玄武岩纤维布加固钢筋混凝土梁抗弯性能试验研究

发布时间：2019-02-26 20:09

【摘要】：近年来，，由于地震、环境侵蚀、超载等因素的影响，国内外大量的桥梁存在不同程度损伤。对于存在病害的桥梁，采用纤维增强复合材料对其进行加固是一种经济合理的解决方法。与传统加固方法相比，粘贴纤维布加固构件时截面质量增加极少，又因其具有可加工性和易操作性，在结构加固中具有明显的优势。玄武岩纤维作为一种新型纤维增强复合材料，与其它纤维相比具有优异的性能，在延性、抗腐蚀和耐高温方面高于碳纤维，生产原料来源广泛，价格低廉。因此，开展玄武岩纤维布加固钢筋混凝土构件试验研究具有重要的经济和社会效益。本文以既有损伤钢筋混凝土梁为研究对象，开展了玄武岩纤维布粘贴层数、混凝土表面处理方式及梁端锚固件数量和类型对加固梁抗弯力学性能影响试验研究。本文主要工作内容如下： (1)将两根试验梁加载至破坏，得到其开裂荷载和极限荷载。然后，对其他试验梁进行预加载至开裂。 (2)在加载预裂试验梁底粘贴不同层数（1～5层）玄武岩纤维布进行加固，然后对加固梁进行静力加载，分析了玄武岩纤维布层数对加固效果的影响。 (3)首先对混凝土表面进行凿毛处理，然后在试验梁底粘贴相同层数玄武岩纤维布加固，分析了梁底处理方式对加固效果的影响。 (4)改变梁端锚固件数量和类型，对玄武岩纤维布加固梁进行试验，分析了梁端锚固方式对加固效果的影响。本文主要结论如下： (1)试验梁极限承载力随玄武岩纤维布粘贴层数的增加而不断增大，但不呈线性关系，粘贴2～4层玄武岩纤维布时承载力提高最为显著，超过4层后纤维布发生剥离破坏。 (2)梁底凿毛处理可以有效避免粘贴界面处发生剥离破坏，提高了玄武岩纤维布的粘结加固效果。 (3)梁端锚固件是影响试验梁承载力的关键因素之一，锚固件越可靠，加固梁受力状态越良好，极限承载力越高，跨中挠度也相应减小；锚固件数量足够的情况下，继续增加锚固件数量或改变梁端锚固件的类型对加固效果的影响较小。 (4)玄武岩纤维布对试验梁裂缝的开展具有一定的抑制和延缓作用，同时可提高试验梁的整体抗弯刚度，使跨中挠度有所降低。 (5)采用玄武岩纤维布加固的混凝土梁跨中截面应变近似符合平截面假定。
[Abstract]:In recent years, due to earthquake, environmental erosion, overloading and other factors, a large number of bridges at home and abroad have different degrees of damage. It is an economical and reasonable solution to reinforce bridges with fiber reinforced composites. Compared with the traditional strengthening method, the cross-section mass of the reinforced member with fiber sheet is increased little, and it has obvious advantage in the structural strengthening because of its machinability and easy operation. Basalt fiber, as a new type of fiber reinforced composite, has excellent properties compared with other fibers. It is superior to carbon fiber in ductility, corrosion resistance and high temperature resistance, and has a wide range of raw materials and low price. Therefore, it has important economic and social benefits to carry out experimental research on strengthening reinforced concrete members with basalt fiber sheet. Based on the existing damaged reinforced concrete beams, the influence of the number of basalt fiber adhesive layers, the concrete surface treatment methods and the number and type of anchors at the end of the beam on the bending resistance of the reinforced beams has been studied in this paper. The main contents of this paper are as follows: (1) the cracking load and ultimate load of two test beams are obtained by loading them into failure. Then, other test beams are preloaded until cracking. (2) the basalt fiber sheets with different layers (1 ~ 5 layers) were pasted on the bottom of the pre-crack test beam for strengthening, and then the reinforced beams were subjected to static loading, and the influence of the number of basalt fiber sheets on the strengthening effect was analyzed. (3) at first, the surface of concrete is drilled, then the same number of basalt fiber sheets are pasted on the bottom of the test beam, and the influence of the beam bottom treatment on the reinforcement effect is analyzed. (4) changing the number and type of beam end anchors, the experiment is carried out to strengthen the beam with basalt fiber sheet, and the influence of beam end anchoring mode on the reinforcement effect is analyzed. The main conclusions of this paper are as follows: (1) the ultimate bearing capacity of the test beam increases with the increase of the number of basalt fiber sheets, but there is no linear relationship, and the ultimate bearing capacity of the test beam increases most significantly when the basalt fiber cloth is pasted with 2 ~ 4 layers of basalt fiber. After more than 4 layers, the fiber cloth was stripped and destroyed. (2) the beam bottom drilling treatment can effectively avoid the peeling failure at the pasted interface and improve the bonding and strengthening effect of basalt fiber sheets. (3) the anchors at the end of the beam are one of the key factors affecting the bearing capacity of the test beams. The more reliable the anchors are, the better the load-bearing state of the strengthened beams is, the higher the ultimate bearing capacity is, and the less the mid-span deflection is. If the number of anchors is sufficient, increasing the number of anchors or changing the type of anchors at the end of the beam has little effect on the reinforcement effect. (4) basalt fiber cloth can restrain and delay the crack development of the test beam, at the same time, it can improve the overall flexural stiffness of the test beam and reduce the deflection of the middle span. (5) the strain of mid-span section of concrete beam strengthened by basalt fiber sheet approximately accords with the assumption of plane section.
【学位授予单位】：天津城建大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U445.72

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