Performance Basis of Guidelines for Evaluation, Upgrade

were discovered to have brittle fractures of their beam-column connections. This behavior had not been widely anticipated, was contrary to the intended ductile behavior, and called to question the ability of such structures to reliably resist future earthquakes. On behalf of the Federal Emergency Management Agency, the SAC Joint Venture embarked on a program of analytical and laboratory investigations to determine the causes of this behavior, better understand earthquake response of frame structures, and develop design and construction recommendations that would provide structures capable of more reliable earthquake resistance. Extensive laboratory investigations provided statistical information on the hysteretic behavior of beam-column connections. Analytical investigations provided statistical information on the response of frames incorporating such connections and the ability of analytical techniques to predict this response. These investigations permitted development of a reliability-based approach for evaluation of the probable performance of moment-resisting steel frame structures. This approach forms the basis for recommended design, evaluation, repair and upgrade criteria. These design and evaluation criteria employ a Demand and Resistance Factor Design (DRFD) format that accounts for the randomness and uncertainty inherent in earthquake demand an