FRP-Strengthening of Slender Reinforced Concrete Columns

FRP-细长钢筋混凝土柱的加固

• 批准号: RGPIN-2016-03963
• 负责人: Sadeghian, Pedram
• 金额: $ 1.68万
• 依托单位: Dalhousie University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=708890
• 关键词: FRP; Strengthening; Slender; Reinforced; Concrete

In the past two decades, fiber-reinforced polymer (FRP) composites have emerged in civil engineering as strengthening materials with superior characteristics for the rehabilitation of existing reinforced concrete (RC) structures. It is well-known that bonding unidirectional FRPs perpendicular to the axis of an RC column (i.e. wrapping) can increase the axial load capacity of the column in compression. It is also accepted that bonding the FRPs parallel to the axis of an RC column can only increase its bending capacity, without significant strengthening effect under axial loads. This is true for a short column with low slenderness effects. However for a long (slender) column the story is completely different, where buckling induced failures can govern due to lack of lateral (flexural) stiffness. In fact, the strength of a slender RC column is a function of its slenderness and induced moment due to its lateral deformation and axial load. As a result, the flexural stiffness of a slender column controls its axial strength. The innovative aspect of this proposal, and the key difference from other strengthening approaches, is that it seeks the desired strengthening gain of a slender RC column primarily by enhancing the flexural stiffness of the column by bonding high-modulus longitudinal FRPs. In this research program, large-scale slender RC columns will be prepared and strengthened using high-modulus FRPs mainly in longitudinal direction of the column and will be tested in laboratory under axial loads with low eccentricities. The effect of circular and square cross-sections, slenderness ratio, initial load eccentricity, FRP ratio, FRP modulus, and combination of longitudinal and transverse FRPs will be studied. In addition, an in-depth study will be performed on the mechanics of FRP crushing and debonding failures that may affect the performance of the longitudinal FRPs. A comprehensive analytical modeling will also be developed and verified against the experimental data to study the effect of a broad range of cross sections, boundary conditions, material properties, and fiber orientations. The research program, upon its completion, is expected to quantify the behavior of slender RC columns strengthened with longitudinal FRPs with a range of parameters, to a point that constructive and reliable recommendations can be made to fill the gaps of current design provisions regarding the FRP strengthening of slender RC columns. The results will be highly applicable for manufacturers and practicing engineers. The achievement of the research program not only will serve to elevate Canada to a leadership position in the area of structural rehabilitation, but also will seek innovative and sustainable solutions for the country's deteriorated infrastructure, such as bridges and water front structures with slender columns.

在过去的二十年中，纤维增强聚合物（FRP）复合材料作为具有优异特性的加固材料在土木工程中出现，用于修复现有钢筋混凝土（RC）结构。众所周知，垂直于 RC 柱轴线粘合单向 FRP（即缠绕）可以增加柱受压时的轴向承载能力。人们还认为，平行于RC柱轴线粘贴FRP只能增加其抗弯能力，而在轴向荷载作用下没有明显的加固效果。对于细长效果较低的短柱来说，情况确实如此。然而，对于长（细长）柱来说，情况完全不同，由于缺乏横向（弯曲）刚度，屈曲引起的失效可能会占主导地位。事实上，细长 RC 柱的强度是其细长度和由于其横向变形和轴向载荷引起的力矩的函数。因此，细长柱的弯曲刚度控制其轴向强度。该提案的创新之处以及与其他加固方法的主要区别在于，它主要通过粘合高模量纵向 FRP 来增强柱的弯曲刚度，从而寻求细长 RC 柱所需的加固增益。在本研究项目中，将主要在柱的纵向使用高模量FRP制备和加固大型细长RC柱，并将在实验室中进行低偏心轴向载荷下的测试。将研究圆形和方形横截面、长细比、初始荷载偏心率、FRP 比率、FRP 模量以及纵向和横向 FRP 组合的影响。此外，还将对可能影响纵向FRP性能的FRP破碎和脱粘失效力学进行深入研究。还将开发综合分析模型并根据实验数据进行验证，以研究各种横截面、边界条件、材料特性和纤维取向的影响。该研究项目完成后，预计将通过一系列参数对用纵向 FRP 加固的细长 RC 柱的性能进行量化，从而可以提出建设性且可靠的建议，以填补当前有关细长 RC 柱 FRP 加固的设计规定的空白。结果将非常适用于制造商和执业工程师。该研究计划的成果不仅将有助于提升加拿大在结构修复领域的领导地位，还将为该国破旧的基础设施（例如桥梁和细长柱的滨水结构）寻求创新和可持续的解决方案。