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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:
SP75-11
Date:
September 1, 1982
Author(s):
Alfred G. Bishara
Publication:
Symposium Papers
Volume:
75
Abstract:
This paper presents results from an experimental investigation in which thirteen rectangular reinforced concrete beams were subjected to cyclic loading within service conditions. One beam was designed to measure the variation in steel stress and bond stress along the beam length, particularly between cracks and in the anchorage zones near the beam ends. The variables in the other twelve beams included the area of concrete concentric with each tension rebar and the ratio of compression reinforcement to tension reinforcement. Resulting bond deterioration is analyzed and its effect on bond stress distribution as well as crack development is illustrated and discussed.
DOI:
10.14359/6409
SP75-09
Ralejs Tepfencompression; fatigue (materials); fatigue tests; plain concrete; stresses; tension.
The few existing tests with stress reversals between tension and compression suggest that these may have little influence on the fatigue strength of concrete. This would instead be determined by the higher of the tensile or compressive stress maxima, expressed as percentages of the appropriate static strengths, with the minimum stress equal to zero. Two series of tests were performed to gain moreinformation. The specimens used were cubes and prisms loaded with compressive loads and transverse splitting line loads. Combination of these loads and pulsation of one of them gave the desired stress reversals. The test results indicate that stress reversals cause a slight reduction in fatigue strength. This reduction may however be due to the test equipment In the Swedish Code of Practice, a reduction of design stress due to fatigue caused by stress reversals between tension and compression is required. The results obtained are on the safe side of this requirement.
10.14359/6407
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
SP75-06
J. M. Lovegrove and Salah El Din
Reinforced concrete beams of different sizes and reinforcement arrangements were repeatedly loaded at frequencies of 0.5 and 1 Hz. Curvature and deflection are presented as ratios of the initial values and a unique relation is obtained between each of these ratios and the logarithm of the number of load repetitions. Each ratio increases gradually in a curved form to about 0.5 x l06 repetitions from where it takes a straight line form with a slope varying between 0.2 and 0.225. The long term deflections of beams tested in earlier investigations are predicted with good agreement. A similar expression is given for maximum crack width and predicted long term values are in reasonable agreement with those measured by earlier investigators.
10.14359/6404
SP75-16
P. R. Sparks
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.
10.14359/6414
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