Behavior of Steel Double-Channel Built-Up Chords of Special Truss Moment Frames under Reversed Cyclic Bending

Abstract

Results from the tests of six cantilever double-channel built-up members under reversed cyclic bending are presented. The main parameters investigated were stitch spacing and lateral bracing requirements in order to sustain large inelastic rotations, such as those induced by severe earthquake events. Experimental results indicate that current lateral bracing requirements specified in the AISC-LRFD provisions are not adequate to prevent lateral–torsional buckling of individual elements, as well as of the entire built-up member. Based on the results from this research, a new equation is proposed for stitch spacing for interconnection of individual channels. In addition, lateral bracing for the overall member is required near the plastic hinge region to ensure total plastic hinge rotation capacities on the order of