Evaluation of Building Height Effects on Progressive Collapse of Steel Structures

In the field of passive defence and structural sight of that, one of the most important issues is the progressive collapse of structures that is a catastrophic structural failure mechanism, triggering by an abnormal event such as explosion that makes local damage of a key member in the structure. After that, other failures which are not directly affected by initial abnormal event, occur in the structure; eventually result in the collapse of the whole structure or to an extent disproportionate to the original failure. In this paper, the intermediate steel moment frames structures with different levels of height are studied. For evaluating the potential of progressive collapse, the alternate path method in accordance with both GSA and UFC guidelines is used in two different methods; linear static analysis and nonlinear static analysis. The results of analysis show that, generally, the potential of progressive collapse decreases with increasing the height of the structure and in the low height steel structures, there is not enough redundancy to redistribute loads of the failed elements. It is observed that the effects of the lateral loads in UFC guideline increase with increasing height of the structures and the results of linear and nonlinear analysis in the UFC guideline are closer than in the GSA guideline.