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The EERI student chapter of the University at Buffalo (UB-EERI), the MCEER Student Leadership Council, the Networking and Education Programs of MCEER, and the University at Buffalo’s Department of Civil, Structural and Environmental Engineering jointly sponsor a series of seminars on a variety of topics related to earthquake hazard mitigation. The purpose of the seminar series is to widen accessibility to timely, technical presentations by students, researchers, visitors and affiliates of MCEER. Previous seminars have been broadcast over the Internet in real-time, and can be viewed anytime at http://civil.eng.buffalo.edu/webcast. However, due to new NEES construction at Ketter Hall, this seminar could not be webcast.
Reginald DesRoches, School of Civil and Environmental Engineering, Georgia Institute of Technology, presented a seminar entitled “Seismic Retrofit Using Shape Memory Alloys,” as part of the ongoing seminar series on earthquake engineering. The seminar at UB was held on October, 28, 2002, and unlike previous seminars, could not be webcast due to construction on the NEES facility.
Dr. DesRoches began by explaining the unique characteristics of Shape Memory Alloy (SMA) including, Young’s modulus-temperature relationships, shape memory effects and high damping characteristics. Dr. DesRoches explained that the shape memory alloys (SMAs) used in the research for seismic retrofit have been used for various medical applications for several years. These applications include medical stents and dental brace wire. In the past, use of SMA for seismic application was prohibitively expensive, however, in recent years, the cost of the material has decreased significantly, making it a viable alternative for seismic retrofit of buildings and bridges.
Dr. DesRoches presented two applications of SMAs for seismic retrofit. The first uses the shape memory effect of the material implemented in partial-restrained beam-column connections in building applications. Because of the shape memory characteristic of this material, large residual deformations in the connection due to earthquake induced loading can be recovered by heating the material. Two full-scale connections were tested using the SAC loading protocol. The connection exhibited high levels of energy dissipation without significant strength degradation during the testing, and subsequently recovered large post-experiment residual deformations by heating the SMA bars in the partially restrained connection.
The second application proposed by Dr. DesRoches utilizes the super-elastic characteristics of the material to improve the seismic resistance of bridges. The SMA material was used in restrainer bars connecting a bridge superstructure to its piers. This device limits relative displacement and prevents unseating of the bridge superstructure during an earthquake event. Dr. DesRoches investigated the effectiveness of the SMA restrainer using nonlinear response-history analysis. The concept proved to be viable, and Dr. DesRoches is planning a full-scale experimental study of the SMA restrainer bars in bridge application in the near future.
--Submitted by Gordon Warn, UB-EERI secretary
In the next Bulletin, the following seminars from the UB-EERI Seminar Series, which are currently available at http://civil.eng.buffalo.edu/webcast, will be reviewed:
F. Michael Bartlett, University of Western Ontario, “Testing Full-Scale Houses Subjected to Simulated Extreme Wind Loads;”
Diego Lopez Garcia, University at Buffalo, “Tri-Center Field Mission 2002: Taiwan;”
Thomas D. O’Rourke, Cornell University, “Lessons Learned from the World Trade Center Disaster for Critical Infrastructure;”
Douglas Taylor, Taylor Devices, “The Millennium Bridge Project, London, England.”