混凝土化学-力学耦合作用的非局部损伤模型

提出了混凝土化学损伤和力学损伤的耦合模型.用损伤变量表示的本构关系模拟混凝土力学性能.分析了化学侵蚀下混凝土损伤发展过程.研究表明,应力软化造成混凝土局部损伤是结构失效的根源.局部化学损伤出现的时候,平衡微分方程不能满足.为了解决这个问题,采用了非局部损伤模型.试验和有限元计算结果表明,混凝土化学-力学耦合作用的非局部损伤模型能够较好地描述受化学侵蚀与荷载共同作用的损伤状态.

NON-LOCAL DAMAGE MODEL OF CHEMICAL-MECHANICAL INTERACTION IN CONCRETE

The leaching of calcium ions in concrete pore solution by pure water usually results in deterioration of mechanicd behavior of concrete for the underground cement-based structures.The presentation of chemical attack leads to the loss of mechanical properties of the coucrete.In order to study the chemical and mechanical interaction,a non-local chemical-mechanical coupling damage model for the concrete is presented.The chemical attack follows a non-linear diffusion equation based on the mass conservation of the calcium ions in the concrete.The mechanical behavior of concrete is modeled according to a scalar damage constitutive relation.The influence of damage evolution on the chemical attack is analyzed.It is shown that local damage due to the strain softening is origin of the failure of the concrete structure.However when the chemical damage presents,the equilibrium differential equation can not be satisfied.A non-local damage model is implemented to solve the problem.Results of the test and finite element computation illustrate that the non-local damage model can describe the damage due to the chemical attack and the mechanical load.