Presenters: S. Nagarajaiah, Rice University, Houston; A. M. Reinhorn and M. C. Contantinou, University at Buffalo, Buffalo; M. Symans, RPI, Troy; D. Taylor, Taylor Devices, Buffalo; J. Zhang, UCLA, Los Angeles
There is no cost to attend this webinar. PDHs will be available from EERI after the webinar for $30.
Traditionally researchers have focused on supplemental damping systems for earthquake protection. The NEES-Adapt-Struct team has focused on the development of supplemental adaptive stiffness systems for stiffness shaping in structures and apparent weakening for seismic protection. This webinar presents various stages of development of the concept of adaptive passive stiffness shaping achieved through the introduction of supplemental negative and positive tangential stiffness, and the design procedure for implementing it in various structures. The team at Rice University, University at Buffalo, RPI and UCLA funded through the NSF NEES program have developed practical and true negative stiffness system. The aim of the current project was to develop a true negative stiffness system and mimic "yielding" while retaining the main structure either in the elastic range or in the mildly inelastic range with reduced inelastic excursions-leading to a new concept called "apparent weakening." The webinar presents the invention of the Negative Stiffness Device (NSD) and process that lead to the invention of the NSD—a creative process of innovation by a team of researchers. The innovation of apparent weakening concept is presented. Detailed analytical and shake table test results are presented to show the effectiveness of the new and innovative concept of adaptive negative-positive tangential stiffness which allows stiffness shaping in structures and apparent weakening for earthquake protection. Effectiveness of NSD in base isolated structures, inelastic single and multistory buildings, and based isolated bridges is demonstrated using experimental and analytical results obtained in the NEES-Adapt-Struct project.
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