Beam-over-Column Bracing Requirements in Continuous Steel Frame Buildings

摘要

Instability at beam-over-column connections in continuous steel frame building construction has resulted in numerous building failures. Despite these failures, and well-publicized stability research about this subject by others, many engineers still fail to appreciate the critical nature of these connections by omitting either beam web stiffeners, beam bottom flange lateral bracing, or both, at beam-over-column connections. One reason cited for this omission is that the beam was designed to preclude the use of either stiffeners or bracing at the beam-to-column intersection. It has been the authors' experience that justification for this omission typically results from either a failure to check, or a misapplication of, the web sidesway buckling provisions of AISC Specification Section J10.4.rnThis paper uses a finite element model to examine the web sidesway buckling provisions of AISC Specification Section J10.4 as they apply to beam-over-column connection design, and to examine the relative efficiencies of providing either beam web stiffeners or bracing at these connections. A parametric study was performed using a finite element frame model to compare the critical buckling loads of beams with beam web stiffeners, beam bottom flange bracing, or both, at beam-over-column intersections compared to unstiffened or laterally unbraced beams.