The Ellipse of Elasticity and Mohr Circle-based graphic dynamic modal analysis of torsionally coupled systems

A graphic dynamic method of modal analysis of elastic torsionally coupled systems is presented, which complements the graphic recursive approach referred to as Ellipse of Elasticity Modal Analysis (EEMA) (Faggella 2013) with the introduction of a single-step Mohr Circle Modal Analysis (MCMA). The approach allows a fully graphic computational visualization of all the parameters of interest for dynamic analysis, such as the modal frequencies, the effective modal stiffness and masses, the intensity and line of actions of the elastic and inertial forces. It provides insight into the behavior of torsionally coupled systems and represents a basis for the definition of a graphic dynamic response analysis of irregular structures subjected to horizontal forces such as earthquake and wind.