Evaluation of progressive collapse potential of multi-story moment resisting steel frame buildings under lateral loading

The aim of this study is to investigate whether MRF steel structures that have been designed based on seismic codes, are able to resist progressive collapse with damaged columns in different locations under seismic loading. For this purpose, 3-D and 2-D push-over analysis of structures is carried out. The progressive collapse potential has been assessed in connection with 5 and 15-story buildings with 4 and 6 bays by applying the alternate load path method recommended in UFC guidelines. Member removal in this manner is intended to represent a situation where an extreme event, such as vehicle impact or past earthquake shock or construction error, may cause a critical column, as a result of local or global buckling, to lose a part or whole of its load bearing capacity. In contrast with 3-D models, two-dimensional frames represent a higher sensitivity to base shear reduction and element removal. In the case of middle column removal, the structure is more robust than in a corner column removal situation. The influence of story number, redundancy and location of critical eliminated elements has been discussed.