Aligning progressive collapse with conventional structural design

Progressive Collapse is an increasingly important feature of modern structural design, with its profile having been dramatically raised as a result of the World Trade Centre collapse. But the subject has been recognised . and some provision made in Codes and Standards . for over 40 years, largely as a result of the Ronan Point collapse in the UK. The current situation regarding Progressive Collapse is reviewed, with particular reference to the way in which the rather prescriptive approach usually employed contrasts with the much more scientific treatment of other, more familiar aspects of structural design i.e. serviceability and ultimate strength. It is suggested the this situation can only be corrected once a better treatment of the fundamental mechanics of Progressive Collapse is developed, and some ideas based on recent work at Imperial College London are used to illustrate what is needed.