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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 19 Abstracts search results
Document:
SP75
Date:
September 1, 1982
Author(s):
Editor: S.P. Shah
Publication:
Symposium Papers
Volume:
75
Abstract:
SP-75 The eighteen papers included in this volume report on international research into the fatigue of concrete structures. Among the topics are fatigue in structures subject to cyclic loading in offshore and Arctic environments; hydraulic fracturing effects of water; marine corrosion and fatigue strength; the validity of Miner's hypothesis; and methods of predicting crack widths and fatigue loading.
DOI:
10.14359/14127
SP75-01
P. D. Arthur, John C. Earl, and Trevor Hodgkiess
Structural concrete is widely used in marine environments, but a relatively recent development has been its use in structures such as oil production platforms, ships, wave energy devices etc., where fatigue loading can be significant. It is well known that the effect of a corrosive environment on structural steelwork is to reduce its fatigue life, and this paper describes work in progress to determine whether or not the same is true for structural concrete, both reinforced and prestressed. Reinforced and prestressed concrete beams are being tested in unidirectional bending, and in reverse bending, in jackets containing sea-water, at slow cycling rates (about 0.17 Hz)which approximate to sea-wave frequencies. The sea-water is pH and temperature controlled and is continuously circulated from a storage tank. Control specimens are tested at higher frequencies (3 to 5 Hz) and these show the expected reduction in fatigue endurance, compared withtests in air. However, the wave-frequency test results show that deposits are formed in the flexure cracks after 3 to 4 days of cyclic loading, and this has the effect of increasing, rather than decreasing, the fatigue lives of the beams - certainly when the bending is unidirectional. Under reverse bending this effect is not yet confirmed, although the crack-blocking is observed to take place. Electron-microscopy of the failure surface is being utilised to establish the mechanism by which corrosion fatigue failure occurs under these conditions.
10.14359/6399
SP75-08
E. W. Bennett
An account is given of eight fatigue tests on rein-orce concrete beams incorporating two types of mechanical splice, namely a single cold-forged sleeve and a screwed coupler connecting two cold-forged sleeves. The tests enabled the limiting range of bar stress to be found approximately, and the deflection and width of cracks were satisfactory under this range provided that the screwed coupler was fitted with a lock nut. In a comparative test, a beam with conventional splices consisting of straight lapped bars withstood the same fatigue stress as the cold-forged splices, but with increased deflection and maximum crack width. A second beam in which the lapped bars were cranked failed at a lower stress by fatigue fracture at one of the bends.
10.14359/6406
SP75-14
Harvey Haynes and M. B. Balachandra
Nine fiber-reinforced-concrete spheres were subjected to external pressure loading; four spheres were tested to failure by static loading, and five by low-cycle fatigue loading. The state of stress in the wall of the spheres was multiaxial, varying from biaxial on the inside surface to triaxial elsewhere. The average triaxial state of stress was 0 1 = a2 and 0 3 = 0.3 CT . 1 The fatigue data show a substantial difference in behavior compared to that of previous work on confined concrete. Changing the stress levels, c 9 from 0.70 to 0.50 changed the cycles to failure from 10 to 346, respectively. However, a better parameter to describe fatigue behavior was the stress-to-strength ratio, (qcyc/f;' which varied from 1.55 to 1.08, respectively. Under triaxial compression, it appeared that cyclic loading in which all principal stresses cycle was a considerably more severe condition than cyclic loading in which only one principal stress cycles while the other two principal stresses remain constant.
10.14359/6412
SP75-18
Knut Waagaard
The paper presents a short summary of the state of the art with respect to fatigue strength of reinforced and prestressed concrete structures. The simplification made in ordinary design evaluations are shortly discussed. Offshore concrete structures are exposed to an environment which is different from that compared with ordinary land structures. The special feasures of this difference will be discussed. Specially, the nature of the environmental loads causes a random load application in the structure. The paper will discuss how this may be tackled in design. Different methods used in evaluation the fatigue strength of offshore concrete structures are discussed and a proposal is made, on how to formulate a design criteria for offshore concrete structures with respect to fatigue strength evaluation.
10.14359/6416
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