【作者】 尹世平；

【导师】 徐世烺；

【作者基本信息】 大连理工大学 ， 结构工程， 2010， 博士

【摘要】 纤维编织网增强混凝土(Textile Reinforced Concrete,简称TRC)是一种新的高性能水泥基复合材料,它是多轴纤维纺织物和精细混凝土的结合,具有良好的定向增强能力和限裂能力。由于所采用的纤维材料具有耐腐蚀性,防止化学侵蚀的混凝土保护层不再需要,从而TRC结构单元的厚度主要依赖于增强纤维必需的锚固厚度。这些特性使TRC可以广泛应用于薄壁轻质的结构或覆层材料,耐腐蚀构件,已有结构的修补增强及防治各种形式的混凝土开裂。但由于所用纤维本身的脆性特征,使TRC结构达到极限荷载时没有明显的破坏预兆；而普通钢筋混凝土结构则由于特殊保护层厚度的限制,具有较大的自重,且不能有效限制结构的主裂缝发展。为此,本文结合国家自然科学基金重点项目“混凝土结构裂缝的形成与发展机理及控制技术的研究(50438010)”中的关于混凝土结构裂缝控制新方法的研究,在对TRC相关材料性能和力学性能研究的基础上,提出一种采用纤维编织网和钢筋联合增强混凝土结构的新思路,并开展了一系列的试验和理论研究工作,主要内容总结如下：1.精细混凝土的弹性模量比相同抗压强度的普通混凝土低,但极限荷载处应变较大；当用试验得出的模型参数值替代同等强度普通混凝土的参数值,试验曲线和模拟曲线吻合得比较好。2.精细混凝土在断裂过程中也要经历一个裂缝稳定发展的过程才会达到失稳破坏,且其起裂韧度随试件尺寸的增大而减小而失稳断裂韧度基本保持不变；考虑荷载位移曲线的尾部曲线下的面积后,获得的断裂能几乎不存在尺寸效应,可认为是一个材料常数。3.单独拉伸纤维束获得的应力一应变曲线几乎是完全线性的。假定基体材料开裂后只有纤维编织网承担荷载,从而由TRC薄板试件单轴拉伸的荷载一变形关系获得的纤维束的应力一应变关系可合理简化为双线性的形式。4.在同样的保护层厚度下,纤维编织网表面粘砂,混凝土中掺加短切聚丙烯纤维及在纤维编织网上挂U型钩都有助于改善构件的受力性能,保护层厚度在3mm左右可满足纤维粘结锚固的要求。5.纤维束的表面处理与径向纤维对维编织网和精细混凝土间的界面粘结性能有着较为明显的影响。对于粘细砂处理纤维束,搭接长度不小于60mm可满足纤维束间应力传递的要求；在同样的搭接长度下,绑扎搭接纤维束的增强效果要优于胶接的。6.基于RC结构的抗弯设计理论,针对环氧树脂浸渍过的纤维编织网增强精细混凝土的抗弯计算理论进行了研究,结果表明：无论布设几层网,开裂之前,理论值和试验值几乎一致；开裂后,计算值和试验值的变化趋势基本一致。7.提出纤维编织网联合钢筋增强混凝土结构的设计思路,分析了这种结构适筋梁的受弯发展过程,基于平截面假定按非线性分析理论给出了整个受力过程不同阶段梁的承载力、M／φ关系和跨中挠度的解析计算公式。最后通过与试验结果的对比,验证公式的合理性。8.针对不同的纤维编织网用量给出了纤维编织网联合钢筋增强混凝土受弯梁的两种界限破坏状态,并给出了这两种状态分别对应的配网率与钢筋配筋率之间的关系。然后,基于平截面假定,给出了此构件在三种破坏形态下正截面极限承载能力的计算方法。结合试验数据说明了第一种破坏模式的不利性,且采用本文方法得到的承载力计算值与试验结果吻合得较好。9.TRC加固钢筋混凝土(RC)梁的弯曲性能的试验结果表明,纤维编织网的表面粘砂处理能更好地发挥其有效约束能力,从而充分发挥TRC增强层的限裂和增强作用；新老混凝土的界面植入U型抗剪销钉可以提高增强后RC梁的整体受力性能,而涂抹界面剂对其几乎没有影响。此外,精细混凝土中掺加聚丙烯纤维有助于提高构件的起裂荷载；在RC梁配筋率一定的情况下,提高TRC层中的配网率可以有效地延缓结构主裂缝的发展,减小裂缝的宽度和间距,明显地提高梁的屈服荷载和极限承载力。10.模拟了TRC加固RC梁的荷载与跨中位移曲线,计算值与试验结果吻合得较好；基于RC结构的裂缝间距和宽度计算理论,定性的分析了纤维编织网对RC结构的裂缝计算中控制参数的影响。更多还原

