ABSTRACT
Passive energy dissipating devices have shown great potential for seismic hazard mitigation for civil engineering structures. They require little or no power and can significantly enhance structural performance by reducing inelastic deformation demands on the primary lateral load resisting system and the drift, acceleration and velocity demands on nonstructural components [Soong and Dargush 1997]. Passive devices can usually be categorized as rate-independent devices (e.g., hysteretic or friction systems) and rate-dependent devices (e.g., viscous or viscoelastic systems), where the force output of the latter type of devices is dependent on the rate of change of deformation. The NEHRP recommended provisions [BSSC 2003] allow the structural engineer to utilize passive damping devices to attain performance similar to that of conventional lateral load resisting systems. The design methods of structures with passive energy dissipation systems are usually based on an approximate or iterative approach. Experiments are often required to evaluate and validate these design methods. Moreover, when the seismic devices are rate-dependent, real-time experiments are necessary to acquire accurate and reliable results.
