EXPERIMENTAL RESULTS FOR SEISMIC RESISTANT STEEL MOMENT FRAME CONNECTIONS

Steel moment resisting frames were highly regarded for seismic resista nt design. This opinion was based on early research and observations o f their performance in past earthquakes. Its reputation was tarnished during the 1994 Northridge earthquake, because cracking was noted in m any steel frame buildings. Widely divergent opinions have been express ed regarding the causes of this cracking. The present paper examines t he results of past experiments to provide a rational evaluation of pot ential causes of the observed damage. More than 120 experiments are re viewed, and 91 are examined in detail. Comparisons across different te st programs and statistical analyses are performed. The results show t hat flexural ductility of the beam is reduced by shear yielding in the panel zone and increased beam depth. Beam-flange thickness, column or ientation, and beam span to depth ratio also influence the flexural du ctility. Other factors including welding process, the size and type of weld, and the yield stress and tensile strength of the steel are brie fly examined. The implications of these observations to engineering pr actice are summarized.