FRP条带约束混凝土精细化非均匀轴压应力-应变本构模型实验研究

This research project aims to study the axial compressive behavior of FRP strip confined concrete by means of experimental study, theoretical analysis and numerical modeling on account of the fact that the strain distribution is non-uniform and the damage and failure mechanics are complicated in concrete confined with fiber reinforced polymer (FRP) strips. First of all, the damage and failure mechanics of FRP strip confined concrete, as well as the effects of clear spacing of FRP strips, concrete strength, thickness of FRP strips and FRP volumetric ratio are clarified by employing three-dimensional real-time strain and stress measurement techniques. Subsequently, the hardening rule and dilation rate are defined for concrete damage plasticity model in three-dimensional finite element modeling based on test stress-strain curves, with the limits for strong and weak confined concrete being identified. Additionally, refined constitutive model for FRP strip confined concrete is established by proposing a modified coefficient, with the size effect, FRP wrapping patterns and three-dimensional stress and strain distributions being carefully investigated. The outcome of the research project provides theoretical basis and decision support for safe design, applications and specification modification of FRP strip confined concrete.

针对FRP条带约束混凝土应变场的非均匀性及内部损伤-破坏的复杂性，本项目拟采用试验测试、理论分析与数值模拟相结合的方法，研究FRP条带约束混凝土的轴压力学性能。通过构建FRP条带约束混凝土三维动态应变、应力测试技术，揭示条带约束混凝土非均匀应力分布下损伤、断裂破坏机理。阐述FRP条带间隙比、核心混凝土强度、FRP条带层数、FRP体积配置率的影响规律。基于应力应变曲线实测模型，定义损伤混凝土的硬化准则及膨胀角变化规律，建立三维弹塑性损伤有限元分析模型，提出强、弱约束临界“门槛”变量。基于尺寸效应及持荷效应的影响规律，对比FRP螺旋连续粘贴方式以及方柱截面约束混凝土三向非均匀应力-应变分布，提出修正系数及修正方法，建立精细化FRP条带约束混凝土本构模型。本项目研究将为FRP条带约束混凝土结构的安全设计与应用以及相关规范的修正提供理论基础与决策支撑，具有重要的科学与工程意义。

针对FRP条带约束混凝土应变场的非均匀性及内部损伤-破坏的复杂性，本项目采用试验测试、理论分析与数值模拟相结合的方法，研究FRP条带约束混凝土的轴压力学性能。通过构建FRP条带约束混凝土三维动态应变、应力测试技术，揭示了条带约束混凝土非均匀应力分布下损伤、断裂破坏机理。阐述了FRP条带间隙比、核心混凝土强度、FRP条带层数、FRP体积配置率的影响规律。基于应力应变曲线实测模型，定义了损伤混凝土的硬化准则及膨胀角变化规律，建立了三维弹塑性损伤有限元分析模型，提出强、弱约束临界“门槛”变量。基于尺寸效应及持荷效应的影响规律，对比FRP螺旋连续粘贴方式以及方柱截面约束混凝土三向非均匀应力-应变分布，提出修正系数及修正方法，建立精细化FRP条带约束混凝土本构模型。本项目研究为FRP条带约束混凝土结构的安全设计与应用以及相关规范的修正提供理论基础与决策支撑，具有重要的科学与工程意义。