Progressive Collapse Analysis of Moments Resisting Frames with Cruciform Columns Semi-Buried in Concrete

Local damage caused by the removal of one or more elements in structures lead to progressive collapse and results in partly damage to the structure, increasing damage rate and total collapse of the structure. Most buildings are designed and constructed regardless of their vulnerability to such loads. The purpose of this study is to investigate the progressive collapse in the moment frame system in a 12-story building with three openings in two different states. The frame is firstly studied with single cross columns and secondly considering two first floors using semi-buried cross columns in concrete. In order to investigate the effect of the number of lower composite floors on the overall behavior of the frame and the effect of system changes on the height of the structure from the composite frame to the steel frame, the SAP2000 software has been used for nonlinear static analysis and the deformability was studied. Dynamic nonlinear analysis of the two structures is also was performed using OpenSees software under the loading recommendation by the GSA code. The results of the analysis show that the adjacent column to the removed column bears the largest axial force and the probability of failure in this column is more than the other ones in the first floor. Therefore, this column should be designed with a higher safety factor. Also, the beam located in the middle of the first floor in the composite frame has the highest DCR and its probability of failure is greater than the other beams.