约束应力与持荷作用下锈蚀钢筋—混凝土锈胀和粘结动力特性研究

发布时间：2018-04-26 06:44

本文选题：钢筋锈蚀 + 环向约束　；参考：《深圳大学》2017年硕士论文

【摘要】：钢筋与混凝土间的可靠粘结是两者共同工作的前提基础,钢筋锈蚀是钢筋-混凝土界面粘结性能退化的主要原因。钢筋锈蚀不仅引起自身截面的损失和力学性能的退化,且锈蚀产物的体积膨胀(往往为原来的2-4倍)将引起混凝土保护层开裂,因而破坏钢筋-混凝土的界面粘结性能,严重地危害钢筋混凝土结构的安全。钢筋混凝土结构在锈蚀的同时往往承受着使用荷载且结构中存在约束,而约束应力和持荷作用的存在对钢筋混凝土的锈胀和粘结必然有一定的影响,总的来说结构在诸多因素组合的复杂环境中经受着严峻的考验。为了尽可能的模拟实际工程中结构所处环境,本文将研究环向约束、持荷作用、钢筋锈蚀率以及相对保护层等参数对钢筋混凝土锈胀和动力粘结的影响,主要内容包括以下工作:基于锈蚀产物体积协调和Fe元素守恒,考虑混凝土开裂的弹性回缩,建立了环向约束下试件表面裂缝宽度随锈蚀率时变模型;通过XCT微观试验研究锈蚀率、环向约束、相对保护层等因素,如何影响模型参数锈蚀产物填充膨胀率n。通过钢筋混凝土锈胀试验系统的研究了各参数对锈胀的影响,并用试验数据验证了理论模型的合理性。对不同锈蚀率、环向约束、相对保护层、持载应力等参数耦合下的粘结试件进行了单向加载,结果表明:环向约束下试件的粘结性能,随钢筋锈蚀率的增加先增大后减小;环向约束刚度、持载应力等级、相对保护层等都对试件的粘结性能有提升。对锈蚀钢筋混凝土粘结试件进行了变幅循环加载,并通过加载过程中粘结强度、粘结刚度以及耗能能力等指标评估了试件的粘结性能。研究发现:锈蚀率对于变幅循环粘结性能的影响也是先增大后减小;环向约束对于试件的变幅循环粘结性能有很大程度上的提升,尤其是施加了持载的锈蚀试件提升更加明显;相对保护层对试件的变幅循环粘结性能也有一定程度的提升;持载应力的存在使得试件的变幅循环粘结性能得到了提升,但随着持载应力比例的增大提升幅度逐渐降低。
[Abstract]:The reliable bond between steel bar and concrete is the premise of their joint work, and the corrosion of steel bar is the main reason for the degradation of bond performance between reinforcement and concrete interface. The corrosion of steel bars not only causes the loss of the section and the degradation of mechanical properties, but also the volume expansion of the corrosion products (usually 2-4 times of the original) will lead to the cracking of the concrete cover, thus destroying the interfacial bond property of the steel bar and concrete. Seriously endangering the safety of reinforced concrete structures. The reinforced concrete structure is often subjected to the use of the load and there are constraints in the structure while the corrosion of the reinforced concrete structure. However, the existence of the constraint stress and the holding load must have a certain impact on the corrosion expansion and bond of the reinforced concrete. In general, the structure is subjected to severe test in the complex environment of many factors combination. In order to simulate the environment of the structure in practical engineering as far as possible, this paper will study the influence of the parameters such as circumferential constraint, load retention, corrosion rate of steel bar and relative protective layer on the corrosion expansion and dynamic bond of reinforced concrete. The main contents are as follows: based on the volume coordination of corrosion products and the conservation of Fe element, considering the elastic shrinkage of concrete cracking, a time-varying model of surface crack width with corrosion rate under circumferential constraint is established. The effects of corrosion rate, circumferential constraint and relative protective layer on the filling expansion rate of corrosion products were studied by XCT microcosmic test. The influence of various parameters on the corrosion expansion of reinforced concrete was studied by means of the test system, and the rationality of the theoretical model was verified by the test data. Unidirectional loading of bonded specimens with different corrosion rates, circumferential constraints, relative protective layer, and load holding stress is carried out. The results show that the bond properties of the specimens under circumferential constraints first increase and then decrease with the increase of corrosion rate of steel bars. The bond properties of the specimens are improved by toroidal restraint stiffness, stress grade and relative protective layer. The cyclic loading of corroded reinforced concrete bonded specimens was carried out, and the bond properties of the specimens were evaluated by the bond strength, bond stiffness and energy dissipation capacity during the loading process. It is found that the effect of corrosion rate on cyclic bond properties of the specimens increases first and then decreases, and that the circumferential constraints improve the cyclic bond properties of the specimens to a great extent, especially for the specimens with holding load. The cyclic bond properties of the specimens were improved to a certain extent by the relative protective layer, and the cyclic bond properties of the specimens were improved by the existence of the holding stress, but gradually decreased with the increase of the ratio of the holding stress.
【学位授予单位】：深圳大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU375

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