Progressive collapse resistance of reinforced-concrete frames with specially shaped columns under loss of a corner column

Abstract

To investigate the progressive collapse potential of reinforced-concrete frames with specially shaped columns subjected to the loss of a ground corner column, a static experiment on a one-third scale, 2 × 3-bay, two-storey model frame was carried out. The experiment showed that the collapse process could be divided into four stages (elastic, elasto-plastic, plastic-hinge and collapse), and the redistribution of loads was mainly observed to occur in the components adjacent to the failed column. The load-carrying capacity of the frame decreased dramatically at a rotation angle of approximately 0·06 rad at the end of the adjoining beam, indicating the start of the frame collapse. The beam resisting mechanism was identified as the major load redistribution mechanism, and the arch action in frame beams played an important role in improving the collapse-resistance capacity. A finite-element model was developed to analyse the progressive collapse-resistance performance by utilising OpenSees. The load–displacement curve obtained from the numerical analysis compared well with the experimental result. A simplified approach to evaluate the collapse-resistance capacity of the frame is proposed.