Seismic Progressive Collapse Evaluation in 3 Story Reinforced Concrete Buildings due to Inner Column Removal

Progressive collapse in the structures is defined failure of the entire or major part of a structure that has initiated from the small part of the building, continued in the other structural elements and in this way, progressive collapse become larger and larger in the structural elements, one after another. Finally, the remaining structural system will not be able to resist the lateral and gravity loads. So, the prediction of safety margin in buildings against the progressive collapse due to the earthquake loads is one of the important issues in the earthquake and structural engineering. In this paper, modeling of the progress and distribution of the collapse in the elements of the structures, one after another, was carried out in moment resisting reinforced concrete short buildings due to the earthquake loads and effects of the column removal have been investigated on the progress and propagation of the collapse. For this purpose, the progressive collapse potential of a 3 story reinforced concrete building with ordinary moment resisting frame has been evaluated due to the column removal in presence of FEMA_P695 two component ground motions. According to the results of the nonlinear time history analyses, collapse distribution is not affected by the earthquake records in the progressive collapse and follows a special pattern. In the early stages of distribution, collapse occurred in the beams surrounding and upper parts of the column removal area, then transferred at the height of the structure from the first ceiling to the upper ceiling, vertically and eventually, distributed horizontally in the stories. Therefore, recommendations and suggestions have been presented for seismic optimization of the reinforced concrete short buildings against the progressive collapse. Also, distribution patterns of the collapse have been presented to predict the collapse propagation due to the column removal in presence of the earthquake loads.