Catenary effect of multi-story steel moment frame under asymmetric horizontal constraint

Abstract

In terms of the structural robustness, there have been enormous studies on the catenary effect of frame structure subjected to mid-column removal. However, it will be a more common scenario that the column at various locations will probably fail so that the asymmetric constraint from the surrounding frame will be imposed upon the affected bays. Regarding the limited studies involving these issues, a static pull-down testing is hereby performed to explore the catenary effect of the multi-story frame under asymmetric horizontal constraint. Based on the full-range structural response, the floor dependency of the catenary effect and the asymmetric constraint have been confirmed to have a significant influence on the failure sequence of bolted connections, and the evolutionary histories of internal forces. The floor dependency of the catenary effect will cause the greatest deformation demand and consequently the earliest failures of connections at the 1st floor, while the asymmetric constraint will lead to the earlier ruptures of the connection adjacent to the constraint bay than those connected to the corner column. In addition, these two factors will also result in the weak catenary effect of the overall frame, featuring the negligible vertical resistance contribution from the axial tension at the 2nd and 3rd floors due to the insufficient horizontal constraint. Eventually, the high-fidelity numerical analysis including the fracture simulation is performed and validated by the excellent agreement involving the full-range force-displacement relationship, failure modes and sequences, and the local deformation.