contents | back | next
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 current construction at Ketter Hall, this seminar could not be webcast.
On Friday, September 20, 2002, Dr. Andre Filiatrault of University of California at San Diego gave a lecture entitled “Development of Post-Tensioned Energy Dissipating Connections for Steel Moment Resisting Frames.” It was the tenth presentation in the ongoing seminar series on earthquake engineering topics held at the University at Buffalo.
Mr. Darren Vian, Ph.D. candidate at the Department of Civil, Structural and Environmental Engineering (CSEE), president of the UB-EERI Student Chapter, and member of the MCEER Student Leadership Council (SLC), opened the seminar by welcoming the audience. The lecturer was introduced as well by Dr. Michel Bruneau, Professor and MCEER Deputy Director, who talked about the outstanding research trajectory of the speaker.
Dr. Filiatrault began his presentation by introducing the features of the post-tensioned energy dissipating connections (PTED), and how the self-centering characteristics can be achieved by means of post-tensioned bars without the need of full penetration welds between the flanges of the beams and the columns.
The PTED system is a combination of two important elements:
The work presented by Dr. Filiatrault is the result of an analytical and experimental study conducted at University of California at San Diego. The analytical model of PTED connections was performed idealizing the post-tensioned bars as nonlinear elastic elements, and the energy-dissipating bars as elements with hysteretic behavior. The analytical results were verified by experimental evaluations of a half-scale steel moment resisting frame. Exterior and interior connections were tested and the results were in good agreement with the analytical model.
According to Dr. Filiatrault, with a properly proportioned post-tensioned force, no shear connection is required between beam and column. The shear is transferred through Coulomb-type friction at the beam-to-column interface. Therefore, a special treatment of the steel surfaces would increase the friction coefficient and the shear capacity of the connection. Furthermore, the dowel action of the ED and the PT bars provide a redundant mechanism in the case of a loss of the post-tensioned force.
The analytical model as well as the cyclic test showed that the PTED connection has the capability to undergo large deformations, and producing significant energy dissipation, without compromising the integrity of the surrounding structure (i.e., beams and columns remain undamaged, without residual drift).
Dr. Filiatrault is expanding his work on this concept of an energy dissipating system. Future investigation will be focused on other interesting aspects, such as the reliability verification of the friction shear transfer mechanism, and the system response incorporating the effect of a concrete slab supported by the beams.
Dr. Filiatrault’s presentation was received by generous applause, after which Mr.Vian moderated the discussions. After Dr. Filiatrault answered some questions from the audience, the seminar was closed.
- Submitted by Ramiro Vargas,UB-EERI vice-president, University at Buffalo
Note: A review of Reginald Des Roches seminar, “Seismic Retrofit Using Shape Memory Alloys,” held October 28, 2002, will be included in the next issue of the Bulletin.