Structures are often subjected to vehicle collision, which can be accidental or intentional as in the case of a terrorist attack. This study investigated the performance of three-story steel moment frames with span length of 5 and 10 m subjected to vehicle collision at a first-story column using finite-element analysis software. The progressive collapse potential of the model structures was evaluated first based on the alternate path approach specified in the published guidelines. The vehicle impact analysis showed that all model structures remained stable when the speed of the vehicle was 40 km=h. However at the speeds of 80 and 120 km=h, progressive collapse occurred at both model structures after collision. The overall damages obtained from collision analysis were significantly larger than those computed based on the sudden column removal approach. (C) 2014 American Society of Civil Engineers.