Study on Fatigue Characteristics in Marine Concrete Structure and Improvement in it's Performance

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Compressive fatigue tests were carried out on abut 240 concrete cylinders and the following charact5eristics were investgated : i) the form of the fatiguelfe probability distribution ; and ii) the effects of specimen size, concrete properties (including static strength). and frequency of loading on the fatigue strength and the scatter in fatigue life. Test reslts indicate that fatiguelife distributions are logarithmic normal distributions or 3-praeter Weibull distributions, and that factors such a concrete strength, specimen size, and loading frequency (from 0.1 to 15 Hz) hardly affet the fatigue strength, thugh the scatter in static strength significangly affects the scatter in fatigue life.Next, the fatigue characteristics of reinforced concrete beam in fresh water was investigated. It became clear from these test that the failure pattern of a reinforced concrete beam tested in water occurred as a shear failure but as flexural failure in air. The tentative equation to estimate the sh … More ear fatigue life in water with a high accuracy was proposed.The carbon fber-reinforced pastic (CERP) plate bonding permits the insufficient amount of steel bars in the section of the structural members TO be compensated externally. Therefore, it is considered that this method should be widely used under corrosive environment snce the CFRP pate is rust-roof.In this study, the strength and deformation characteristics of the RC beams strengthened with CFRP plate under static and fatigue loading were deat with. The exeriment reveaed the mode of failure for the beam bonded with CFRP plate and subjected to static incremental oading to be flexureal failure, and both the flexural rigidity and ultimate strength to increase. The fatigue failure for the beam boned with CFRP plate under the reetitive loading was not produced by the fatigue fracture of CFRP plate but by those of steel bars. The fatigue strength at 10^6 cycles of load repetitions for the RC beam strengthened with CFRP plate was about 57 percent static strength in the same beam. Less