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

对约240个混凝土柱体进行了压缩疲劳试验，研究了疲劳概率分布的形式；ii)试件尺寸、混凝土性能（包括静强度）的影响。载荷频率对疲劳强度和疲劳寿命的影响较大。试验结果表明，疲劳寿命分布为对数正态分布或3- prater Weibull分布，混凝土强度、试件尺寸、加载频率（0.1 ~ 15 Hz）等因素对疲劳强度影响不大，但静强度的散点对疲劳寿命的散点影响较大。其次，研究了淡水中钢筋混凝土梁的疲劳特性。从这些试验中可以清楚地看出，在水中试验的钢筋混凝土梁的破坏模式是剪切破坏，而在空气中是弯曲破坏。提出了一种可用于高精度估算钢耳在水中疲劳寿命的初步公式。碳纤维增强塑料（CERP）板粘接允许在构件的截面钢筋的不足量，以弥补外部。因此，由于CFRP板是生锈的屋顶，因此认为该方法应在腐蚀环境下广泛应用。本文研究了CFRP板加固RC梁在静载和疲劳荷载作用下的强度和变形特性。试验结果表明，CFRP板粘结梁在静增量荷载作用下的破坏模式为受弯破坏，其抗弯刚度和极限强度均增加。重复荷载作用下CFRP板带骨梁的疲劳破坏不是由CFRP板疲劳断裂引起的，而是由钢筋疲劳断裂引起的。用CFRP板加固的RC梁在10^6次荷载重复下的疲劳强度约为同一梁静强度的57%。少

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