高温后高强高性能混凝土双轴压强度规律与破坏准则

利用大型静动真三轴试验机,进行了常温20℃和200℃―600℃高温后高强高性能混凝土在七种应力比α=σ2:σ3=0.00:-1,-0.20:-1,-0.30:-1,-0.40:-1,-0.50:-1,-0.75:-1,-1.00:-1,双轴压应力状态下的强度试验。单双轴压试件尺寸为100mm×100mm×100mm立方体,测得了双轴主压方向静态强度。剖析了温度和应力比对单轴、双轴压强度的影响规律性以及试件破坏形态。试验结果表明:高强高性能混凝土在200℃、300℃,其高温后单轴压减摩强度并不降低;二轴压强度相对于单轴压强度的提高倍数取决于应力比、不同温度等级高温后高强高性能混凝土的脆硬性。提出了高强高性能混凝土带有温度和应力比参数的Kupfer-Gerstle破坏准则公式。

STRENGTH AND FAILURE CRITERION OF PLAIN HIGH-STRENGTH HIGH-PERFORMANCE CONCRETE UNDER BIAXIAL COMPRESSION SURVIVING HIGH TEMPERATURES

This study attempts to investigate the strength behavior of plain high-strength high-performance concrete (HSHPC) subjected to biaxial compression load with seven stress ratios α=σ2﹕σ3 =0.00: -1,-0.20:-1,-0.30:-1,-0.40:-1,-0.50:-1,-0.75:-1,-1.00:-1.In the above cases, temperature loads are also applied, they are 20℃, 200℃, 300℃, 400℃, 500℃ and 600℃ respectively. Biaxial tests were carried out on 100mm×100mm×100mm cubic concrete specimens, then, the biaxial compression strengths were measured, and failure modes of specimens were inspected. Moreover, the influence of high temperature and stress ratio on the biaxial strength was also analyzed. Experimental results show that the uniaxial compression strength of plain HSHPC doesn’t decrease with the increasing of temperature at 200℃ and 300℃, and the ratio of the biaxial strength over uniaxial strength depends on stress ratio and brittleness-stiffness of HSHPC. Finally, the formula of the Kupfer-Gerstle failure criterion for plain HSHPC considering temperature and stress ratio is proposed.