PERFORMANCE-BASED SEISMIC DESIGN AND BEHAVIOR OF ACOMPOSITE BUCKLING RESTRAINED BRACED FRAME

摘要

The concept of Buckling Restrained Braced Frames is relatively new and recently their use has increasedrnin the U.S., Japan and Taiwan. However, detailed design provisions for common practice are currentlyrnunder development. Since the summer of 2002, researchers at the University of Michigan (UM) havernbeen working cooperatively in a joint study with research team at the National Center for Research onrnEarthquake Engineering (NCREE), Taiwan, involving design, analysis and full scale testing of such arnframe by pseudo-dynamic method.rnThe selected structure is a three story, three bay frame consisting of concrete-filled-tube (CFT) columns,rnsteel beams, and composite buckling restrained braces. The frame was designed using an Energy-BasedrnPlastic Design procedure recently developed by co-author Goel at UM. The method utilized selectedrntarget drifts (2.0% for 10% in 50 year and 2.5% for 2% in 50 year design spectra for this frame) andrnglobal yield mechanism. Because of the need for more precise control of design clearances between thernend connections and steel casing of the braces, buckling restrained braced frames are excellent candidatesrnfor application of this newly developed design methodology.rnThe paper briefly presents the energy-based approach developed at UM as well as a modal displacementbasedrndesign procedure adopted by the research team at NCREE for calculation of design base shear forrnthe frame. Results from inelastic response analyses of frames deigned by the two methods for a Taiwanrnearthquake are compared. The same frame was also designed for a U.S. location and analyzed underrnground motions scaled for U.S. standards. The frames designed by the UM approach exhibitedrnsatisfactory dynamic responses for both Taiwan and U.S. ground motions.