ON THE DYNAMICS OF PERIODIC FOUNDATION-STRUCTURES INTERACTING WITH FRAME STRUCTURES

Resumo

A lot of research has been performed in the last years concerning dynamics of periodic structures and their ability to create band gaps at certain frequencies that dramatically reduce the vibration amplitudes of associated systems. The general idea is to create a periodic structure that filters out the vibration amplitude of a given dynamical system. For the case of dynamic systems interacting with the soil the reasoning is more complex. When a classical structural system is supported by the soil, the behavior is not unilateral. The dynamic behavior of the soil presents geometric damping, which usually damps out part of the vibration amplitude of the supported dynamical system. But there is a price to pay. The vibration amplitude of the system supported by the soil is decreased but it generates outgoing waves that will cause perturbation to the surrounding environment. There is a trade-off, less vibration on the system usually means more waves propagating into the environment. This article will address the idea of incorporating a periodic foundation structure between the soil and the dynamical system. The idea is to investigate if the periodic structure decouples the soil from the dynamic system for given frequencies. The soil is modelled by the Boundary Element Method, the periodic foundation structure is described by the Finite Element Method. The ability of the periodic foundation structure to create band gaps is distinct directions corresponding to multiple degrees of freedom will also be addressed.