【摘要】 荷载作用下材料性能的劣化是混凝土结构的微观损伤机理,其宏观表现为结构刚度的折减和承载力的降低。论文推导了基于不可逆热力学过程的弹塑性标量损伤本构,给出时间离散的屈服准则。采用基于向后Euler法的应力更新算法——两步图形返回的最近点投影法,推导了满足迭代结果收敛假设的塑性参数及算法刚度张量,给出了空间梁单元本构积分算法的Jacobi矩阵。将模型用于混凝土简支梁的承载力试验模拟,与计算数据对比表明了模型和算法的合理性和有效性。更多还原

【Abstract】 Degradation of material properties could be considered as the micro damage mechanism of concrete structures,which introduces the macro behaviors of structures with stiffness delimitation and bearing loss of the system.In this essay,the authors derived one kind of scalar damage constitutive model based on the irreversible thermodynamics.The yielding criterion was expressed in time-discretization formulation.The two-step map returning method(closest point projection method) based upon implicit backward Euler scheme was obtained according to the stress upgrade algorithm.The plastic parameter and the consistent tangent stiffness tensor were deduced which meet the convergent supposition.The constitutive integral Jacobi matrix of a 3D beam element was listed at the same time.Then a simple-supported concrete beam under monotonic loading was simulated according to the previous damage model.Comparison between the experiment results and simulation solution indicates the validity and rationality of the model and framework described beforehand.更多还原