Development of Link-to-Column Connections for Steel Eccentrically Braced Frames

University Of Texas At Austin, Austin TX

Investigators

Abstract

0000031 Engelhardt The objective of this research project is to develop and validate safe and economical link-to-column connections for use in steel eccentrically braced frames. The 1994 Northridge and 1995 Kobe earthquake exposed fundamental deficiencies in US design, detailing and welding practices for connections in steel moment frames. Recent research conducted in both countries, however, has lead to major strides in understanding the problems associated with steel moment connections. Eccentrically braced frames (EBFs) provide an alternative to moment frame as a lateral force resisting system in steel buildings. The higher stiffness provided by an EBF could offer important advantages over a moment frame, and the use of EBFs have been constructed since the Northridge Earthquake, many using a configuration where the EBF link is attached to the column. The link-to-column connection in such systems plays a critical role in the seismic performance and safety of the frame. Many of the welding and design conditions responsible for the poor performance of moment frame connections in the Northridge Earthquake are also present in EBF link-to-column connections. At the same time, the force and inelastic deformation demands at link-to-column connections are substantially greater than at moment frame connections. However, virtually no research effort has been directed towards link-to-column connections in EBF to date. Nonetheless, EBF construction is proceeding on he West Coast for major building projects using questionable connection details that have not been verified by testing. A program of combined analytical and large-scale experimental studies will be conducted on link-to-column connections for seismic-resistant steel EBFs. A variety of promising connection details will be investigated and refined using inelastic finite element studies. Connection performance will then be evaluated using full-scale cyclic loading tests, followed by the development of design recommendations. This project will be conducted in close collaboration with investigators at Kyoto University in Japan. The planned collaboration includes coordinated experimental investigations between the US and Japanese sides, participation of a doctoral student from Kyoto University in the US side research, an dynamic testing of specimens fabricated in the US at Kyoto University using loading equipment not available in the US. This project will also include additional collaboration with the National Center for Research in Earthquake Engineering in Taiwan. This project is supported under the 3rd-year competition under NSF 98-36. "US Japan Cooperative Research in Urban Earthquake Disaster Mitigation."