Cyclic Behavior of Double Angle Connections

Abstract

An investigation was conducted to study behavior of steel double angle framing connections under severe cyclic loading of earthquakes. The studies consisted of subjecting six connection assemblages to an increasing level of large cyclic rotations until failure occurred. The connection angles were bolted to the column flange and welded to the beam web. Structural ribbed bolts taken from an existing building and high strength A325 bolts were used in test specimens. The structural ribbed bolts failed in cyclic tension when connection experienced rotations larger than 0.025 radians. Behavior of connections with A325 high strength bolts tightened to 70% of their proof loads was satisfactory and ductile. However, in these specimens, cyclic fracture of angles started when connection rotation exceeded 0.025 radians. Results of hysteresis behavior, failure modes, and variations of bolt forces are presented. Also, information is provided on applying the findings to dynamic analysis and design of steel structures with double angle connections.