Simplified Methods for Progressive Collapse Assessment of Frame Structures

Abstract

The Imperial College Robustness Assessment Framework is a methodology—based upon application of the alternate load path concept—for quantitatively comparing the performance of different structural arrangements to a threat-independent triggering event (removal of a single column) with the potential to induce a progressive collapse of the structure. Initially, it depended upon the numerical analysis of a representative beam. More recently, the application of more basic structural mechanics has been found to yield almost identical results at a fraction of the cost, thereby making use of the approach by nonspecialists far simpler. Although this study was mainly restricted to the coverage of steel and composite frame structures, the principles apply to any construction type. Important aspects of these simplifications, including demonstrating both the accuracy and rigor of the resulting approach and the ease with which many variants of a proposed scheme may be compared in such a way that the precise influence of key variables may readily be assessed, are collected together herein.