Structures that Fail Benignly

SUMMARY The safety factor, load factor and fail-safe approaches to designing for strength are briefly reviewed. It is shown that the first two are essentially the same when considering the general fitness-for-purpose philosophy. Fail-safe is advantageous when dealing with modern materials, such as structural ceramics, and with fatigue, when statistical considerations become important. An extension of the fail-safe approach, entitled ‘benign failure’ is finally presented.