Citation

Hop T. Build. Sci. 1968; 3(2): 65-80.

Copyright

(Copyright © 1968, Elsevier Publishing)

DOI

10.1016/0007-3628(68)90017-0

PMID

unavailable

Abstract

Owing to the extensive mechanization of production processes as well as the development and modernization of roads, the use of concrete, both reinforced and prestressed, is constantly increasing where constructions transferring the multi-repeated, dynamic loads are concerned. The basic influence on safety and durability of such constructions is the phenomenon of material fatigue, i.e. of concrete and steel. The knowledge of fatigue strength is indispensable for designing construction by the method of limited states.Because fatigue testing is very time consuming and expensive (it involves complicated machines) information is not plentiful and does not cover all concretes in use, and a perusal of results on a world-wide scale is handicapped by the variety of test methods. Especially scant are fatigue results from tests on high strength concretes (above 500 kg/cm2) and of advanced age/ (more than 5-years old).At the Department of Communal Buildings of the Silesian Technical College the above types of test are being carried out. Results at an intermediate stage of these tests are reported in this work. So far 45 samples in the form of cube blocks and bars have been tested for fatigue. For the evaluation of fatigue strength the results of test on 33 samples were taken and linear correlation applied. Results of these tests have been compared with those published by other authors.In the course of these fatigue tests strains were measured in some samples and conclusions drawn from these measurements are given.The tests showed that the age of concrete plays a very important role in the phenomenon of fatigue. The relative fatigue strength of an old concrete is somewhat lower than that of a younger one, e.g. 28-days old, and may even fall below the 0.50 value. Repeated loading makes concrete less elastic (it causes a lowering of its modulus of deformation).

Language: en