单轴循环受拉条件下SP-HFRC力学性能试验研究

Mechanical Properities of Steel-polypropylene Hybrid Fiber Reinforced Concrete Under Uniaxial Cyclic Tension

通过对21个钢-聚丙烯混杂纤维混凝土(SP-HFRC)试件进行单轴循环受拉试验,研究SP-HFRC在循环受拉条件下的力学行为变化规律。重点分析混杂纤维体积掺量及长径比对应力-应变全曲线、累积塑性应变、刚度退化、应力退化的影响。结果表明:混杂纤维具有逐级阻裂作用使得SP-HFRC试件呈现明显延性破坏特征;应力-应变全曲线卸载点应变与塑性应变呈线性关系;SP-HFRC刚度退化过程随钢纤维体积掺量和长径比增加而减缓,受聚丙烯纤维体积掺量的影响不明显;纤维对应力退化率的影响不明显。在试验结果和相关文献试验数据的基础上,建立了SP-HFRC单轴循环受拉应力-应变全曲线方程,可用于结构非线性和滞回性能等的分析。

Through uniaxial cyclic tension tests on 21 steel-polypropylene hybrid fiber reinforced concrete(SP-HFRC)specimens,the mechanical behavior of SP-HFRC under cyclic tension was analyzed.The effects of steel fiber volume fraction,aspect ratio and polypropylene fiber volume fraction on the stress-strain curve,plastic strain,stiffness degradation and stress degradation were analyzed.The results show that hybrid fibers have progressive crack resistance,which makes the SP-HFRC specimens show obvious ductile failure characteristics.The relation of the envelope unloading strain and plastic strain is linear.Stiffness degradation process of concrete is alleviated by the increase of steel fiber volume fraction and aspect ratio,but is not affected obviously by the polypropylene fiber volume fraction.Steel fiber and polypropylene fiber show obvious positive mixing effects.Based on experimental results in current study and other literature,analytical equations are developed to generalize the monotonic and cyclic stress-strain responses of SP-HFRC,which can be used for the analysis of structural nonlinearity and hysteretic performance of SP-HFRC structures.