedure and an efficient representation of the post-elastic behaviour of the structure, low computational competence and limited number of mechanical parameters are involved.