冻融循环作用下表层嵌贴CFRP-混凝土界面粘结性能的试验研究

发布时间：2018-04-20 17:06

本文选题：CFRP + 表层嵌贴　；参考：《长沙理工大学》2015年硕士论文

【摘要】：近年来,碳纤维增强塑料(CFRP)加固混凝土结构得到了飞速的发展,相比表面粘贴CFRP加固方法而言,表层嵌贴(Near Surface Mounted,简称NSM)CFRP加固技术具有材料利用率高、耐久性能好等显著优势,在工程加固领域具有很好的应用前景。然而CFRP-混凝土的界面粘结失效机理至今没有得到很好的解释,特别是冻融循环作用下的粘结失效机理更是鲜有报道,很有必要对其开展相关研究。为此,本文进行了33个CFRP-混凝土试块的单剪试验,通过考察冻融循环次数、混凝土性能、CFRP板粘结长度、槽壁厚度以及埋深等试验参数,研究了冻融循环作用下表层嵌贴CFRP-混凝土极限荷载、破坏形态、粘滑曲线、粘结失效机理等。研究结果表明:1.随着冻融循环次数的增加,C30混凝土强度逐渐降低,而C60混凝土强度却有所增加,但其增长率逐渐降低,表明冻融循环作用下C60混凝土存在二次养护效应。2.随着冻融循环次数的增加,粘结试件的破坏模式逐渐由CFRP板条拉断破坏转变为树脂胶-混凝土界面和CFRP-树脂界面剥离破坏,且极限荷载均有所降低。表明冻融循环对粘结试件造成了明显不利影响的同时,也说明其对树脂-混凝土的界面损伤率大于CFRP-树脂胶。而提高混凝土强度可以显著改善树脂胶-混凝土的抗冻融性能。3.经过冻融循环后,40mm槽边距试件薄壁混凝土发生剥落的程度明显增加,极限荷载也显著降低,表明冻融侵蚀环境下的最小槽边距应该大于40mm。此外,相比300mm粘结长度,冻融环境下粘结长度取250mm时CFRP板的强度利用率也较高,而粘结长度取450mm(4.5mm厚CFRP)时的界面粘结性能则出现明显降低。4.室温环境下CFRP板条埋置深度变化对界面粘结性能没有较大影响,经历冻融侵蚀作用后,CFRP板三面粘贴时试件不会遭受较大侵蚀,而CFRP部分外露对试件界面粘结性能有较大影响。5.分析了冻融循环对表层嵌贴CFRP-混凝土界面粘结滑移本构关系的影响,建立了考虑冻融侵蚀作用的粘结承载能力计算模型。
[Abstract]:In recent years, carbon fiber reinforced plastic (CFRP) reinforced concrete structures have been rapidly developed. Compared with the surface bonding CFRP strengthening method, the surface embedding near Surface (NSM)CFRP) reinforcement technology has the advantages of high material utilization ratio, good durability and so on. It has a good application prospect in the field of engineering reinforcement. However, the failure mechanism of CFRP- concrete interface bond has not been well explained so far, especially the mechanism of bond failure under freeze-thaw cycle is rarely reported, it is necessary to carry out relevant research. In this paper, 33 CFRP- concrete specimens were tested by single shear test. The parameters of freeze-thaw cycle, concrete performance, bond length of CFRP plate, thickness of groove wall and depth of burying were investigated. The ultimate load, failure form, adhesive slip curve and bond failure mechanism of CFRP- concrete under freeze-thaw cycle are studied. The results of the study show that 1: 1. With the increase of freeze-thaw cycles, the strength of C _ (30) concrete decreases gradually, but the strength of C _ (60) concrete increases, but its growth rate decreases gradually, which indicates that there exists secondary curing effect of C _ (60) concrete under freeze-thaw cycle. With the increase of freeze-thaw cycles, the failure mode of bonded specimens is gradually changed from tensile failure of CFRP slab to debonding failure of resin adhesive concrete interface and CFRP resin interface, and the ultimate load is reduced. The results show that the freeze-thaw cycle has an obvious adverse effect on the bonding specimens, and at the same time, it also shows that the interface damage rate of the resin concrete is greater than that of the CFRP- resin adhesive. Increasing the strength of concrete can significantly improve the freeze-thaw resistance of resin adhesive-concrete. After freeze-thaw cycle, the degree of spalling and ultimate load of 40mm thin wall concrete increased obviously, which indicated that the minimum slot edge distance under freeze-thaw erosion environment should be more than 40mm. In addition, compared with 300mm bond length, the strength utilization ratio of CFRP plate is higher when the bond length is 250mm in freeze-thaw environment, while the interfacial bond property of CFRP plate with 450mm(4.5mm thick bond length decreases obviously. 4. At room temperature, the depth change of CFRP slab has no great effect on the interfacial bond properties. The specimens will not suffer much erosion when they are bonded on three sides after freeze-thaw erosion, while the partial exposure of CFRP has a great influence on the interfacial bond properties of the specimens. The influence of freeze-thaw cycle on the bond slip constitutive relation of the surface CFRP- concrete interface is analyzed, and the calculation model of bond bearing capacity considering freeze-thaw erosion is established.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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