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利用5种钢纤维掺量活性粉末混凝土(RPC)圆柱形试件的SHPB冲击压缩实验研究了10×100~1.1×102s?1应变率范围内RPC的动态力学性能,分析了不同应变率和钢纤维掺量下RPC的应力波动特征、破坏模式、强度及耗能能力的变化规律以及应变率和钢纤维掺量的影响.提出了不同应变率和钢纤维掺量条件下RPC动态应力-应变响应的基本模式与本构模型.研究表明:应力波作用下素RPC的应力响应高于应变响应,脆性特征显著.掺入适量钢纤维后,RPC碎裂时的应变率和变形能力较素RPC有明显提高.相同钢纤维掺量下,应变率增加时,RPC的峰值抗压强度、峰值应变和残余应变均有不同程度的提高,其中残余应变提高的幅度最大.相同应变率条件下,提高钢纤维掺量对于改善RPC碎裂后的残余变形能力作用不大.钢纤维对RPC峰值抗压强度和峰值变形能力的影响不同,相同应变率下,钢纤维率不超过1.75%时,峰值抗压强度随纤维率增加而增加;纤维率超过1.75%后,峰值抗压强度开始逐步下降;峰值应变随钢纤维掺量增加而持续增大.相同应变率下,从冲击开始至残余变形阶段RPC的总耗能Edisp随钢纤维掺量增加而逐步提高,但纤维率超过2%后总耗能Edisp则开始逐步下降.不同变形阶段钢纤维对RPC耗能所起的作用不同.钢纤维率不超过2%时,钢纤维对提高峰值变形前耗能的作用大于对提高峰值变形后耗能的作用.应变率对总耗能和各阶段耗能均有显著影响,应变率越高,各阶段的耗能越大,动态冲击时的韧性越好.给出了RPC峰值抗压强度、峰值变形、残余变形,以及各阶段耗能随应变率和钢纤维率变化的经验模型.采用标准化的应力和应变作为广义应力与广义应变,以应变率和钢纤维率为界,将RPC的动态应力-应变响应模式简化为4类基本模型,并给出了每类模型的数学表达式.
The dynamic mechanical properties of RPC in the range of 10 × 100 ~ 1.1 × 102 s-1 were investigated by SHPB impact compression tests on five kinds of steel fiber reinforced reactive powder concrete (RPC) cylindrical specimens. The effects of different strain rates and steel The stress fluctuation characteristics, failure modes, strength and energy dissipation capacity of RPC at different fiber contents, as well as the influence of strain rate and steel fiber content, the dynamic stress-strain response of RPC under different strain rates and steel fiber content The results show that the stress response of the super-RPC is higher than that of the strain response and the brittleness is remarkable under the action of stress wave.Compared with the RPC The peak compressive strength, peak strain and residual strain of RPC all increased to some extent with the strain rate increasing, of which the residual strain increased most greatly.With the same strain rate, Fiber content for improving RPC rupture residual deformation capacity of little effect on the RPC peak compressive strength and peak deformation capacity of different, the same strain rate, the steel fiber rate does not exceed 1.7 5%, the peak compressive strength increases with the increase of the fiber ratio, while the peak compressive strength begins to decrease gradually when the fiber ratio exceeds 1.75%. The peak strain increases with the increase of the steel fiber content. Under the same strain rate, The total energy consumption Edisp of RPC increased gradually with the increase of steel fiber content from the beginning to the residual deformation stage, but the total energy loss Edisp began to decrease gradually when the fiber percentage exceeded 2. The effect of steel fiber on RPC energy dissipation during different deformation stages The effect of steel fiber on improving the energy consumption before peak deformation is greater than that on improving the energy consumption after peak deformation.The strain rate has a significant effect on the total energy consumption and the energy consumption in each stage, The higher the rate, the larger the energy consumption in each stage, the better the toughness during dynamic impact.The RPC compressive strength, peak deformation, residual deformation, and the energy dissipation in various stages with strain rate and steel fiber rate are given Model.Using the normalized stress and strain as generalized and generalized strain, the dynamic stress-strain response model of RPC is simplified into four basic models with strain rate and steel fiber rate as the boundary, and the mathematical expression.