Code‐Oriented Methodology for the Seismic Design of Regular Steel Moment‐Resisting Braced Frames

Abstract

In order to help improve the seismic design of regular steel buildings structured with ductile moment‐resisting concentrically braced frames (MRCBFs) using the general design methodology of Mexico's Federal District Code (MFDC‐04), suitable design parameters were first assessed using the results of pushover analyses of 13 regular MRCBFs. In order to insure collapse mechanisms consistent with the assumptions implicit in a code‐based design (strong‐column/weak‐beam/weaker‐brace), it is proposed to relate the minimum strength ratio for the resisting columns of the moment frames and the bracing system. Improved equations are proposed for a more realistic assessment of ductility and overstrength factors. In a second stage, the effectiveness of the improved methodology was assessed with the design of six regular steel buildings with MRCBFs. Buildings were evaluated by performing both pushover and nonlinear time‐history analyses under ten selected artificial ground motions related to the corresponding design spectrum.