Analysis of the mechanical vibrations of a complex structure as a damped single degree of freedom system

The use of finite element method software allows the modal and spectral analysis of complex structures with an accessible computational cost. In contrast, with the theory of damped systems of a degree of freedom, solutions can be obtained analytically that describe with greater generality the vibrations of structures subjected to variable forces over time. However, with analytical methods, only very simple structures can be studied. This paper presents a method that allows to calculate the rigidity and effective mass of a structure from the values of the angular frequencies of the structure, with their corresponding inertial loads. Next, the structure can analyzed as a cushioned system of a degree of freedom. In this way, it is possible to calculate the displacements and accelerations that the structure will suffer when it is excited by an external force variable over time. Subsequently, using D'Alembert's principle and a finite element program, the stresses can be calculated by a static analysis.