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 soil-structure 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 time-domain 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.
Enhancing Seismic resilience in urban environments through the vibrating barrier device
Coronado Jimenez, J. (Author). Mar 2019
Student thesis: Doctoral Thesis