The design performance of a structural element undergoing repeated application of load has of necessity been related to the behavior of comparable structural elements under repeated cycles of constant amplitude. In actual structures, a knowledge of the number and magnitude of loading cycles is needed to offer guidelines on the estimate of loading cycles to be used and the evaluation of the applicability of laboratory test data to service conditions. The factors that affect strain history, loading histories and structural fatigue testing, and statistical evaluation of full-scale fatigue tests are discussed in this paper. Also, typical load spectra and their conversion to laboratory test spectra are discussed.
"Service Histories and Laboratory Testing," Journal of the Structural Division, Proceedings of the American Society of Civil Engineers, v. 94, ST12, December 1968, pp 2699-2712.