锈蚀钢筋混凝土粘结性能退化及其对梁抗弯刚度影响的研究
发布时间：2019-06-25 15:39
【摘要】：混凝土与钢筋之间良好的粘结性能是保证二者协同工作的重要基础，随着实际工程中耐久性问题越来越多地出现，钢筋混凝土粘结性能的耐久性也自然的成为研究者们关注的焦点。已有的研究成果表明，钢筋锈蚀已经成为混凝土结构耐久性最主要的影响因素之一，其对钢筋混凝土粘结性能的影响也不可忽略，，但是由于锈蚀产物界面上的传力机理复杂且影响因素众多，兼之理论分析体系匮乏，因此十分有必要继续展开对该领域的理论和试验研究。 本文以已有的锈蚀钢筋混凝土粘结性能退化试验为基础，通过对试块锈蚀率和极限荷载数据进行分析，得出结论：当锈蚀率低于某值（约1%）时，极限荷载逐渐变大；当锈蚀超过该值之后，极限荷载开始变小。说明在锈蚀率较低时，锈蚀产物的产生能在一定程度上提高钢筋与混凝土之间的粘结性能。 同时，研究结果表明，粘结强度与极限滑移量的衰减受锈蚀量、混凝土保护层厚度以及混凝土抗拉强度等因素影响，相较于相对锈蚀率，钢筋的绝对锈蚀量更能直观反映锈蚀对锈胀力、锈蚀裂缝和粘结强度退化的影响机制，从而选取相互独立的参数锈蚀产物厚度、混凝土相对保护层厚度与抗拉强度等，建立了多参数的锈蚀钢筋混凝土粘结强度计算式，与国内外及本文实验结果的对比验证了所选参数及所建模型的合理性。 通过在钢筋内部开槽并粘贴应变片的方法，采集拉拔试验过程中钢筋的应变，通过对钢筋应变数据和钢筋加载端及自由端滑移值数据的分析，得到多参数的锈蚀钢筋与混凝土之间的粘结-滑移关系。分析各因素对粘结刚度的影响，得出结论：粘结刚度随着锈蚀产物层厚度t的增加而不断减小；在产生相同滑移值的情况下，相对保护层厚度c/d越大，其粘结应力水平越高，粘结刚度越大。 最后，通过分析锈蚀钢筋混凝土粘结性能退化对梁抗弯刚度的影响机理，同时考虑钢筋混凝土粘结性能退化及锈胀裂缝引起的梁横截面初始缺陷对锈蚀梁抗弯刚度的影响，利用刚度解析法，推导出综合考虑钢筋应变不协调系数m、修正后的裂缝钢筋应变不均匀系数'和有效高度折减系数γ的锈蚀梁抗弯刚度的计算模型。
[Abstract]:The good bond performance between concrete and steel bar is an important basis to ensure the cooperative work of the two. With the emergence of more and more durability problems in practical engineering, the durability of reinforced concrete bond performance has naturally become the focus of attention of researchers. The existing research results show that steel corrosion has become one of the most important factors affecting the durability of concrete structures, and its influence on the bond properties of reinforced concrete can not be ignored. However, due to the complexity of force transfer mechanism on the interface of corrosion products and the lack of theoretical analysis system, it is necessary to continue to carry out theoretical and experimental research in this field. In this paper, based on the existing bond degradation test of corroded reinforced concrete, through the analysis of the corrosion rate and ultimate load data of the test block, it is concluded that when the corrosion rate is lower than a certain value (about 1%), the ultimate load increases gradually, and when the corrosion exceeds this value, the ultimate load begins to decrease. It is shown that the formation of corrosion products can improve the bond between steel bar and concrete to a certain extent when the corrosion rate is low. At the same time, the results show that the attenuation of bond strength and ultimate slip is affected by corrosion, the thickness of concrete protective layer and the tensile strength of concrete. Compared with the relative corrosion rate, the absolute corrosion of steel bar can directly reflect the influence mechanism of corrosion on corrosion expansion force, corrosion crack and bond strength degradation, so as to select the independent parameter corrosion product thickness. Based on the relative protective layer thickness and tensile strength of concrete, a multi-parameter formula for calculating the bond strength of corroded reinforced concrete is established, and the rationality of the selected parameters and the model is verified by comparing with the experimental results at home and abroad and in this paper. Through the method of slotting and pasting strain gauge in the steel bar, the strain of the steel bar in the process of drawing test is collected. Through the analysis of the strain data of the steel bar and the slip value data of the loading end and the free end of the steel bar, the bond-slip relationship between the corroded steel bar and the concrete with multiple parameters is obtained. The influence of each factor on bond stiffness is analyzed, and it is concluded that the bond stiffness decreases with the increase of corrosion product layer thickness t, and the higher the relative protective layer thickness is, the higher the bond stress level is, and the greater the bond stiffness is when the relative protective layer thickness c 鈮
本文编号：2505800
[Abstract]:The good bond performance between concrete and steel bar is an important basis to ensure the cooperative work of the two. With the emergence of more and more durability problems in practical engineering, the durability of reinforced concrete bond performance has naturally become the focus of attention of researchers. The existing research results show that steel corrosion has become one of the most important factors affecting the durability of concrete structures, and its influence on the bond properties of reinforced concrete can not be ignored. However, due to the complexity of force transfer mechanism on the interface of corrosion products and the lack of theoretical analysis system, it is necessary to continue to carry out theoretical and experimental research in this field. In this paper, based on the existing bond degradation test of corroded reinforced concrete, through the analysis of the corrosion rate and ultimate load data of the test block, it is concluded that when the corrosion rate is lower than a certain value (about 1%), the ultimate load increases gradually, and when the corrosion exceeds this value, the ultimate load begins to decrease. It is shown that the formation of corrosion products can improve the bond between steel bar and concrete to a certain extent when the corrosion rate is low. At the same time, the results show that the attenuation of bond strength and ultimate slip is affected by corrosion, the thickness of concrete protective layer and the tensile strength of concrete. Compared with the relative corrosion rate, the absolute corrosion of steel bar can directly reflect the influence mechanism of corrosion on corrosion expansion force, corrosion crack and bond strength degradation, so as to select the independent parameter corrosion product thickness. Based on the relative protective layer thickness and tensile strength of concrete, a multi-parameter formula for calculating the bond strength of corroded reinforced concrete is established, and the rationality of the selected parameters and the model is verified by comparing with the experimental results at home and abroad and in this paper. Through the method of slotting and pasting strain gauge in the steel bar, the strain of the steel bar in the process of drawing test is collected. Through the analysis of the strain data of the steel bar and the slip value data of the loading end and the free end of the steel bar, the bond-slip relationship between the corroded steel bar and the concrete with multiple parameters is obtained. The influence of each factor on bond stiffness is analyzed, and it is concluded that the bond stiffness decreases with the increase of corrosion product layer thickness t, and the higher the relative protective layer thickness is, the higher the bond stress level is, and the greater the bond stiffness is when the relative protective layer thickness c 鈮
本文编号：2505800
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