Influence of Effective Parameters on Rigidity of the Floor on Beam's Chord Rotation Capacity in the Progressive Collapse of Steel Moment Frames

The progressive collapse of a structure is the development of an initial local damage that damage extends in the structure and structural failure occurs. There are many parameters that can effect on the resistance of structure against progressive collapse. One of these parameters is rigidity of the floor that less attention in its modeling has been paid. Therefore, in this paper effect of the floor's rigidity has been discussed on the resistance of structure against progressive collapse. For this purpose, beams of span that it’s column has been removed, with metal deck floor is modeled in the finite element software. Since the rigidity of the floor is effective in the progressive collapse, three-dimensional moment frame structure with metal deck floor has been modeled in the ABAQUS software. The nonlinear static analysis (push down analysis) and the nonlinear dynamic analysis are used to investigate the progressive collapse. In the nonlinear static analysis, the column will be removed and the gravity load with the magnification coefficient equal two will be applied to the span that it’s column was removed. Then the gravity load gradually increases. The nonlinear dynamic analysis in the progressive collapse consists of two steps. In the first step, gravity load of the column that has been removed, is replaced as a concentrated force. In the second step, dynamic load is defined as the short time and the nonlinear dynamic analysis is done. The investigations of this study show that considering rigidity of the floor in the modeling, has an important influence on the results of the progressive collapse. Considering the rigidity of the floor increased the maximum vertical load. Thus, regarding with progressive collapse, rigidity of the floor should be reviewed and considered in the modeling.