单向受拉状态下的钢纤维混凝土本构模型

在混凝土中添加随机分布的钢纤维能有效提高混凝土力学性能。为了更好地考虑纤维对单向受拉状态下钢纤维混凝土（SFRC）的增强作用，提出一个钢纤维混凝土的弥散开裂本构模型。在弹性阶段，纤维混凝土被视为简单复合材料，基于两相复合材料理论，对SFRC的弹性刚度矩阵进行修正；在受拉开裂后，混凝土的塑性变形量被视为纤维与混凝土界面脱粘过程中滑移量，利用粘结滑移模型计算纤维在混凝土开裂面上的桥接作用。该文通过有限元软件ABAQUS中子程序二次开发接口Umat，进行Fortran编程，在ABAQUS中实现该本构模型。通过数值模拟结果与受拉实验数据进行对比，验证了该本构模型的准确性。通过数值模拟分析，进一步探究钢纤维混凝土相关参数对抗拉性能的影响，为钢纤维混凝土在实际的工程中的应用提供建议。

A CONSTITUTIVE MODEL OF STEEL FIBER REINFORCED CONCRETE UNDER UNIAXIAL TENSION

The addition of randomly distributed short fibers in plain concrete can significantly improve the tensile properties. A modified smeared crack constitutive model for steel fiber reinforced concrete (SFRC) is proposed for the simulation of the mechanical behavior under uniaxial loading. In this model, a two-phase composite law is introduced to modify the elastic stiffness matrix. When the tensile cracking occurs, the model considers the plastic deformation as the interfacial slip displacement on the fiber and employs the bond-slip model to simulate the fiber-bridging behavior on the crack surface. The constitutive model is achieved by a Fortran code in the user subroutine Umat of the finite element software ABAQUS. The comparison between the numerical simulation results and experimental data under uniaxial tension shows that the new model can be used to simulate the SFRC characteristic behavior with good accuracy. By the numerical simulations, we further explore the influence of the SFRC related parameters and provide suggestions for the SFRC practical applications.