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通过约束再生混凝土单轴受压动态力学试验,研究了应变率效应对约束再生混凝土力学参数的影响.分析不同应变率下再生混凝土动态破坏特征以及受压应力-应变关系全曲线,可以发现:在不同应变率、再生粗骨料取代率或体积配箍率下,再生混凝土单轴应力-应变关系曲线的上升段基本一致,而下降段差异较为明显;随着应变率的提高或再生粗骨料取代率的增加,下降段曲线随之变陡,而随着箍筋配箍率的提高,下降段曲线明显随之趋于平缓.通过试验数据回归分析,提出约束再生混凝土受压峰值应力和峰值应变动态放大系数函数模型;随着应变率的提高,约束再生混凝土受压峰值应力和峰值应变均随之增大;而约束再生混凝土受压峰值应变动态放大系数增加幅值低于受压峰值应力动态放大系数的增加幅值;进一步分析了应变率效应对约束再生混凝土初始弹性模量的影响规律,确定了初始弹性模量和应变率的函数关系,并给出了初始弹性模量动态放大系数函数模型.随着应变率的提高,约束再生混凝土初始弹性模量动态放大系数随之增大,但其增长幅度要比受压峰值应力和峰值应变动态放大系数的增长幅度小.
The effect of strain rate on the mechanical properties of constrained recycled concrete was studied by dynamic mechanical tests of restrained recycled concrete under uniaxial compression.Analysis of dynamic failure characteristics and compressive stress-strain curves of recycled concrete at different strain rates showed that in Under the condition of different strain rate, replacement ratio of recycled coarse aggregate or volumetric curtailment ratio, the rising section of uniaxial stress-strain curve of recycled concrete is basically the same, but the difference of descending section is obvious. With the increase of strain rate or the regeneration of coarse aggregate With the increase of the stirrup ratio, the curve of the descending section tends to be gentle. By regression analysis of experimental data, the compressive peak stress and peak value of the confined recycled concrete With the increase of strain rate, the compressive peak stress and peak strain of constrained recycled concrete both increase, while the increase amplitude of dynamic amplification factor of confined recycled concrete under compressive stress is lower than that of compressive peak stress Dynamic amplifying coefficient increased amplitude; Further analysis of the effect of strain rate on the initial elastic modulus of constrained recycled concrete shadow Law, the initial elastic modulus and the strain rate function were determined, and the dynamic amplification coefficient function model of the initial elastic modulus was given. With the increase of the strain rate, the dynamic amplification coefficient of initial elastic modulus of constrained recycled concrete increased , But its growth rate is smaller than that of the dynamic amplification factor of peak stress and peak strain.