Alessandro Tombari

Vibrating barrier: a novel device for the passive control of structures under ground motion.

A novel device, called vibrating barrier (ViBa), that aims to reduce the vibrations of adjacent structures subjected to ground motion waves is proposed. The ViBa is a structure buried in the soil and detached from surrounding buildings that is able to absorb a significant portion of the dynamic energy arising from the ground motion. The working principle exploits the dynamic interaction among vibrating structures due to the propagation of waves through the soil, namely the structure–soil–structure interaction. The underlying theoretical aspects of the novel control strategy are scrutinized along with its numerical modelling. Closed-form solutions are also derived to design the ViBa in the case of harmonic excitation. Numerical and experimental analyses are performed in order to investigate the efficiency of the device in mitigating the effects of ground motion waves on the structural response. A significant reduction in the maximum structural acceleration of 87% has been achieved experimentally.

Sensitivity of the Stochastic Response of Structures Protected by the Vibrating Barrier Control Device

The sensitivity of the stochastic response of a novel passive control device named Vibrating Barrier (ViBa) developed for reducing the seismic response of structures to earthquake excitation is scrutinized. The Vibrating Barrier (ViBa) is a massive structure, hosted in the soil, calibrated for protecting structures by exploiting the structure-soil-structure interaction effect. The soil is modelled as a linear elastic medium with hysteretic damping by resorting to the Boundary Element Method in the frequency domain. In order to accomplish efficient sensitivity analyses, a reduced model is determined by means of the Craig-Bampton procedure. Moreover, a lumped parameter model is used for converting the hysteretic damping soil model rigorously valid in the frequency domain to the approximately equivalent viscous damping model in order to perform conventional time-history analysis. The sensitivity is evaluated by determining a semi-analytical method based on the dynamic modification approach for the case of multi-variate stochastic input process. A non-stationary zero mean Gaussian random process is considered as stochastic input. The paper presents the sensitivity of the maximum response statistics to the design parameters of the ViBa in protecting a model of an Industrial Building. Comparisons with pertinent Monte Carlo Simulation will show the effectiveness of the proposed approach.