钢-塑钢混杂纤维再生混凝土单轴压缩动态力学性能试验

Experiment on dynamic mechanical properties of steel and macro-polypropylene hybrid fibers reinforced recycled aggregate concrete under uniaxial compression

  • 摘要: 为探究钢-塑钢混杂纤维再生混凝土的压缩动态力学性能,设计了A、B和C 3个系列混杂纤维再生混凝土包含3种再生粗骨料取代率和5种体积分数1.5vol%的钢纤维和塑钢混掺纤维组合,采用了4种加载应变率。试验表明:随应变率增加,混杂纤维再生混凝土峰值应力、弹性模量和压缩韧性增大,峰值应变减小。相较于基准组,在相同应变率下3个系列中的含纤维组峰值应力最大增幅分别为23%、16%和16%;峰值应变最大增幅分别为19%、12%和13%;弹性模量最大增幅分别为15%、14%和35%;压缩韧性最大增幅分别为46%、32%和37%。在试验应变率范围内,再生粗骨料显著提高峰值应力、弹性模量和压缩韧性的应变率敏感性,对峰值应变的应变率敏感性并无明显影响;掺入纤维降低混凝土峰值应变和弹性模量的应变率敏感性,提高普通混凝土峰值应力和压缩韧性的应变率敏感性,降低再生混凝土峰值应力和压缩韧性的应变率敏感性。提出的动态损伤本构模型考虑了纤维增强系数、再生粗骨料取代率和应变率,计算结果与试验结果吻合较好。

     

    Abstract: The dynamic compressive behavior of hooked-end steel (HES) and macro-polypropylene (MPP) hybrid fibers reinforced recycled aggregate concrete (HyF/RAC) was studied. Three series (A, B and C) of HyF/RAC specimens were designed, which include three different recycled coarse aggregates (RCA) replacement ratios and five combinations of hybrid fibers at the total volume fraction of 1.5vol%, and four different strain rates were conducted. The results show that with the increase of strain rate, the peak stress, elastic modulus and compressive toughness increase, while the peak strain decreases. Compared with control groups in three series under the same strain rate, the largest increases of peak stress for specimens with fibers are 23%, 16% and 16%, respectively. The largest increases of peak strain are 19%, 12% and 13%, respectively. The largest increases of elastics modulus are 15%, 14% and 35%, respectively. The largest increases of compressive toughness are 46%, 32% and 37%, respectively. In the strain rate range, the strain rate sensitivity of peak stress, elastic modulus and compressive toughness increase with the RCA, and the RCA replacement ratio does not affect the strain rate sensitivity of peak strain. The strain rate sensitivity of peak strain and elastics modulus decrease with the addition of fiber. The addition of fibers enhances the strain rate sensitivity of peak stress and compressive toughness for natural aggregate concrete (NAC). While the strain rate sensitivity of peak stress and compressive toughness decrease for recycled aggregate concrete (RAC). The dynamic constitutive damage model was proposed considering the reinforcing index of fibers, RCA replacement ratio and strain rates. And all the models agree well with the experimental curves.

     

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