Title: The Influence of Rate of loading and Material Variability on the Fatigue Characteristics of Concrete

Author(s): P. R. Sparks

Publication: Symposium Paper

Volume: 75

Issue:

Appears on pages(s): 331-342

Keywords: aggre (materials); fat loading rate; lo gates; axial loads; dynamic tests; fatigue igue tests; lightwei ads (forces); plain ght aggregate concretes; concrete; strains.

DOI: 10.14359/6414

Date: 9/1/1982

Abstract:
Results are presented from a study carried out at the Building Research Establishment, United Kingdom, on the effect of rate of‘compressive loading on the fatigue characteristics of plain concrete. Specimens made with a typical normal weight aggregrate, gravel, and a manufactured lightweight aggregate, Lytag, were tested at one of two constant rates of stressing and unstressing, 0.5 MN/m2s and 50 MN/m2s. Using as a basis the static strength of the concrete at a standard stressing rate (0.25 MN/m2s), two distinct S-N curves were obtained for each type of.concrete. When related to the static strength at the same stressing rate as in the corresponding fatigue test, the results fell onto a single curve for each type of concrete. In studying the development of axial strains in the concrete during a fatigue test, it was found that the rate of strain increase per cycle of load was constant for most of the life of the specimen. It is shown that a strong correlation exists between this strain rate and the fatigue life of the specimen, and that this can be used to determine relationships between the strain rate and the true level of loading. Using these re1ationships'S-N curves are produced with very little scatter of results.