Partial factors of safety for structural materials

The introduction of partial factors of safety constitutes a useful application of knowledge arising from structural safety theory. However, this calls for precise information on the statistical parameters of the material properties concerned. With industrially manufactured materials it is, because of the accuracy with which their production process is conducted, possible to adopt very low values of γm (resistance capacity of materials). Optimally, partial factors of safety can appropriately be used in design calculations if, for the lot (or batch) of material in question, test results are available from which the factor γm for this particular lot can be determined. Various technological processes, however, make the introduction of partial factors of safety somewhat pointless, namely, if manufacture is so controlled and monitored that definite lower limits are imposed on material properties, i.e., the statistical distribution is 'truncated'.