The use of a virtual pendulum as passive energy dissipation system for the seismic protection of buildings
Paulo B. Gonçalves1; Eliot P. Zegarra1
1 Department of Civil Engineering, Pontifical Catholic University, PUC-Rio
doi:10.20906/CPS/COB-2015-0282
Resumo
The passive control of structures using a pendulum absorber has been extensively studied in the technical literature and used in tall buildings such as the Taipei 101 in Taiwan. As the frequency of the pendulum depends only on its length and the acceleration of gravity, to tune the frequency of the pendulum with that of the structure, the pendulum length is the only design variable. However, in many cases, the required length and the space required for its installation are not compatible with the project. In these cases one can replace the classical pendulum by a virtual pendulum which consists of a mass moving over a curved surface, allowing thus for a greater flexibility in the absorber design, since the length of the pendulum becomes irrelevant and the shape of the curved surface can be optimized. Several designs are possible and the device can be used as a tuned mass damper or a base isolation system. The aim of this work is to develop a mathematical model for a building with a virtual pendulum and to study the influence of this device on the nonlinear oscillations and stability of the main system under a base excitation. Through simulations under harmonic and recorded ground motions of increasing intensity, the performance of the virtual pendulum used as a tuned mass damper or base isolation is evaluated on an SDOF structure in order to illustrate their respective advantages as well as the drawbacks inherent in their non-linear behavior. Several values of the relevant parameters are assumed in the analyses.
Palavras-chave: nonlinear vibrations; Seismic protection; virtual pendulum; base isolation