环向约束和持载下锈蚀钢筋混凝土锈胀和粘结性能研究
发布时间：2019-05-07 11:01
【摘要】：混凝土耐久性问题是土木工程界的一个热点问题，而钢筋锈蚀无疑是影响钢筋混凝土结构耐久性的主要因素。钢筋锈蚀以后，混凝土表面会出现纵向或者横向的裂缝、混凝土保护层脱落等现象，这些都会导致混凝土结构的承载能力降低、延性变差；混凝土和钢筋是协同合作的，这一作用的直接体现就是粘结性能，钢筋锈蚀以后，钢筋混凝土之间的粘结性能会发生退化，这严重影响了结构的安全性。实际工程中混凝土结构都是在承受荷载条件下发生锈蚀的，而且结构中都设有箍筋作为环向约束，本文在总结已有研究成果的基础上，考虑持载应力和新型加固材料FRP作为环向约束这两个因素，研究其对钢筋混凝土结构的锈胀和粘结性能的影响，这对实际工程有一定的理论价值。本文的主要研究工作如下： 对33个相同规格的试件进行了电化学加速锈蚀试验，考虑不同持载应力、有无环向约束、不同锈蚀率等条件得到不同锈蚀条件对钢筋混凝土结构锈胀开裂的影响；在此基础上分析了裂缝宽度和环向应变随着不同锈蚀条件的变化规律，，并且通过对裂缝宽度的拟合得到了钢筋混凝土结构锈胀开裂的临界锈蚀率。研究结果表明：随着持载应力的增加，裂缝宽度和环向应变增大，临界锈蚀率降低；环向约束的临界锈蚀率高于无环向约束的临界锈蚀率。 通过参考已有文献关于临界锈蚀深度的模型，考虑环向约束和持载应力这两个因素的影响，建立了不同锈蚀条件下混凝土锈胀开裂模型，分别得到了无环向约束、无持载应力，有环向约束、无持载应力，无环向约束、有持载应力和有环向约束、有持载应力这四种条件下临界锈蚀率的计算公式。并将理论结果和试验结果进行了对比，验证了该计算公式的合理性。 对锈蚀后的试件进行了拉拔试验，考虑不同持载应力、有无环向约束、不同锈蚀率等条件得到了不同锈蚀条件对钢筋混凝土结构锈蚀后粘结性能的影响规律；由此分析了试件的的极限粘结强度和粘结应力滑移曲线等随着不同锈蚀条件的变化规律，并且对不同锈蚀条件下试件的极限粘结强度进行了修正。研究结果表明：环向约束影响极限粘结强度的变化；随着持载应力的增大，有无环向约束条件下试件的滑移量和残余粘结强度都呈现下降趋势。
[Abstract]:The durability of concrete is a hot issue in civil engineering, and the corrosion of steel bar is undoubtedly the main factor affecting the durability of reinforced concrete structure. After the corrosion of steel bars, there will be longitudinal or transverse cracks on the concrete surface, and the concrete protective layer will fall off, which will lead to the reduction of the bearing capacity of the concrete structure and the deterioration of its ductility. Concrete and steel bar are cooperative, which is directly reflected by the bond performance. After corrosion, the bond performance between reinforced concrete will deteriorate, which seriously affects the safety of the structure. In practical engineering, concrete structures are corroded under the condition of bearing load, and there are stirrups as circumferential constraints in the structure. In this paper, based on the summary of the existing research results, Considering the bearing stress and the new reinforcement material FRP as the circumferential constraints, the influence of the two factors on the rust expansion and bond performance of reinforced concrete structures is studied. This is of theoretical value to the practical engineering. The main research work in this paper is as follows: electrochemical accelerated corrosion tests were carried out on 33 specimens of the same size, considering the different load-holding stresses, whether or not there is a circumferential constraint. The influence of different corrosion conditions on the corrosion bulging and cracking of reinforced concrete structures is obtained under different corrosion rates and other conditions. On this basis, the variation rule of crack width and circumferential strain with different corrosion conditions is analyzed, and the critical corrosion rate of corrosion expansion cracking of reinforced concrete structure is obtained by fitting the crack width. The results show that the critical corrosion rate decreases with the increase of the holding stress, and the critical corrosion rate of the circumferential constraint is higher than that of the uncircumferential constraint, and the crack width and the circumferential strain increase and the critical corrosion rate decreases with the increase of the holding stress. By referring to the existing models of critical corrosion depth and considering the influence of circumferential constraint and holding stress, the corrosion expansion and cracking models of concrete under different corrosion conditions are established, and no circumferential constraint and no supporting stress are obtained, respectively. The formula of critical corrosion rate under four conditions: circumferential constraint, no holding stress, no circumferential constraint, bearing stress and circumferential constraint, and holding stress, is the formula for calculating the critical corrosion rate under the conditions of circumferential constraint, no holding stress, no annular constraint, and no cyclic constraint. The theoretical results are compared with the experimental results, and the rationality of the formula is verified. The tensile test of corroded specimens was carried out. The influence of different corrosion conditions on the bond properties of corroded reinforced concrete structures was obtained under the conditions of considering different load-holding stresses, circumferential constraints and different corrosion rates. The variation rules of the ultimate bond strength and bond stress-slip curve with different corrosion conditions are analyzed, and the ultimate bond strength of the specimen under different corrosion conditions is modified. The results show that circumferential constraint affects the change of ultimate bond strength, and the slip amount and residual bond strength of specimens with or without circumferential constraints decrease with the increase of load-holding stress.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU375
