Eccentrically Braced Frames: U.S. Practice

Current status of research and U.S. codes on Eccentrically Braced Frames (EBFs) is briefly discussed. Excerpts from the just completed tentative American Institute of Steel Construction (AISC) Specification pertaining to EBFs are given in detail. Comments on these provisions attempt to interpret them in the light of research and design practice. Based on these provisions a 6-story building employing EBFs in end walls is analyzed for seismic response under the action of several severe earthquakes. For these time-history analyses it is assumed that steel behaves as an elasto-plastic material with strain hardening. The behavior of the frames is found to be satisfactory. Several recommended details for EBFs are illustrated.