Time: 10:00-11:30 a.m.
Date: 20th, June
Place: Room 201, He shanheng building
Title: ADAPTIVE NEGATIVE STIFFNESS SYSTEMS FOR SEISMIC PROTECTION
Abstract: Traditionally researchers have focused on supplemental damping systems for earthquake protection. Nagarajaiah group has focused on the development of adaptive/variable stiffness systems and tuned mass dampers for seismic and wind hazard protection. This seminar presents various stages of development of the concept of adaptive/variable stiffness structural systems.
Recently a team of researchers at Rice University, University at Buffalo, RPI & UCLA funded through the NSF NEES program have developed practical and true negative stiffness structural systems for seismic protection. The aim of the 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 talk 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 stiffness 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.
Professor Satish Nagarajaiah, Rice University
Bio Sketch: Satish Nagarajaiah is a Professor of Civil Engineering and of Mechanical Engineering at Rice University, Houston. His research and teaching focuses on structural dynamic systems, computational structural mechanics, earthquake engineering, adaptive stiffness structural systems, structural control, sparse structural system identification, and noncontact structural strain sensing using nanomaterials. His research is funded by the NSF, NASA, DOE, AFOSR, ONR, Private Agencies and Industries. He has developed advanced computational techniques for nonlinear dynamic analysis of base isolated structures that has resulted in the software 3D-BASIS that is used widely by academics and design professionals for analysis and design of numerous base isolated structures, such as San Francisco International airport, in the United States, and in many countries around the world. He has invented and developed adaptive stiffness structural systems—particularly adaptive passive negative stiffness structural systems and smart/adaptive passive tuned mass dampers. National Science Foundation has recognized his contributions to adaptive stiffness structural systems by awarding the NSF CAREER award in 1998 and ASCE awarded the Moissieff award in 2015 for contributions on adaptive passive negative stiffness structural systems. He has lead the development of widely cited structural system identification algorithms based on sparse time-frequency and wavelets, sparse regularization, statistical learning and low rank methods.
Recently he and his coworkers were awarded the 2017 Raymond C. Reese Research Prize for sparse structural identification of stay cables. He is the earliest researcher who invented and developed noncontact structural strain sensing using nanomaterials. He co-inventedand developed laser based noncontact structural strain sensing that produces detailed two-dimensional strain map.
Prof. Nagarajaiah has published extensively. He has presented plenary and keynote lectures at numerous international conferences. More details of his teaching, research, service, publications, and news can be found at his website satishnagarajaiah.rice.edu.
Dr. Nagarajaiah currently serves as the editor of the structural control and health monitoring international journal [Wiley], and as one of the editors of Mechanical Systems and Signal Processing, Elsevier, and editor-in-chief (North America) of the structural monitoring and maintenance international journal [Techno-press]. He served as the managing editor of ASCEJournal of Structural Engineering from 2011-2018. He is a fellow of ASCE and a fellow of Structural Engineering Institute (SEI) of ASCE. Currently, he serves on the board of governors of ASCE SEI and on the Technical Activities Division Executive Committee. He has founded and chaired numerous committees in SEI,EMI, and IASCM on Structural Control and Monitoring.
撰稿 | 陸新徵
編輯 | 張超娜
審核 | 楊軍