[Abstract]:The durability of concrete is a hot issue in civil engineering, and the corrosion of steel bar is undoubtedly the main factor affecting the durability of reinforced concrete structure. After the corrosion of steel bars, there will be longitudinal or transverse cracks on the concrete surface, and the concrete protective layer will fall off, which will lead to the reduction of the bearing capacity of the concrete structure and the deterioration of its ductility. Concrete and steel bar are cooperative, which is directly reflected by the bond performance. After corrosion, the bond performance between reinforced concrete will deteriorate, which seriously affects the safety of the structure. In practical engineering, concrete structures are corroded under the condition of bearing load, and there are stirrups as circumferential constraints in the structure. In this paper, based on the summary of the existing research results, Considering the bearing stress and the new reinforcement material FRP as the circumferential constraints, the influence of the two factors on the rust expansion and bond performance of reinforced concrete structures is studied. This is of theoretical value to the practical engineering. The main research work in this paper is as follows: electrochemical accelerated corrosion tests were carried out on 33 specimens of the same size, considering the different load-holding stresses, whether or not there is a circumferential constraint. The influence of different corrosion conditions on the corrosion bulging and cracking of reinforced concrete structures is obtained under different corrosion rates and other conditions. On this basis, the variation rule of crack width and circumferential strain with different corrosion conditions is analyzed, and the critical corrosion rate of corrosion expansion cracking of reinforced concrete structure is obtained by fitting the crack width. The results show that the critical corrosion rate decreases with the increase of the holding stress, and the critical corrosion rate of the circumferential constraint is higher than that of the uncircumferential constraint, and the crack width and the circumferential strain increase and the critical corrosion rate decreases with the increase of the holding stress. By referring to the existing models of critical corrosion depth and considering the influence of circumferential constraint and holding stress, the corrosion expansion and cracking models of concrete under different corrosion conditions are established, and no circumferential constraint and no supporting stress are obtained, respectively. The formula of critical corrosion rate under four conditions: circumferential constraint, no holding stress, no circumferential constraint, bearing stress and circumferential constraint, and holding stress, is the formula for calculating the critical corrosion rate under the conditions of circumferential constraint, no holding stress, no annular constraint, and no cyclic constraint. The theoretical results are compared with the experimental results, and the rationality of the formula is verified. The tensile test of corroded specimens was carried out. The influence of different corrosion conditions on the bond properties of corroded reinforced concrete structures was obtained under the conditions of considering different load-holding stresses, circumferential constraints and different corrosion rates. The variation rules of the ultimate bond strength and bond stress-slip curve with different corrosion conditions are analyzed, and the ultimate bond strength of the specimen under different corrosion conditions is modified. The results show that circumferential constraint affects the change of ultimate bond strength, and the slip amount and residual bond strength of specimens with or without circumferential constraints decrease with the increase of load-holding stress.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU375
【相似文献】
相关期刊论文 前10条
1 邱兆国;梁力;张凤鹏;;混凝土结构保护层开裂时钢筋的临界锈蚀率模型[J];东北大学学报(自然科学版);2014年02期
2 张超超;曾志兴;;钢筋混凝土梁板安全锈蚀率限值探究[J];低温建筑技术;2011年09期
3 吴锋;张章;龚景海;;基于锈胀裂缝的锈蚀梁钢筋锈蚀率计算[J];建筑结构学报;2013年10期
4 Feng WU;Jing-hai GONG;Zhang ZHANG;;钢筋混凝土梁基于锈胀裂缝的锈蚀率计算（英文）[J];Journal of Zhejiang University-Science A(Applied Physics & Engineering);2014年03期
5 陈月顺;卫军;罗晓辉;;钢筋混凝土锈胀开裂临界锈蚀率模型研究[J];武汉理工大学学报;2007年02期
6 蔡新华;徐世p
本文编号：2471022
本文链接：https://www.wllwen.com/guanlilunwen/chengjian/2471022.html
