Discussion of Examples Using the Revised DOD Progressive Collapse Design Requirements

In the three years since Unified Facilities Criteria (UFC) 4-023-03 Design of Buildings to Resist Progressive Collapse was first published in January of 2005, various omissions, ambiguities, and opportunities for improvement were identified by civilian and government designers and engineers. A significant revision of the Progressive Collapse UFC was initiated in the fall of 2006 and was recently completed, during which a number of significant improvements were made. Readers are encouraged to refer to the newly completed document and its commentary for a discussion of revisions to the tie force procedure as well as alternate path dynamic and load increase factors, structural response criteria and other important topics. The revised Progressive Collapse UFC incorporates three example problems to demonstrate the application of the UFC requirements. This paper discusses example problems using steel, concrete, and wood structures, which illustrate the implementation of Occupancy Categories (OC) and both direct and indirect methods of providing resistance to progressive collapse.