FRP管与混凝土的粘结性能试验研究

发布时间：2019-02-17 10:54

【摘要】：传统材料桩(钢桩、混凝土桩、木桩)在滨海腐蚀环境中耐久性问题突出,服役过程中需要昂贵的加固和修复费用,具有较高的全寿命成本。FRPC桩(Fiber Reinforced Polymer Pile Filled with Concrete)是FRP外壳和其内部充填混凝土形成的一种新颖组合桩基础形式。由于FRP材料与传统桩材料的性能有显著差异,主要体现在各向异性、表面硬度及粗糙度等方面,为确保FRP管和混凝土共同工作,有必要开展FRP管与混凝土的粘结性能研究。为此,本论文依托国家自然科学基金项目“水平循环荷载作用下FRPC组合桩基本特性研究”(51478109),针对FRP管与混凝土界面粘结性能这一关键问题,采取理论分析和室内模型试验研究手段,分析了粘结形式、长细比、径厚比、混凝土强度和混凝土类型等因素对其粘结滑移性能的影响规律,主要内容和成果如下：1.进行了FRPC组合桩粘结机理分析,从理论上推导了FRP管混凝土界面粘结应力与FRP管表面纵向应变的关系,得到了FRP管与混凝土的粘结滑移本构模型的理论表达式。2.设计并进行了33根FRP管混凝土试件的推出试验(pushout test),基于试验结果,分析了FRP管与混凝土试件粘结力的组成、粘结破坏的特点及其发展规律,对比了不同粘结形式FRP管混凝土试件的荷载—滑移曲线(P-S曲线)和粘结应力—滑移曲线(τ-S曲线)受力特征阶段。3.通过控制变量的试验方法,重点分析了FRP管混凝土试件粘结形式、长细比、径厚比、混凝土强度和混凝土类型等因素对其粘结滑移性能的影响。试验结果表明：(1)当几何尺寸一致时,内部螺纹型试件的界面粘结强度最大,内设抗剪件型试件其次,直接粘结型试件最小；(2)长径比对FRP管混凝土试件的粘结强度无明显影响；(3)径厚比越小,FRP管混凝土试件的粘结性能越好；(4)混凝土强度对直接粘结型FRP管混凝土试件粘结性能呈正相关性影响,但对内部螺纹型和内设抗剪件型试件粘结性能无明显影响；(5)膨胀混凝土试件的界面粘结性能明显优于相同几何尺寸的普通混凝土试件。4.通过在FRP管混凝土试件外表面张贴纵向电阻应变片,揭示了纵向应变和粘结应力沿接触界面的分布规律。试验结果表明在临近界面粘结破坏时,FRP管表面纵向应变沿高度呈三角形分布,界面粘结应力沿FRP管高度方向基本均匀分布。根据推出试验结果,分别对内部螺纹型和内设抗剪件型FRP管混凝土试件的极限粘结强度进行了回归统计分析,得到了极限粘结强度回归方程。5.综合理论及试验研究结果,提出了直接粘结型膨胀混凝土试件、内部螺纹型试件和内设抗剪件型试件的界面粘结滑移简化本构模型。
[Abstract]:The durability of traditional material piles (steel pile, concrete pile, wood pile) in coastal corrosion environment is very serious. FRPC pile (Fiber Reinforced Polymer Pile Filled with Concrete) is a new type of composite pile foundation formed by FRP shell and its inner filled concrete. The properties of FRP and traditional pile materials are obviously different, mainly in the aspects of anisotropy, surface hardness and roughness. In order to ensure the joint work of FRP pipe and concrete, it is necessary to study the bond property between FRP pipe and concrete. Therefore, based on the project of National Natural Science Foundation of China, "Research on the basic characteristics of FRPC composite pile under horizontal cyclic load" (51478109), this paper aims at the key problem of bond behavior between FRP pipe and concrete interface. By means of theoretical analysis and laboratory model test, the effects of bond form, aspect ratio, diameter to thickness ratio, concrete strength and concrete type on the bond-slip properties are analyzed. The main contents and results are as follows: 1. The bond mechanism of FRPC composite pile is analyzed. The relationship between the bond stress at the interface of FRP pipe and the longitudinal strain on the surface of FRP pipe is derived theoretically, and the theoretical expression of the bond-slip constitutive model between FRP pipe and concrete is obtained. 2. Based on the test results, the composition of bond force between FRP pipe and concrete specimen, the characteristics of bond failure and its development law are analyzed. The load-slip curve (P-S curve) and bond stress-slip curve (蟿 -S curve) of concrete specimens with different bond forms are compared. 3. Based on the experimental method of controlling variables, the effects of bond form, aspect ratio, ratio of diameter to thickness, strength of concrete and type of concrete on the bond-slip properties of concrete specimens of FRP pipe are analyzed. The experimental results show that: (1) when the geometry size is the same, the interfacial bond strength of the internal threaded specimen is the largest, the internal shear specimen is the second, and the directly bonded specimen is the smallest; (2) the ratio of length to diameter has no obvious effect on the bond strength of concrete specimens of FRP tube, (3) the smaller the ratio of diameter to thickness, the better the bond performance of concrete specimens of FRP tube. (4) the concrete strength has a positive correlation with the bond behavior of the concrete specimens of the direct bonded FRP pipe, but has no obvious effect on the bond properties of the internal threaded concrete specimens and the internal shear specimens. (5) the interfacial bond property of expansive concrete specimen is obviously better than that of ordinary concrete specimen with the same geometric size. 4. The distribution of longitudinal strain and bond stress along the contact interface is revealed by placing longitudinal resistance strain gauges on the external surface of FRP tube concrete specimens. The experimental results show that the longitudinal strain distribution along the surface of the FRP tube is triangular and the interfacial bond stress is uniformly distributed along the height of the FRP tube when the bond failure is near the interface. According to the experimental results, the regression statistical analysis of the ultimate bond strength of internal threaded and shear-resistant FRP pipe concrete specimens is carried out, and the regression equation of ultimate bond strength is obtained. Based on the theoretical and experimental results, a simplified constitutive model of interface bond-slip for directly bonded expansive concrete specimens, internal threaded specimens and internal shear specimens is proposed.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU398.9

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