高温后高强高性能混凝土双轴压力学性能

利用大型静动真三轴试验机，进行了常温20${^\circ}$C以及200${^\circ}$C$\sim $ 600${^\circ}$C\,6个温度等级高温后高强高性能混凝土在7种应力比双轴压应力状态下的强度与变形试验.测得了双轴主压方向的静态强度、峰值应变与应力应变曲线，剖析了温度和应力比对单、双轴压强度与峰值应变发展趋势的影响规律性以及试件破坏形态. 试验结果表明:随温度的升高，高强高性能混凝土的单轴压减摩强度并不一定降低；双轴压强度相对于单轴压强度的提高倍数取决于应力比、不同温度等级后的高强高性能混凝土``脆硬性'. 提出了带有温度和应力比参数的Kupfer-Gerstle破坏准则公式. 

MECHANICAL PROPERTIES OF PLAIN HIGH-STRENGTH HIGH-PERFORMANCE CONCRETE UNDER BIAXIAL COMPRESSION AFTER EXPOSURE TO HIGH TEMPERATURES

This study aims to generate the mechanical response of plain high-strength high-performance concrete (HSHPC) subjected to biaxial compressive loading at seven stress ratios, $\alpha = \sigma _{2} : \sigma_{ 3}, $-0.00: -1, -0.20: -1, -0.30: -1, -0.40: -1, -0.50: -1, -0.75: -1, -1.00: -1$, after exposure to the temperature of 20${^\circ}$C, 200${^\circ}$C, 300${^\circ}$C, 400${^\circ}$C, 500${^\circ}$C and 600${^\circ}$C, using the true-triaxial loading system. The biaxial static compressive strengths, strains at the peak stress and the stress-strain curves are obtained to analyze the influence of the temperature and the stress ratio. Failure modes of plain HSHPC specimens are observed. The experimental results show that the biaxial compressive strength of HSHPC is more sensitive to the stress ratio and the exposure treatment to high temperatures than the uniaxial compressive strength. The Kupfer-Gerstle failure criterion for plain HSHPC is developed with the parameters of the temperature and stress ratio.