Evaluation of Missing Column Analyses in Progressive Collapse Design Codes

Progressive collapse specifications prescribe alternate load path analysis as a means for ensuring adequate structural integrity and load redistribution capability. This approach is generally viewed as "threat-independent" in that it assumes the removal of individual columns, but does not consider the initiating event leading to the failure of these members. However, for reasons described herein, it is of interest to determine the blast loading that corresponds to column failure, which is an underlying threat implicitly assumed by these provisions. This is carried out through dynamic finite element modeling using the commercial software LS-DYNA. The modeling methods are validated using experimental results available in archival literature and sensitivity studies are performed to assess meshing requirements. As a result, the charge size and standoff distance producing failure of an individual member is determined.