【作者】 刘顶平；

【导师】 王利民；

【作者基本信息】 山东理工大学 ， 工程力学， 2011， 硕士

【摘要】 纤维增强复合材料(FRP)具有轻质高强、比模量低、耐腐蚀等良好的力学性能,尤其碳纤维(CFRP)和玻璃纤维(GFRP)性能更为优越,将其用于修复混凝土结构已经成为目前应用最为广泛的加固技术。本文测试了纤维布及混凝土的力学性能,通过实验研究FRP加固混凝土梁的破坏行为,并进行有限元仿真,分析了影响FRP加固混凝土构件效果的因素,并进一步探究其破坏机理,为实际工程设计提供理论依据。材料性能试验分为3组,一组为纤维布试件,通过轴向拉伸实验测定其抗拉强度,弹性模量及泊松比；第二组为圆柱体混凝土轴压试件,通过轴向压缩实验测定混凝土抗压强度及其弹性模量；第三组为混凝土拉伸件,通过轴向拉伸实验测定其抗拉强度、抗拉弹性模量及泊松比。纤维布加固梁试验研究分2组,一组为550x100×123mm的素混凝土梁,共有12根梁,其中有4根未加固混凝土梁,4根粘贴两层长250mmGFRP的加固梁、4根粘贴两层长475mmGFRP加固梁。对上述试件进行三点弯曲加载试验；另一组为1800×120×200mm的钢筋混凝土梁,共计5根梁,先进行四点弯曲试验使其破坏。然后根据破坏形式粘贴CFRP纤维布,再进行四点弯曲实验。主要研究了加固梁的破坏特征、极限荷载、最大挠度、中性层位移、纤维板的应力分布及粘贴形式对加固效果的影响。结果表明,FRP加固后梁的承载力和抗弯刚度得到显著提高,延性却有所降低,可以通过增加纤维布的长度来改善这种缺陷。FRP加固可以有效改善梁底裂缝的分布形态,且对其中性层的位移有明显影响。为优化加固方式,本文采用大型有限元分析软件ANSYS对普通混凝土梁和GFRP加固混凝土梁进行非线性有限元分析,通过选取合理的单元和本构模型,进行有限元分析,分析结果和实验结果吻合良好。更多还原

【Abstract】 Fiber reinforced polymer (FRP) has such good mechanical properties as little weight, high strength, high elastic modulus, and strong corrosion resistance, and carbon fiber (CFRP) and glass fiber (GFRP) which especially have better such properties can be used in the repairing of the concrete structure. Currently, this technique has become the most widely used reinforcement technique.In this paper, we tested the mechanical properties of concrete and FRP, experimentally studied the damage behavior of concrete beams reinforced by FRP and calculated the experimental data by finite element simulation. Meanwhile, we analyzed the influencing factors of the effects of reinforcing concrete beams by FRP and further investigated the mechanism of the damage behavior, which can provide theoretical basis for practical engineering design.The material performance experiments were divided into three groups; in the first group, the tensile strength, elasticity modulus and poisson ratio of fiber cloth, the only specimen in this group, were tested by the axial tensile experiment; in the second group, the tensile strength and elasticity modulus of concrete axial compressive specimens were tested by axial compression experiment; in the last group, the tensile strength, elasticity modulus and poisson ratio of tensile specimens of concretes were tested by the axial tensile experiment.The experimental research of FRP reinforced beam are divided into two groups, one group consisted of 12 concrete beams with the size 550 x 100 x 123mm, four of which were not reinforced, four of which were pasted two layers of 250mm GFRP, four of which were pasted two layers of 475mm GFRP. The three-point bending beam test was performed on the specimens in this group; in the other group, total 5 reinforced concrete beams with the size 1800 x 120 x 200mm were damaged by four-point bending experiment. Then the test was performed again after CFRP fiber cloth was pasted on them. The experiment mainly studied how such factors as the failure characteristics, the limit load, the largest deflection and the displacement of neutral layer of the reinforcing beam, and the stress distribution and the form of pasting FRP of the fiber board influenced the reinforcing effect. The research results indicate that the bearing capacity and flexural stiffness of reinforced beam were markedly improved. However, its ductility was reduced, but this defect can be improved by increasing the length of FRP. Pasting FRP can effectively improve the distribution shape of cracks in the beam and had obvious influence on the displacement of neutral layer. To optimize the method of reinforcement, in this paper we made nonlinear finite element analysis of the limit bearing capacity of the ordinary concrete and the concrete beams reinforced with GFRP by finite element software ANSYS. By selecting the suitable unit and constitutive model we analyzed the data, and the results coincide well with the experimental results.更多还原