纤维增强树脂复合材料约束超高性能混凝土轴压性能的细观数值模拟

Meso-scale numerical simulation of axial compression performance of fiber reinforced polymer composite-confined ultra-high performance concrete

利用LS-DYNA有限元分析软件建立纤维增强树脂(FRP)复合材料约束超高性能混凝土(UHPC)圆柱细观有限元模型,以研究其单轴受压性能。通过已有试验数据验证了模型的有效性,并建立了能准确反映FRP复合材料约束作用的K&C模型的剪切膨胀参数预测公式。在此基础上进行参数分析,研究FRP复合材料厚度、纤维缠绕角度和钢纤维掺量的影响。结果表明,本文模型不仅能模拟随机分布钢纤维对试件应力分布的影响,且能较准确反映FRP复合材料约束作用对核心UHPC强度和延性的提高效果。模型在轴压作用下的破坏模式和应力-应变曲线与试验结果基本一致。参数分析表明,随FRP复合材料厚度或纤维缠绕角度的增大,试件极限承载力和延性均增大,而增大钢纤维掺量虽可限制核心UHPC斜裂缝的开展,但对试件强度和延性影响较小。

To investigate the axial compressive performance of fiber reinforced polymer(FRP)composite-confined ultra-high performance concrete(UHPC)cylindrical specimens,the meso-scale finite element model was established in LS-DYNA and validated by the comparison of the experimental data.The formula of shear dilation parameter of K&C model was proposed,which could accurately reflect the FRP composites confinement for UHPC.Based on the validated model,a parametric analysis was conducted to investigate the influence of FRP composite tube thickness,FRP composites fiber winding angle and steel fiber content.The results show that the model can not only capture the effect of random distributed steel fibers on the specimen stress distribution,but also accurately reflect the enhancement of strength and ductility of UHPC core subjected to FRP composite confinement.Good agreement is found in failure modes and stress-strain curves between simulation and experimental results.Parametric studies show that with the increase of FRP composite tubes thickness and FRP composite fiber winding angle,the strength and ductility of the FRP composite-confined UHPC specimens are significantly enhanced.An increase in steel fiber content can effectively restrain the inclined shear cracks in UHPC core,but has little effect on the strength and ductility of the specimens.