混杂纤维增强应变硬化水泥基复合材料的拉伸本构关系

钢纤维与聚乙烯醇纤维混杂增强应变硬化水泥基复合材料(SF-PVA/SHCC)的力学性能研究是近年来的热点问题之一，但目前依然欠缺能够完整描述SF-PVA/SHCC拉伸本构关系的理论模型。本文基于混凝土断裂力学和细观力学理论，通过考虑拉伸应力-应变曲线软化段及SF-PVA混杂纤维对SHCC拉伸性能的影响，提出一种新的可适用于SF-PVA/SHCC材料的单轴拉伸本构模型。为了验证模型的有效性，开展了SF-PVA/SHCC单轴拉伸性能试验，分析了纤维种类和掺量对SHCC拉伸强度、拉伸应变及拉伸韧性的影响。通过与试验数据对比发现，本文所提出的拉伸本构模型可以较好地预测SF-PVA/SHCC的拉伸应力-应变关系。 

Tension constitutive relationship of hybrid fiber reinforced strain hardening cementitous composites

Mechanical properties of steel fiber hybrid polyvinyl alcohol fiber reinforced strain hardening cementitious composites (SF-PVA/SHCC) have been one of the hot topics in recent years. However, there is still a lack of the theoretical model that can fully describe the constitutive relationship of SF-PVA/SHCC in tension. Based on the theory of fracture mechanics and micromechanics of concrete, a new uniaxial tension constitutive model for SF-PVA/SHCC was proposed by considering the softening stage of stress-strain curve and the effect of SF-PVA hybrid fibers on the tensile properties of SHCC. In order to verify the effectiveness of the proposed model, a series of single-axial tensile tests for SF-PVA/SHCC were performed. The influence of fiber type and fiber content on the tensile strength, tensile strain and tensile toughness of SHCC was analyzed. Through the comparison with the experimental results, it was found that the proposed model could well predict the tensile stress-strain relationship of SF-PVA/SHCC composite.