Oren LAVAN, Technion - Israel Institute of Technology

ROCKING SEISMIC RESISTING SYSTEMS: CONCEPTS, ANALYSIS, DESIGN, AND APPLICABILITY TO IRREGULAR BUILDINGS
Linear behavior presents no limit to the forces acting on the structural system. To limit the forces acting on the structural system, traditional seismic design of buildings relies on nonlinear behavior. Such nonlinear behavior is usually obtained by allowing structures to yield. This limits the forces acting on the structural system thus allowing smaller structural elements and foundations to be used. In addition, this limits the total floor accelerations in the system and controls damage to acceleration sensitive non-structural components. Due to the plastic energy dissipated in the system, inter-story drifts are comparable to those of a corresponding linear system having a stiffness similar to the initial stiffness of the yielding system. Nevertheless, plastic energy dissipated by structural elements implies structural damage. Furthermore, plasticity hinders residual deformations that make repair expensive and sometimes not economic.
Rocking systems possess a nonlinear-elastic behavior. Thus, they present a structural system that enjoys the best of both worlds. On the one hand, the forces acting on the structural system are limited by the decompression forces. Thus, smaller structural elements and foundations are required, and accelerations are limited. On the other hand, once the seismic event ends, the system returns to its original state with no residual deformations. Furthermore, if energy is dissipated in the system, this is usually done within energy dissipation devices that sustain no damage, or ones that could be easily replaced.
The talk will discuss the concept of rocking seismic resisting systems, the various structural typologies of rocking systems and their practical applications. Advanced approaches for modelling and analysis of rocking systems as well as for their design in irregular buildings will be presented. Finally, the applicability of the various rocking systems as a seismic resisting system in irregular buildings will be analyzed and discussed.