Evaluation Methods of Mechanical Performance of RC members Application of Non-destructive Testing to Evaluation of Mechanical Performance of RC Beams with Corroded Reinforcing Bars by salt damage

一般来说，混凝土检查用于确定结构的当前强度和耐久性。然而，很难从检查结果中确定结构的强度和性能，因此目前使用通过目视观察裂缝、通过无损检测的腐蚀水平等进行间接估计。因此，开发一种能够以标准化的方式直接判断结构现状的方法，将有助于提高结构管理的合理性。本研究首先，对钢筋被电腐蚀的钢筋混凝土梁进行了各种无损检测（超声波法、半电池电位法、极化电阻法）。试样是宽度为230 mm、高度为230 mm、长度为1500 mm的钢筋混凝土梁，拉伸侧具有3根跨度为75 mm的钢筋。钢筋保护层距离试样的侧面和底部为33 mm。 关于我们 对钢筋进行了腐蚀强化试验。将样本放置在金属板的顶部，金属板位于充满3%盐水溶液的不锈钢容器的底部。以金属板为阴极，从试件突出的钢筋为阳极，通入1 mA的直流电，制成电路。设置两个电流周期，14天和28天，以使试样具有不同的腐蚀水平。其次，损伤地图，反映了无损检测的结果。然后将结果输入到有限元法（FEM）分析中，并对测试样本的力学性能进行研究。最后，通过对钢筋锈蚀后的钢筋混凝土梁进行抗弯承载力试验，验证了有限元分析结果的正确性.根据各种无损检测方法的结果估计的劣化图，可以掌握锈蚀钢筋混凝土梁的劣化程度。进一步证实了有限元分析是评价结构力学性能的有效方法.利用非破坏性试验的结果，可以用有限元分析的方法从整体上模拟锈蚀钢筋混凝土梁的裂缝特性和荷载-位移响应。然而，有限元分析无法模拟加载试验与特殊的破坏模式。由此可见，在分析模型中，混凝土表面腐蚀裂缝的复制是十分重要的。少

Generally, concrete inspections are applied to determine the current strength and durability of a structure. However it is difficult to determine the strength and performance of a structure from inspection results, therefore currently indirect estimation from visual observation of cracks, corrosion levels from nondestructive test among others are used. Therefore, developing a method to directly determine the current conditions of a structure in a standardized manner will enhance rationalization of management of structures.In this study, first, various non-destructive tests (Ultrasonic Methods, Half Cell Potential Methods and Polarization Resistance Methods) were performed on reinforced concrete beams whose reinforcing bars have been corroded through electricity. The specimen was a rein-forced concrete beam of width 230 mm, height 230 mm and length 1500 mm with the tensile side having 3 reinforcing bar at a 75 mm span. The rebar cover was 33 mm from the sides and bottom of the specimen. … More Corrosion enhancement experiment was conducted to rebar. The specimen was placed on top of a metallic plate sat at the bottom of a stainless steel container full with 3% saline solution. A circuit was made with the metallic plate as the cathode and the rebar protruding from the specimen as the anode and 1Amp direct current fed into the circuit. Two periods of current flow, 14 days and 28 days were set in order to have specimens with varying levels of corrosion. Second, damage maps were made which reflect the results of nondestructive tests. The results were then input into finite element method (FEM) analysis and the mechanical performance of the test specimens investigated. Last, the adequacy of the FEM analysis results were confirmed by carrying out flexural loading tests on the rein-forced concrete beams whom reinforcing bar have been corroded.The following conclusions were obtained in this study.1. It was possible to grasp the extent of deterioration in a corroded reinforced concrete beam from deterioration maps estimated by results of various nondestructive test methods. Furthermore, the use of FEM analysis as an effective method in evaluation of structures' mechanical performance was confirmed.2. It was possible to use FEM analysis utilizing results from nondestructive test, to simulate on the whole the crack properties and load-displacement response of reinforced concrete beams with corroded rebar. However, FEM analysis was unable to simulate loading tests with peculiar failure modes. From the above, it is of the view that the importance to replicate cracks on the concrete surface caused by corrosion, in the analysis model has been made clear. Less