A Vibrating Barrier with Grounded Inerter For Non-Invasive Seismic Protection of Existing Structures (original) (raw)
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Vibrating barrier: a novel device for the passive control of structures under ground motion
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2015
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 ex...
Engineering Structures, 2019
In this paper, the concept of an ideal grounded linear inerter, endowing supplemental inertia to passive linear tuned mass-dampers (TMDs) through its inertance property without increasing the TMD mass, is considered to reduce lateral displacement demands in base isolated structural systems (BISs). Optimal tuned mass-damper-inerter (TMDI) design parameters are numerically determined to maximize energy dissipation by the TMDI under stationary white noise support excitation. Performance of these optimally designed TMDI-equipped BISs is assessed for stationary white and colored noise excitations as well as for four recorded earthquake acceleration ground motions (GMs) with different non-stationary frequency content. It is found that for fixed mass ratio the inclusion of the grounded inerter reduces significantly secondary mass displacement and stroke for all considered excitations while it improves appreciably BIS displacement demands except for the particular case of a near-fault accelerogram characterized by early arrival of a high-energy low-frequency pulse as captured in its wavelet spectrogram. More importantly, it leads further to reductions to BIS acceleration demands with the exception of colored noise excitation for which an insignificant increase is noted. The positive effects of the inerter saturate with increasing inertance and BIS damping ratio demonstrating that small inertance values are more effective in vibration suppression of BISs with low inherent damping. Overall, it is recommended to combine low damping isolation layers with large inertance and low secondary mass TMDIs.
Vibration Control of Structures through Structure-Soil-Structure-Interaction
2014
Devices such as isolators, dampers and tuned mass dampers are now widely used in the construction industry for earthquake engineering to reduce vibration in new and, in a few cases, existing buildings. The application in to existing building is in general limited by the costs and in the case of historical building by local regulations. Aiming at the vibration control of existing structures in this paper it is proposed for the first time to exploit the structure-soil-structure mechanism as a vehicle to reduce the vibrations of structures due to seismic action. Specifically a novel device, herein called Vibrating Barrier (ViBa) hosted in the soil and detached from the structure is designed to protect a given structure. The ViBa is a massive structure whose structural parameters are calibrated to absorb portion of the ground motion input energy so to reduce the vibrations of the structure. Modelling the ground motion as zero-mean quasi-stationary response-spectrum-compatible Gaussian s...
Optimal seismic response using a Passive Tuned Mass Damper Inerter (TMDI)
Journal of Building Materials, 2020
Received: 29-01-2020 Accepted: 10-04-2020 Abstract. The latest earthquakes history shows that resistant conception, safe and economical structures are a daily challenge for structural engineers. Among the newest vibration control devices figures the inerter which is a device which can develop a large fictive mass (it consists of a mass amplification effect) using rotational inertia. In this research work, the effectiveness of a traditional passive tuned mass damper (TMD) is compared with a tuned mass damper inerter (TMDI) which consists generally of tuned mass damper coupled with an Inerter. Both devices are used to control a base-isolated structure vibration submitted to several seismic records. In This study, a base-isolated structure of six stories (6 DOF) was equipped with (TMD) and (TMDI) and a time history analysis were performed under different earthquake records (El Centro, Kobe, Kocaeli). The mathematical model of the building is established in MATLAB Simulink. The simulati...
Optimum Tuned Mass Dampers under seismic Soil-Structure Interaction
Soil Dynamics and Earthquake Engineering
Tuned Mass Damper (TMD) devices are widely adopted as a valid mechanical solution for the vibration mitigation of structural systems and buildings under dynamic excitation. In the specific challenging context of seismic engineering, TMDs may represent a convenient option for both aseismic structural design and seismic retrofitting. However, the expectable efficiency rate of TMDs in that context is still debated. Besides, potential Soil-Structure Interaction (SSI) effects may become crucial in the mechanical system, and should properly be taken into account for the optimum TMD design, in order to avoid possible de-tuning. This work contributes to this framework, by investigating the effectiveness of an optimum TMD in reducing the linear structural response to strong-motion earthquakes of a given set of Multi-Degree-Of-Freedom (MDOF) low-and high-rise shear-type frame structures, by embedding SSI within the dynamic and TMD optimisation model. The TMD is seismically tuned through a dedicated two-variable optimisation procedure, for each specific case (primary structure, seismic event and soil type), therefore providing the optimum device setting for each given context. Average primary structure response indices are specifically targeted to that purpose, while maximum ones are monitored. A quite considerable range of optimisation cases is considered (eighty instances), to outline rather general considerations and average trends on TMD optimisation and effectiveness within the seismic SSI framework, for both low-and high-rise buildings. Such an investigation shall provide useful guidelines for a comprehensive tuning of TMDs in mechanical systems and specifically in the presence of seismic SSI, to be consulted in view of real-case applications.
Enhancing seismic resilience in urban environments through the vibrating barrier device
2019
Earthquakes are a well-known natural hazard to urban environments. Recent disasters in Mexico, Ecuador, Italy and Japan manifest the clear need to address the seismic resilience of existing buildings in a different and more affordable way. Construction industry has successfully introduced devices such as isolators, dampers and tuned mass dampers to mitigate dynamic vibrations induced by earthquakes in new buildings, but such devices are rarely used for the protection of existing buildings, as they generally require substantial alteration of the original structure. In the case of heritage buildings, critical facilities and urban areas, especially in developing countries, those traditional localized solutions might become impractical. Therefore, what we are witnessing nowadays is the lack of substantial actions to protect existing cities in seismic prone areas with consequent number of fatalities and loss of historic and artistic heritage. In this regard a novel device called Vibrating Barrier (ViBa) has been recently proposed. Up to now the ViBa has been only developed to protect individual structures or a small cluster of buildings. This study focuses on the enhancement of the seismic resilience in urban environments by further developing the study of the ViBa device as a non-localised vibration control strategy. To this aim a novel procedure to identify simplified discrete models of clusters of buildings in the urban environment has been proposed. This research initially focuses on the soilstructure and structure-soil-structure interaction of realistic buildings through numerical and experimental tests. One of the open research questions in this framework is the definition of the proper soil interaction mechanical parameters. This study addresses the parameter identification of simplified discrete models developing a novel two stage timedomain identification procedure. The procedure is validated against numerical models and experimental tests. The time domain identification procedure has been further extended to the urban environment using finite element models of realistic cities available in literature. A simplified discrete model has been developed to represent a cluster of buildings within the urban environment able to account for site-city interaction effects. A novel procedure to determine the optimal design parameters of the ViBa device in urban environments following a stochastic approach has been proposed. The validation of the ViBa device as a non-localised vibration control strategy has been undertaken both in a full-scale numerical model and a scaled physical model of a realistic cities. The adoption of the ViBa has been shown to be beneficial by reducing the maximum average peak displacement of every single building analysed.
Journal of Engineering and Architecture
Through intensive research and development in recent years, the PTMD has been accepted as an effective vibration control device for both new and existing structures to enhance their reliability against winds, earthquakes, and human activities. PTMDs can be incorporated into an existing structure with less interference compared with other passive energy dissipation devices [1]. The PTMD is found to be a simple, effective, inexpensive, and reliable means to suppress undesirable vibrations of structures caused by harmonic or wind excitations [2]. The main objective of incorporating TMD is to reduce energy dissipation demand on the structural members. This reduction is accomplished by transferring some of the structural vibrational energy to the TMD which, in the simplest form consists of a mass, a spring and a damper, attached to the main structure [3].