The speed of the collapse of the World Trade Center towers, and another building in the complex, WTC7 (which had not been damaged in the original attack), has caused considerable heart-searching amongst the engineering profession. Why did the towers collapse at all? Why did they collapse so quickly? Was there anything that could sensibly have been done to prevent it? Above all, should we change our design methods for high- or low-rise buildings as a result? The general discussion is not helped because many of the statements being made by those involved appear to take account of potential future litigation, or possible changes in the future marketplace.
The talk will look at the original construction, the influence of economic considerations, the importance of fire protection and the general principle of "robustness". Engineering problems will be addressed but the lecture is aimed at a general audience and will show that we are all, in some respects, responsible for forcing less than ideal engineering solutions. It is an updated version of a talk given to the 2nd year students in their Engineering in Society Course soon after the event.
