Two types of web connection details have been used for radius-cut RBS test specimens: a welded and a bolted detail. In the welded detail, the beam web is welded directly to the column flange using a CJP groove weld. For the bolted detail, preten sioned high-strength bolts are used. Specimens with both types of web connections have achieved at least 0.04 rad interstory drift angles, and consequently, both types of web connection details were permitted for RBS connections in FEMA 350 (2000b).
Previous test data (Engelhardt et al., 2000) indicate that beyond an interstory drift angle of 0.04 rad, specimens with bolted web connections show a higher incidence of fracture occurring near the beam-flange groove welds, as compared to specimens with welded web connections. Thus, while satisfactory performance is possible with a bolted web connection, previous test data indicate that a welded web is beneficial in reducing the vulnerability of RBS connections to fracture at the beam-flange groove welds.
Subsequent to the SAC/FEMA testing on RBS connections, a test program (Lee et al., 2004) was conducted that directly compared nominally identical RBS connections except for the web connection detail. The RBS specimens with welded web connections achieved a 0.04 rad interstory drift angle, whereas RBS specimens with bolted web connections failed to achieve 0.04 rad.
Thus, while past successful tests have been conducted on RBS connections with bolted web connections, other data have provided contradictory evidence, suggesting bolted web connections may not be suitable for RBS connections when used for SMF applications. Until further data are available, a welded web connection is required for RBS connections prequalified for use in SMF. For IMF applications, bolted web connections are acceptable.
The beam web-to-column CJP groove weld is intended to extend the full distance between the weld access holes to minimize the potential for crack-initiation at the ends of the welds. Hence, the requirement for the plate to extend from one weld access hole to the other. All specimens were tested with the full-depth weld configuration.