Experimental and Computational Assessments of Progressive Collapse Resistance of Reinforced Concrete Planar Frames Subjected to Penultimate Column Removal Scenario

Abstract

Existing research studies have primarily examined the progressive collapse of frame structures under an inner column removal scenario. However, progressive collapse risk is much higher when penultimate columns close to the structural periphery are damaged due to weaker horizontal constraints. A static progressive collapse test was thus conducted in this study on two single-story beam-column planar substructures with flange slabs, in which a penultimate and an inner column were removed respectively. Compared to the specimen with an inner column removal, the specimen with a penultimate column removal exhibited a larger vertical displacement under the small deformation stage, which further reduced the contribution of the compressive arch action to the collapse resistance. Under the large deformation stage, the resistance of the specimen with an inner column removal increased significantly, while that with a penultimate column removal was not enhanced notably because the horizontal movement of its edge column resulted in a smaller rise of steel strains under the catenary action. The internal forces were calculated using the measured strain data at the key sections of the slab-flange beams. The calculated results also confirm that the compressive arch action and catenary action were unable to be fully developed in the specimen with a missing penultimate column. Finally, the outcome of the vulnerability assessment of the prototype reinforced concrete frame reveals that there might be a potential risk of progressive collapse to the structure under large deformations when a penultimate column on the ground floor is damaged and the risk is higher when a penultimate column on the top floor is damaged.