DEVELOPMENT AND EXPERIMENTAL VALIDATION OF A SELF-CENTERING SYSTEM FOR DAMAGE AVOIDANCE DESIGN

During the past decade, High-Force-to-Volume (HF2V) dampers has been introduced and used as an energy dissipater in seismic applications. Common applications include beam to column connections in steel and reinforced concrete moment resisting frames and bracing members in braced frames systems (Mander et al., 2009). Several studies have been conducted to investigate the characteristics and performance of these dampers more specifically at the University of New Zealand (Rodgers et al., 2018). The dampers enjoy high dissipation energy capacity and high resistance to low cycle fatigue. However due to high unloading stiffness they normally result in high residual deformations under cycle loads and have weak selfcentering characteristics (Muir, 2014). In recent years some self-centering strategies have been suggested to improve theirbehavior and to use them as part of devices for seismic damage avoidance design of structures. For example, they have been used in conjunction with prestressed cables in beams and columns to reduce the residual deformations after intense seismic event. Nevertheless due to low deformation capacity of cables and complexities in their positioning and erection their actual use in buildings is limited. In this research, a new hybrid system is introduced to overcome the weaknesses of HF2V damper and eventually to use it as a damage avoidance mechanism in RC slotted beam connections. The main purpose is to study the behavior and feasibility of combining the lead dampers (HF2V) with pre-pressed disc springs to achieve self-centering characteristics. For this purpose, the cyclic behavior of the parallel damper and disc springs are evaluated considering two different arrangements of the disc springs. At first, the governing equations for the system are developed to predict the behavior of the collection. Then the components of the proposed system are constructed for laboratory tests. Special measures are taken into consideration in the construction of the damper so that to easily apply various pre-pressures on the disc springs. Separate tests are carried out to evaluate the force-deformation behavior of the damper, disc springs and their combinations under quasi-static cyclic condition using a 1000 KN servo hydraulic test system