Document Type: Original Article
Department of Civil Engineering, Faculty of Engineering, University of Zanjan, Zanjan, Iran
One of the common methods of the inactively controlling structures subject to earthquakes is the use of Tuned Mass Damping (TMD) systems. These dampers consist of three major parameters, namely mass, damping and stiffness. TMDs generally reduce the response domain by influencing a mode, which is most often the first mode of the structure. Since the TMD parameters remain constant during vibrations, it is very important to tune them correctly and optimally. In this study, a ten-story structural model with mass irregularities has been investigated. The mass ratio for the mass damper is assumed to be at 2%. Considering a nonlinear structure, to tune the frequency of the mass damper to its optimum value, proposed experimental relationships have been used.
Both regular and irregular structures have been subjected to seven near-field and far-field earthquakes and amplified dynamic analysis from 0.1g to 1.0g with 0.1g steps and mass dampers has been used to evaluate the structural behavior. Based on the analyses outcomes, it can be seen that the TMD in structures with mass irregularities shows a better performance in the first 5 floors compared to the absence of dampers. In addition, by creating mass irregularities in the floor levels, the structure becomes more prone to damages in near-field earthquakes and the performance of the TMDs is better in earthquakes of far-field nature.