A simplified dynamic analysis for estimation of the effect of rotary inertia and diaphragmatic operation on the behaviour of towers with additional masses

The present paper, deals with the dynamic analysis of a thin-walled tower w ith varying cross-section and additional masses. It, especially, deals with the effect of the rotary inertia of those masses, which have been neglecte d up to now. Using Galerkin's method, we can find the spectrum of the eigen frequencies and, also, the shape functions. Finally, we can solve the equat ions of the problem of the forced vibrations, by using Carson-Laplace's tra nsformation. Applying this method on a tall mast with 2 concentrated masses , we can examine the effect of the rotary inertia and the diaphragmatic ope ration of the above masses, on the 3 first eigenfrequencies.