Seismic performance of steel frames with reduced beam section connections

Reduced beam section (RBS) moment resisting connections are among the most economical and practical rigid steel connections developed in the aftermath of the 1994 Northridge, California, earthquake. Although extensive experimental testing and some numerical simulations have shed light on the behavior of this type of connection, system level studies of RBS steel frames are still quite limited. As part of this research, nonlinear pushover and transient analyses of 4-, 8-, and 16-story frames with RBS connections are conducted with the objective of developing a better understanding of RBS frame behavior and exercising as well as critiquing the recently published FEMA-350 design specifications. The analyses confirm that in spite of inherently low overstrength, RBS frames are capable of economically providing good seismic performance in regions of high seismic risk. Other structural behavior issues with design implications are also discussed.