Experimental Evaluation of Replaceable Energy Dissipation Connection for Moment-Resisting Composite Steel Frames

Abstract

There is increasing recognition that conventional ductility-based design of structures for collapse prevention may not be sufficient in a modern society that demands higher-performing alternatives. Such a reality has motivated research on structural systems that minimize the disruption and cost of repairs following major earthquakes. This paper presents the experimental investigation of an asymmetrical moment-resisting connection that concentrates damage in replaceable angles at the bottom flange, achieving a repairable connection in the presence of a concrete slab. A total of three full-scale subassemblies of beam-to-column composite connections were tested with two different types of angle configurations: reduced section angles and end-reinforced angles. The results demonstrated that the proposed asymmetrical connection exhibited a stable and full hysteretic behavior up to .36 rad story drift. The replaceability of the bottom angles was confirmed during the tests, and the replaced specimens showed a strength of .8 times the original strength at the initial stage, increasing to .95 after .15 rad. The angles were replaced after specimens experienced drifts up to .2 rad for this asymmetrical connection with similar subsequent performance. Although evident buckling of angles was observed, the strength degradation from one cycle to the next was .93 up to approximate .4 rad story drift. There was a negligible stiffness decrease in the asymmetrical connection compared with the same continuous composite beam when the moment capacity ratio was .5 or greater.