Experimental Study on Progressive Collapse Performance of Frame with Specially Shaped Columns Subjected to Middle Column Removal

摘要

A static collapse experiment was carried out to study the progressive collapse resistance and failure mechanisms and modes of a 1/3-scale, 2 x 3-bay, and 2-story reinforced concrete frame with specially shaped columns subjected to middle column removal. A vertical concentrated load was applied to the top of the middle column to simulate the gravity load of the upper floors and the applied load was statically transmitted to the adjacent columns through the frame beams and slabs during the collapse process. The frame collapsed when the vertical displacement of the joint on the top of the failed column reached 170 mm due to the failure of beam-column joints. Based on the experimental phenomena and results, the progressive collapse-resistant behavior of the model frame is analyzed and the redistribution and transition of the load resisting mechanisms are discussed. It is concluded that the redistribution of internal force was mainly realized via the beam resisting mechanism and the compressive arch action in beams played an important role to improve the collapse-resistant capacity.