Progressive Collapse: Failure Criteria Used in Engineering Analysis

Recent studies of progressive collapse have sought to move the design basis from one of the simple following of prescriptive requirements to approaches based on understanding, modelling and quantitative assessment. A key requirement for such approaches is the definition of a suitable failure criterion – expressed both in physical terms and in a way that accords with traditional views of structural analysis and design. The method developed at Imperial College London checks the ability of the damaged structure to attain a new equilibrium state expressed in terms of available connection rotation capacity. The effects of variations in connection type (and therefore properties) in improving resistance to progressive collapse may therefore be examined explicitly and quantitatively. Illustrative studies of this type – which employ new developments in connection modelling and frame analysis – are reported herein. The results show which strategies are most effective in providing enhanced resistance to progressive collapse.