Quantitative Evaluation on Decline Process of Performances of Concrete Structures

本文主要考察了混凝土劣化和/或钢筋锈蚀对混凝土结构承载能力、抗震能力、疲劳性能、美学等性能的影响，并对这些性能的下降过程进行了量化。1.钢筋氯离子腐蚀计算机模拟方法的建立：考虑混凝土中微观和宏观孔隙对氯离子和氧气扩散过程的影响，建立了混凝土中钢筋氯离子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、混凝土含水率和混凝土中存在的裂缝对钢筋锈蚀过程的影响。钢筋锈蚀对混凝土结构疲劳性能的影响：…混凝土结构疲劳性能衰退预测方程提出了钢筋锈蚀应采取的措施。在该方程中，点蚀是引起微裂纹扩展到钢筋横截面的主要因素。通过钢筋锈蚀劣化钢筋混凝土梁的疲劳试验，验证了该方程的准确性。劣质施工产生的缺陷对混凝土结构力学性能的影响：当劣质施工导致混凝土中存在蜂窝、大空洞、不规则材料等缺陷时，会影响混凝土结构的力学性能。为了弄清缺陷对钢筋混凝土梁的承载能力、韧性和疲劳性能的影响，进行了一些试验研究。结果表明，即使梁的静承载能力没有出现下降的迹象，但由于混凝土中存在缺陷，梁的疲劳性能也明显下降。温泉水中混凝土劣化预测：在分析日本几个温泉区暴露试验数据的基础上，给出了预测温泉水中混凝土劣化的定量方程。通过本研究新进行的暴露测试结果，验证了方程的充分性。较少

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