Optimization and performance assessment of tuned mass damper inerter systems for control of buildings subjected to pulse-like ground motions

Abstract

Optimal tuned mass damper inerter (TMDI) systems in controlling displacement demands on structures affected by pulse-like near fault ground motions is presented. Simplified mathematical models of three buildings and many recorded near-fault ground motions, all containing a dominant velocity pulse, are used to make this investigation valid for a wide range of structural vibration periods and ground motion frequency content. For each of these ground motions, optimal parameters of TMDIs are estimated by minimizing structural displacement demand. Time history analysis is used for structural response simulation and Genetic Algorithm is used for minimizing the structural displacement demands. The performance or lack of it of the TMDIs are investigated and explained in relation to important properties of ground motions such as the frequency and oscillatory nature of the dominant pulse contained in the ground motion. The results indicate that properly optimized TMDIs can effectively control structural response under certain circumstances. When the structure resonates with the ground motion pulse, the less impulsive the ground motion, the more effective is the control scheme. An interesting finding is that TMDIs can be very effective in controlling response of structures which are not resonating with the pulse but nevertheless experience high demands due to other frequency components of near-fault ground motions. It is found that TMDI solutions obtained by minimizing the H2 norm of the elastic transfer function are not optimal when the fundamental period of vibration of the structure is lower than the period of the dominant pulse carried by the ground motion. Such solutions also result in unnecessarily high damping in the TMDI dashpot, without any benefit in controlling structural response.