Torsional balance of asymmetric structures by means of tuned mass dampers

Abstract

This research studies the response of asymmetrical linear and nonlinear structures subjected to unidirectional and bidirectional seismic excitation, equipped with one or two Tuned Mass Dampers (TMDs). The optimized parameters of each TMD are obtained by applying the concept of general torsional balance. The results show that the TMDs reduce the edge deformation in values varying from 20% to 50%. The highest reductions are obtained at the edges where deformation is greater. As a general rule, it has been found that the TMD should be located towards the corner where the uncontrolled response (without TMD) is greater. If the excitation is a broad-band process, the TMD tends to synchronize with the frequencies associated to the two translationally dominant modes of the structure. Instead, if the excitation is a narrow-band process, the TMD tends to synchronize with the characteristic frequency of the excitation. The findings for one or two TMDs are very similar, therefore, there is no significant improvement resulting from adding a second TMD. Preliminary results indicate that, when moderate, the inelasticity of the main structure does not significantly affect the optimized TMD frequency. However, for torsionally hybrid and flexible structures, the optimized TMD position is sensitive to inelasticity of the main structure. (C) 2012 Elsevier Ltd. All rights reserved.