反映混凝土单边效应的弹塑性损伤本构模型及应用

为了尽可能有效和准确地描述混凝土材料的非线性力学特性，在研究国内外混凝土损伤本构模型的基础上，基于连续介质损伤力学和不可逆热力学的理论框架，采用统一强度理论作为屈服破坏准则，分别定义拉、压双标量损伤来考虑材料的拉、压迥异特性，同时引入反向加载影响因子以修正拉压交替循环加载时材料的单边效应，以及多轴应力状态下拉、压损伤累积的相互影响,最终采用显式积分算法建立了一种改进的混凝土弹塑性损伤本构模型.不同素混凝土加载试验模拟结果初步验证了建议模型的有效性，而通过对含I型裂缝的混凝土简支梁试验进行数值分析，结果表明，所得的荷载 挠度曲线与试验结果吻合良好，进一步检验了模型应用于结构非线性分析的有效性.

An Elastoplastic Damage Constitutive Model for Concrete Considering Unilateral Effects

In order to describe the nonlinear mechanical properties of concrete effectively and accurately, a new elastoplastic damage constitutive model for concrete was established with the explicit integration algorithm, under the theoretical framework of continuum damage mechanics and irreversible thermodynamics. First, a yield failure criterion based on the unified strength theory was employed for this model, and then 2 scalar damage variables were introduced to better describe the quite different tensile and compressive mechanisms of concrete, respectively. Besides, the influence factors of reverse loading were adopted in view of the unilateral effects under alternating cyclic loading conditions and the interaction effects of tension and compression damages in the multiaxial stress state. Several numerical simulations were presented, and good agreement was achieved between the numerical results and the test results for concrete specimens under uniaxial loading, multiaxial loading and alternating cyclic loading, which verifies the validity and accuracy of the proposed model.