Performance and robustness of a new passive damper: Component testing, characterization, and pseudo dynamic testing

n the past 20 years, there have been witnessed appreciable seismic damage and several weak-story failures of mid-rise and high-rise buildings that have been documented after major earthquakes in urban environments; as well as recent failures of the fluid dampers end seals that resulted in detrimental leaking and an estimated retrofit cost of millions (the San Francisco-Oakland Bay Bridge located at the San Francisco Bay is an indicative example). In view of these devastating consequences, this research is partly motivated by the need to develop sustainable energy dissipation devices that do not suffer from oil leakage due to failure of their end seals and from the occasional displacement limitations of yielding steel dampers; and partly from the need to develop a robust damper that consists only of traditional civil engineering materials (sand and steel) in association with the use of post -tensioned steel rods with which practitioner civil engineers are familiar. Past failures of fluid dampers are both disruptive and costly, therefore not in-line with the current design paradigm of sustainable engineering, where the design and construction of structural systems shall meet acceptable performance levels at present and in the years to come without compromising the ability of future generations to use, maintain, and benefit from them. This study presents results from an extensive experimental campaign with a pressurized sand damper (PSD) which does not suffer from the challenges of viscous heating, the failure of its end seals and the long stroke limitations, and addresses the quest for velocity-independent (hysteretic) dissipation. The experimental campaign includes physical testing, real-time hybrid simulation (RTHS) testing and the development of the analytical model that captures the behavior of the PSD. The robustness of the PSD is also assessed by subjecting it to extreme temperatures and humidity.