Study on the deterioration of structural performance of RC members due to rebar corrosion

对钢筋腐蚀程度与钢筋混凝土结构性能的关系进行了定量评价，并对碳纤维板在钢筋腐蚀恶化的钢筋混凝土结构加固中的应用进行了研究。得到了以下结果：有限元分析表明，不同腐蚀形式的裂缝方向不同，局部腐蚀需要更多的锈蚀量才能产生覆盖层混凝土的裂缝。在有限元分析中，将钢筋在点蚀和均匀腐蚀下的力学性能表示为钢筋失重率的函数，并引入钢筋本构律。3 .对不同腐蚀程度的钢筋进行了拉拔试验，并将粘结强度和粘结刚度表示为钢筋失重率的函数。采用锈蚀钢筋单元和粘结单元本构法，对锈蚀钢筋混凝土梁进行了有限元分析。将分析结果与实验结果进行比较，验证了本构律的有效性。碳纤维板对腐蚀钢筋混凝土梁的抗弯抗剪强度均有较好的增强效果。由于薄板的剥落决定了梁的强度，足够的粘结面积使梁的强度和变形性能都得到提高。围箍减重30%以上，柱的围箍效果消失，柱的强度下降，主要原因是受保护层混凝土开裂引起的粘结破坏、受保护层混凝土剥落、受保护层混凝土断裂引起的围箍效果降低和钢筋强度降低。

The study was made on the quantitative evaluation of the relationship between the level of rebar corrosion and the structural performance of RC members, and on the application of carbon fiber sheet to strengthening of RC members deteriorated due to rebar corrosion. The following results were obtained.1. Finite element analysis showed that the direction of cracking differed according to the forms of corrosion and the localized corrosion needed more amount of rust to create cracking of cover concrete.2. The mechanical properties of rebar subjected to pitting corrosion and uniform corrosion were expressed as a function of the weight loss percentages of rebar and introduced into the constitutive law of rebar in FEM analysis.3. Pull-out tests were conducted on rebars corroded to different extent, and the bond strength and the bond stiffness were expressed as a function of the weight loss percentages of rebar.4. Using the constitutive law of corroded rebar element and that of bond element, finite element analyzes were made on RC beams with corroded rebars. Comparing the results of the analyzes to the experimental results, the validity of the constitutive laws were examined.5. Carbon fiber sheet was effective for the strengthening of both bending strength and shear strength of RC beams with corroded rebars. As the peeling of the sheet determines the strength of beams, sufficient bond area make both the strength and the performance of deformation of beams increase.6. Confining effect disappeared in column above 30% of weight loss of hoop and the strength of column decreased, resulting from the bond failure due to the cracking of cover concrete, the spalling of cover concreate, the decrease of the confining effect due to the breaking of hoop and the decrease of the strength of rebar.