新型拉挤多腔复材管-混凝土组合柱约束机理与受力性能研究

Fibre-Reinforced Polymer (FRP) tubes with multi-directional fibres which are manufactured by pultrusion process have excellent strength and modulus in the transverse direction, and could provide a higher confining force for the inside filler comparing with common pultruded FRP profiles. Innovative concrete-filled FRP tubes by filling concretes into multi-hollow sections of such multi-directional FRP tubes are proposed in this research project. Those concrete-filled FRP tubes could meet the urgent needs of mechanical property and durability of structural members in modern engineering projects, especially offshore engineering structure because of their advantages of good mechanical property and durability, various section patterns, non-formwork and suitability for sea-water or sea-sand concrete. .The mechanical mechanisms and design methods of concrete-filled pultruded multi-hollow-section FRP tubes with square or rectangular sections will be investigated, including: 1) confinement effectiveness and mechanism of pultruded multi-hollow-section FRP tube for concrete in it and design method of equivalent confinement ratio, 2) mechanical behaviors of bearing performance of pultruded multi-hollow-section FRP tube-concrete composite columns under compressive load with different eccentricities and the effects of equivalent confinement ratio and eccentricity, 3) analysis models of pultruded multi-hollow-section FRP tube-concrete composite columns which could include the effects of the complicated interaction between FRP tube and concrete, and 4) optimized section patterns of pultruded multi-hollow-section FRP tube and design method of the pultruded multi-hollow-section FRP tube-concrete composite columns.

基于多轴向纤维拉挤成型的新型复合材料管材，具有优异的横向强度及模量，解决了普通拉挤型材横向受力性能弱的问题，可对内部填充材料提供有效的横向约束力。将混凝土填充入该类型多腔复材管，可得到一种新型复合材料约束混凝土柱构件，其受力性能优异、截面灵活多样、耐久性好、施工无需模板、适用于海水/海砂混凝土，可满足现代工程、特别是沿海和海洋工程建设的迫切需求。.本课题以方形和矩形截面的新型拉挤多腔复材管-混凝土组合柱为对象，研究其在不同荷载工况下的受力机理和设计方法，包括：1）多腔复材管对内部混凝土的约束效应及机理，建立等效约束比的计算方法；2）多腔复材管-混凝土组合柱在不同偏心距荷载作用下的力学行为及承载性能，揭示等效约束比和偏心距的影响规律；3）建立可考虑多腔复材管与混凝土复杂相互作用的计算模型；4）提出合理的多腔复材管截面构型形式，并建立组合柱设计方法。

本项目提出一种多腔复合材料管-混凝土组合柱构件，其基本构成是采用复合材料拉挤型材形成多腔结构，然后在其中浇筑混凝土即可。其中复合材料多腔结构可采用拉挤工艺一体化成型，也可采用FRP包裹复合材料拉挤型材的方式制作。所采用的拉挤型材均为多轴向织物拉挤制作，具有优异的横向抗拉强度，可对内部的混凝土形成有效约束，从而提升该新型组合柱构件的受力性能和变形性能；由于组合柱内不含有金属构件，所以对腐蚀环境具有优异的抵抗性能，特别适用于海水海砂混凝土，在沿海和海洋工程建设中具有显著优势。.项目对FRP约束多腔复材管-混凝土组合方柱、FRP约束多腔钢管混凝土柱、内嵌FRP约束多腔钢管混凝土T形截面柱进行了轴压和偏压受力性能研究。共完成了57个不同类型的组合柱构件的加载试验，获得了其典型的力学行为和破坏模式，结果表明该新型组合柱均具有优异的受力性能。建立了可用于预测组合柱试件力学行为的数值模型，并基于模型进行参数分析，获得了FRP条带间隔、FRP层数、倒角半径、偏心距等关键参数对组合柱受力性能的影响规律。基于FRP约束混凝土分析理论，分别建立了不同类型组合柱力学模型，并推导了组合柱轴压和偏压承载力计算公式，可用于组合柱设计。