A Passive Control System Based on Double U-Shaped Metal Elements: Application Cases, Design and Developments

Currently, the cumulative damage and poor response of structures subjected to seismic action have gained an increasingly central role in the field of structural engineering, prompting research and development toward Performance-Based Earthquake Engineering. This approach relies on defining multiple performance objectives corresponding to different demand intensities. For this purpose, a new seismic low-damage-based design philosophy is proposed for both structural and non-structural components. Supplementary damping, with or without seismic isolation, is a possible strategy. The presented work, dealing with supplementary damping, will discuss studies and applications of a passive-based hysteretic device, which consists of the combination of two pairs of U-shaped metallic elements that provide either a mono-directional or two-directional dissipative response when two elements are combined appropriately. Hybrid systems can also be conceived, thanks to the versatility of the U-shaped design, allowing integration with supports, shock transmitters, and bracing systems. Past structural-wide applications in bridges and buildings have provided the opportunity to conceive high-performing devices characterized by a wide range of geometry and, consequently, structural capacity in terms of yielding forces, ultimate displacement, and dissipation. The acquired experience has allowed the development of a reliable system validated through experimental tests and nonlinear numerical finite element analyses. The construction sector is highly demanding in terms of cost and time, requiring a fast and reliable methodology for system conception and implementation, triggered by a fast preliminary design. In this framework, the system will be preliminarily described, presenting experimental and numerical studies that led to a closed-form solution for the preliminary design of the device. The application will be discussed, concluding with scheduled future developments to be expected in the framework of collaborative research that joins the expertise of the Industry and Academy.