Quantitative Evaluation on Decline Process of Performances of Concrete Structures

本研究主要考察了混凝土劣化和/或钢筋腐蚀对混凝土结构承载力、抗震能力、疲劳性能、美观性等性能的影响，并量化了这些性能的下降过程。本研究的主要结果如下：1。氯化物诱导钢筋腐蚀计算机模拟方法的发展：考虑混凝土中微观和宏观孔隙对氯化物和氧扩散过程的影响，开发了一种混凝土中氯化物诱导钢筋腐蚀的计算机模拟方法。该方法可用于定量评价混凝土质量、含水率和混凝土中存在的裂缝对钢筋腐蚀过程的影响。钢筋腐蚀对混凝土结构疲劳性能的影响：提出了钢筋腐蚀对混凝土结构疲劳性能下降的预测公式。在该方程中，将点蚀作为引起钢筋截面微裂纹扩展的主要因素。通过钢筋腐蚀引起的钢筋混凝土梁疲劳试验，验证了公式的准确性。劣质施工形成的缺陷对混凝土结构力学性能的影响：当由于劣质施工导致混凝土中存在蜂窝、大空隙、不规则材料等缺陷时，会影响混凝土结构的力学性能。为阐明缺陷对钢筋混凝土梁承载力、韧性和疲劳性能的影响，进行了试验研究。结果表明，尽管梁的静承载力没有出现下降迹象，但由于混凝土中存在缺陷，梁的疲劳性能明显下降。混凝土在温泉水中劣化预测：在分析日本几个温泉地区暴露试验数据的基础上，给出了预测混凝土在温泉水中劣化的定量方程。本研究新进行的暴露试验结果检验了方程的充分性。少

In this study, the influence of concrete deterioration and/or reinforcement corrosion on performances of concrete structure, such as bearing capacity, seismic capacity, fatigue property esthetics et al., was mainly examined, and the decline processes of these performances were quantified. The main results of this study are as follows ;1. Development of computer simulation method for chloride induced reinforcement corrosion :A computer simulation method for the chloride induced reinforcement corrosion in concrete has been developed in consideration of the effects of micro and macro pores in concrete, on the diffusion processes of chloride and oxygen. This method is useful for evaluating the influence of concrete quality, water content and crack existing in concrete on the corrosion process of reinforcing steel quantitatively.2. Influence of the reinforcement corrosion on the fatigue property of concrete structure :An equation predicting the decline of fatigue property of concrete struct … More ure due to reinforcement corrosion was proposed. In this equation, the pitting corrosion was introduced as a main factor causing the micro crack propagation into cross section of steel bar. Accuracy of the equation was confirmed by the fatigue test of reinforced concrete beams deteriorated due to the reinforcement corrosion.3. Influence of defects built up by the inferior construction on the mechanical properties of concrete structures :When some defects, such as honeycomb, large void and the irregular materials, exist in concrete due to the inferior construction, the mechanical properties of concrete structure would be affected by them. Some experimental study was done for clarifying the influences of the defects on the bearing capacity, toughness and fatigue property of reinforced concrete beams. From the results, it was confirmed that the fatigue property of the beams clearly declined on account of existing the defects in concrete even if no declination sign was appeared on the static bearing capacity.4. Deterioration prediction of concrete under hot spring water :Quantitative equations to predict the deterioration of concrete in the hot spring water were provided on the basis of analyzing the data obtained from the exposure tests under the several hot spring areas in Japan. Adequacy of the equations was checked by the results of the exposure test carried out newly in this study. Less