Behavior of Steel Moment Frames Using Top-and-Seat Angle Connections under Various Column-Removal Scenarios

Abstract

Top-and-seat angle connections are a conventional type of steel moment connection. However, their capacity in accommodating columns loss is rarely studied. In this study, five multistory steel moment subframes using top-and-seat angle connections were fabricated and tested to investigate their performance while subjected to various column-removal scenarios, including: (1) a middle column loss, (2) a penultimate column loss, and (3) a corner column loss. Moreover, the effects of the thickness of steel angle on load resistance were quantified. The test results indicated that load-resisting capacity increased significantly with the increase of angle thickness. In both middle column and penultimate column removal scenarios, catenary action was developed in the frames. It was also noticed that flexural action dominated the load-resisting mechanism of the frames under a corner column loss scenario. For beams in different stories, similar flexural resistance was developed. However, the beams in the first story were able to develop larger catenary action than that in the second story. It is worth noting that, for a corner column missing scenario, Vierendeel action helps to enhance the flexural action significantly.