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: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=664029
• 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，纤维增强的聚合物（FRP）复合材料已经在土木工程中出现，作为增强材料具有较高特征的材料，以恢复现有的钢筋混凝土（RC）结构。众所周知，垂直于RC柱轴（即包装）的单向FRP键合FRP可以增加压缩柱的轴向负载能力。还可以接受的是，与RC柱轴平行的FRP键只能增加其弯曲能力，而不会在轴向载荷下显着强大效果。对于较小效果低的短列是正确的。但是，对于长期（细长）的列，故事完全不同，由于缺乏横向（弯曲）刚度，屈曲引起的失败可以控制。实际上，由于其横向变形和轴向负载，细长的RC柱的强度是其细长和诱导力矩的函数。结果，细长柱的弯曲刚度控制其轴向强度。该提案的创新方面以及与其他强化方法的关键区别在于，它主要通过通过粘结高模数纵向FRP来提高柱子的弯曲刚度，从而寻求所需的增强增益。在该研究计划中，将使用主要沿柱的纵向方向进行大规模细长的RC色谱柱进行准备和加强，并将在实验室中测试，在偏心率低的轴向载荷下。将研究圆形和方形横截面，细长比率，初始载荷偏心率，FRP比，FRP模量以及纵向和横向FRP的组合的影响。此外，将对可能影响纵向FRP的性能的FRP碎屑和脱键失败的力学进行深入研究。还将针对实验数据开发和验证全面的分析建模，以研究广泛的横截面，边界条件，材料特性和纤维方向的影响。该研究计划完成后，预计将量化具有一系列参数的纵向RC列的行为，以至于可以提出建设性和可靠的建议，以填补有关较细长RC列的FRP的当前设计规定的空白。结果将非常适用于制造商和执业工程师。该研究计划的实现不仅将使加拿大在结构康复领域的领域提高领导地位，而且还将为该国的基础设施不断变质寻求创新和可持续的解决方案，例如带有细长柱的桥梁和水面结构。