08-29-2012, 08:25 PM
Seismic behavior of concentrically braced steel frames
Author: Khatib, Ibrahim F.; Mahin, Stephen A.; Pister, Karl S. | Size: 18 MB | Format: PDF | Quality: Unspecified | Publisher: Earthquake Engineering Research Center | Year: 1988 | pages: 222
UCB/EERC-88/01, Earthquake Engineering Research Center, University of California, Berkeley, 1988-01, 222 pages (515/K42/1988)
Concentrically braced steel frames designed by conventional methods may exhibit several undesirable modes of behavior. In particular, chevron-braced frames have an inelastic cyclic behavior that is often characterized by a rapid redistribution of internal forces, a deterioration of strength, a tendency to form soft stories, and fracture due to excessive deformation demand. Through analytical studies and numerical simulations, parameters having a significant influence on these phenomena are identified. Recommendations are proposed for preferable ranges of brace slenderness, approaches for designing beams, and a simplified capacity design approach for proportioning columns and connections. Optimization techniques are applied to the design of chevron-braced frames to improve their seismic response. Further improvements related to changes in structural systems are presented and discussed. These include the use of double-story X-braced framing, incorporation of a secondary moment-resisting frame, and the use of braces in a V configuration. The advantages of each of these approaches in certain circumstances are discussed. Analytical parametric studies are used to assess the disadvantages of the approaches. A new structural system, which incorporates vertical linkage elements in a conventional chevron-braced frame, is presented. The basis of this system is examined, its effectiveness is demonstrated using analytical results, and, finally, further research directions are outlined.
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