RETHINKING THE EARTHQUAKE ENGINEERING PARADIGM: FROM RESPONSE REDUCTION TO RESPONSE SUPPRESSION

摘要

In this paper, the authors present an earthquake engineering alternative to the long revered concept of "effective damping" by looking to a phenomenon, herein termed Stiffness Fluctuation (SF). SF is unrelated to energy dissipation, and provides response suppression, either preceding or during the attainment of maximum cycles of response, by preventing the build-up of resonance induced energy in the structure. SF response suppression (SFRS) is categorically distinct from response reduction and can occur in the absence of energy dissipation. The phenomenon is introduced via analytical studies which intentionally preclude the occurrence of hysteretic energy dissipation. The analyses demonstrate that for a variety of earthquakes, substantial SF response suppression occurs for nonlinear elastic systems as compared to otherwise equivalent linear and bilinear elastic systems, even when those systems have the same damping and essentially the same secant stiffnesses throughout their earthquake response. The authors present studies which demonstrate that SFRS is a significant factor in structural behavior, as is energy dissipation, and by itself results in levels of "effective damping" typically associated with hysteretic structural systems. The authors propose that SFRS should promulgate a diminution of the emphasis currently placed on energy dissipation in the prevailing earthquake resistant design paradigm. As an alternative to such emphasis, it is proposed that the industry look toward development of structural systems with enhanced SF characteristics such that response suppression will occur even at relatively low amplitude response displacements.