超高性能混凝土弯拉与轴拉性能试验与有限元分析

Testing and Finite Element Analysis of Flexural and AxialTensile Properties of Ultra-high Performance Concrete

作为一种新型超高性能材料,超高性能混凝土(ultra-high performance concrete,UHPC)的力学性能研究得到国内外众多学者的关注。相比于普通混凝土,UHPC的巨大优势体现在抗拉性能方面,而关于UHPC抗拉性能的测试还没有较为成熟可靠的方法。因此制作了一组哑铃形试件和两组棱柱体试件,分别开展单轴拉伸和弯曲拉伸试验对UHPC的拉伸性能展开研究,结果发现,单轴拉伸试验的开裂应变约为200微应变,是普通混凝土的2倍;由于钢纤维的桥接作用,四点弯曲试验的初裂应力和弯曲强度比单轴拉伸试验的分别高了26.7%和96.2%;对单轴拉伸试验得到的应力-应变曲线进行拟合分析建立了UHPC抗拉应力-应变关系;在此基础上,结合混凝土损伤塑性模型建立了数值研究模型,以便于试验条件不足的情况下开展关于UHPC材料在大型构件中的研究。

The mechanical properties of ultra-high performance concrete(UHPC),as a novel ultra-high-performance material,have garnered significant attention from scholars globally.UHPC possesses a notable advantage over conventional concrete,primarily in terms of its tensile strength.Nevertheless,a mature and reliable method for testing the tensile properties of UHPC remains elusive.Consequently,dumbbell-shaped and prism specimens was fabricated for conducting uniaxial tension and flexural tension tests on UHPC,aiming to explore its tensile characteristics.The results reveal that the cracking strain in the uniaxial tension test amounts to approximately 200 microstrains,doubling that of ordinary concrete.Owing to the bridging effect of steel fibers,the initial cracking stress and flexural strength in the four-point bending test exceed those of the uniaxial tension test by 26.7%and 96.2%,respectively.A fitting analysis of the stress-strain curve from the uniaxial tension test delineates the tensile stress-strain relationship of UHPC.Subsequently,a numerical research model,coupled with a concrete damage plasticity model,is developed to aid in studying UHPC materials in large-scale components,particularly under limited experimental conditions.