混杂纤维超高性能混凝土力学性能尺寸效应

Size Effect of Mechanical Properties of Hybrid Fiber Ultra-high Performance Concrete

为研究钢-聚丙烯混杂纤维超高性能混凝土(HF‑UHPC)的力学性能尺寸效应规律,考虑纤维参数的影响,对不同尺寸HF‑UHPC试件开展立方体抗压强度和轴心受压力学性能试验.结果表明:随着钢纤维掺量和钢纤维长径比的增加,试件立方体抗压强度、轴心抗压强度和轴心受压峰值应变的尺寸效应更加显著;随着聚丙烯纤维掺量的增加,试件立方体抗压强度、轴心抗压强度和轴心受压峰值应变的尺寸效应变化幅度较小,呈现先减后增趋势;试件弹性模量的尺寸效应受混杂纤维参数影响很小,可忽略不计.此外,基于试验结果揭示了试件抗压强度尺寸效应产生机理,并建立了试件抗压强度尺寸效应律参数的计算公式,可用于不同尺寸试件的抗压强度计算.

To study the size effect of mechanical properties of steel‑polypropylene hybrid fiber ultra‑high performance concrete(HF‑UHPC),the cube compressive strength and axial compression mechanical properties of HF‑UHPC specimens with different sizes were studied by considering the influence of fiber parameters.The results show that the size effect of cube compressive strength,axial compressive strength and axial compression peak strain of the specimen becomes more significant with the increase of steel fiber content and length‑to‑diameter ratio.With the increase of polypropylene fiber content,the size effect of cube compressive strength,axial compressive strength and axial compression peak strain of the specimen changes slightly,showing a trend of weakening at first and then increasing;The size effect of elastic modulus is little influenced by the parameters of hybrid fibers,and it can be ignored.In addition,based on the experimental results,the mechanism of size effect of compressive strength of the specimen is revealed,and the calculation formula of size effect law parameters of compressive strength of the specimen is established,which can be used to calculate compressive strength of the specimen with different sizes.