【Abstract】 Textile-reinforced concrete (TRC) is a new high performance cementitious composite material consisting of multi-axial textile reinforcement made with advanced textile technology and fine-grained concrete. It has excellent ability of directional strengthening and delaying crack. Due to the wonderful corrosion resistance of fiber materials, the concrete cover is no longer needed as a chemical protection. The thickness of TRC members depends primarily on the necessary value to ensure a proper anchorage of the reinforcement and to avoid splitting failure. These features make TRC be widely used in the thin-walled structure with light weight or the cladding material, the corrosion-resistant components, retrofitting or strengthening the existing structure and treating various forms of cracks in the concrete. However, due to the brittle feature of fiber materials, the TRC structural member has no distinct failure symptom when it arrives at its ultimate load. At the same time, ordinary reinforced concrete (RC) elements have large dead weight and can not efficiently restrict the expansion of the main crack of structures because of the restriction of their special cover thickness. Therefore, in this study, combined with the research about the new method for crack control of concrete structures in the Key Program of the National Natural Science Foundation of China (No.50438010)"Research on the Mechanism of Crack Formation and Propagation in Concrete Structures and Crack Control Method", and based on the investigation on the related materials and mechanical properties of TRC, a new architecture reinforced with a combination of textile and steel bar in this study is proposed. Further, a series of tests and analytical work about this new architecture have been carried and the main contents are summarized as follows.1. Compared with ordinary concrete with similar compressive strength, the Young’s modulus of fine grained concrete is lower, and the strain at ultimate load is higher. When the experimentally determined control parameters are used, experimental curves show very good agreement with the calculated curves.2. It also exists a nonlinear fracture process and a steady crack propagation stage before unstable fracture of fine grained concrete, and with the increase in beam depth the unstable toughness does not change, but the initial fracture toughness decreases. After the area under the tail of the load-deflection curve is taken into consideration, the fracture energy of fine grained concrete almost does not have size effect and therefore it may be considered as a material parameter. 3. When the yarn is tensioned alone, its stress-strain relationship is almost linear. Assume that only the textile bears the load after matrix material cracking, thus the stress-strain relationship of the yarn, which is obtained from the curves of the load vs. deformation with uniaxial tensile test of TRC-thin plate specimens, can be reasonably simplified as the bilinear form.4. For the component with the same cover thickness, sticking sand on the surface of the textile, adding the short-cut polypropylene fiber into fine grained concrete and hanging U-shaped hooks upon the textile are helpful to improve its mechanical performance. The cover thickness of 3 mm or so is enough to meet the anchorage requirement of the reinforcement fiber.5. The warp yarns and the surface treatment of the textile have significant influences on the interfacial bond performance between the textile and the fine grained concrete. For the textile covered with fine sand, its splicing length, which is no less than 60mm, can meet the requirement of the stress transfer between yarns. At the same splicing length, the enhancement capacity of the textile using the binding splicing is better than that of the textile using the sticking splicing.6. Based on the bending design theory of RC elements, the flexural calculation theory of fine grained concrete reinforced with epoxy resin-impregnated textile is studied. The results show that before cracking, it can be obtained a well fit between the theoretical curves and the experimental curves regardless of the layers of textiles laid, and after cracking, comparison between the calculated and the experimental results reveals satisfactory agreement.7. A new architecture reinforced with textile-combined steel is proposed in this study. The flexural development process of the proper beam with this new structure is investigated and based on the plane section assumption, analytical equations are derived by using nonlinear analysis theory, including the load-carrying capacity at different stages and moment-curvature relationship and mid-span deflection during the entire loading process. Comparison between the calculated and the experimental results reveals satisfactory agreement and thus verifies the feasibility of the equations.8. Two kinds of limit failure state of flexural beam strengthened with textile-combined steel are presented for different amount of the textile, and for each state, the relation between the textile ratio and the steel reinforcement ratio is derived in this study. Afterward, based on the plane section assumption, the calculation methods for the ultimate bearing capacity of the normal section of this component at three kinds of failure mode are also presented. The experimental results show that the first failure mode is unfavorable to the component and the calculated values of ultimate bearing capacity coincide well with the experimental values. 9. The experimental results of flexural performance of reinforced concrete (RC) beams strengthened with TRC show that sticking sand on the epoxy resin-impregnated textile can make its anti-crack ability better exert and thus the crack-control and reinforcing function of TRC layer can be fully utilized, and embedding U-shaped pins into the old concrete contributes to improve the whole mechanical behavior of RC beams strengthened with TRC, but smearing interfacial agent on the surface of the old concrete has almost no effect on the beams. In addition, mixing polypropylene fiber into fine grained concrete is helpful to enhance the initial cracking load of the component.And when the ratio of steel reinforcement is constant, increasing the ratio of textile reinforcement in TRC can effectively delay the development of main cracks of the structure, and decrease the crack width and the crack spacing and significantly improve the yield load and ultimate bearing capacity of the beams.10. Comparison between the calculated and the experimental load vs. deflection curves of RC beams strengthened with TRC reveals satisfactory agreement. Based on the calculation theory for the crack spacing and width of RC elements, the influences of the textile on the control parameters for the crack calculation of RC structures are qualitatively analyzed.更多还原