The collapse of a factoy roof in the UK under snow loading is described. The mode of failure was repeated in a number of similar structures. As discussed in a recent BRE Digest, these failures may have been due to the increased sensitivity of certain types of structure to snow driffing. In this paper, it is shown that the failure occurred from the unintended consequences of progress in our understanding of the structural behaviour of cold formed steel purlins. Several lessons are drawn regarding the design of these elements, the role of Code recommendations, the production of ssfe load tables for design, and the need for engineers to be aware that human action can result in unintended consequences and that decisions should be taken so as to minimise their
effects.
N.F. Pidgeon, D.I. Blockley and B.A. Turner