Experimental response of beam-slab substructures subject to penultimate-external column removal

This paper presents an experimental program to investigate the progressive collapse resistance of reinforced-concrete (RC) building structures subjected to a loss of a penultimate-external (PE) column that is the exterior one nearest to the building corner. Under this accidental scenario, any mobilization of catenary action in beams and slabs bridging over the column, as an alternative load path, should rely solely on the strength of a half perimeter compressive ring forming within the deflected slab area. Three one-third scaled beam-slab substructures were designed, built, and tested by a static loading scheme to examine the overall load capacity and displacement ductility that are two aspects of the progressive collapse resistance of RC building structures. The test variables are (1) additional amounts of beam stirrups, (2) additional beam longitudinal reinforcement, and (3) the aspect ratio of the slab panel. The boundary condition of the specimens is rotationally and vertically restrained, but laterally unrestrained. A 12-point loading system is used to simulate uniformly distributed loads. Based on the test results, a simple but conservative approach to quantify the progressive collapse resistance of RC building structure under a PE column loss scenario is proposed.