EXPERIMENTAL RESEARCH ON COLLAPSE MECHANISM OF A RC FLAT PLATE

摘要

In collapse-resistant design of structures, it is important to understand the structural failuremechanism and alternative load paths under accidental load action. In this paper, an experimental study of an existing 4-story reinforced concrete frame model is reported. A quasi-static experimental method is proposed to simulate the sudden column loss in the flat plate frame structure. The weight of the upper structure was applied step by step to the plate's center with a mechanical jack. With the increment of slab's center displacement, the radial cracks developed at the bottom surface. The load carrying capacity is enhanced around 40% higher than the value Pyl calculated with the yield-line theory due to the compressive membrane action. And then an inverted conical damage region of around 3 times of the diameter of the circular load area appeared in the center of the flat plate when the displacement reaches to 1.81 times of the depth of flat plate section. The structure of the original load-transfer mechanism changed, and the remaining upper load was approximately 0.65 Pyl, which was taken by tension membrane. Based on the experimental results and phenomenon, the failure-mechanism of structure was analyzed, the collapse-resistant of flat plate was explored and discussed by compressive membrane and tension membrane action of flat plate.