二维钢筋混凝土氯离子作用锈胀开裂数值模拟方法

Two-dimensional numerical simulation approach for corrosion and cracking of reinforced concrete induced by chloride

在环境氯离子作用下混凝土构件因钢筋锈胀产生开裂,导致结构耐久性退化。为模拟并研究这一过程,基于经典Fick定律建立了考虑温湿度、水灰比、氯离子浓度等的多因素氯离子扩散数值模拟方法。针对混凝土锈胀开裂,提出了基于二维格构式模型的钢筋混凝土锈胀开裂模拟方法,并建立了自由网格模型与格构式模型之间的钢筋表面锈胀节点力转换方法。基于上述方法针对某钢筋混凝土自然锈蚀试验进行数值模拟,与试验结果对比并验证本方法的可行性。最后,基于提出的方法研究钢筋位置、混凝土保护层厚度、钢筋直径对钢筋锈蚀及混凝土保护层锈胀裂缝宽度的影响。研究结果表明;角区钢筋锈蚀均大于边区钢筋;混凝土保护层厚度越大,钢筋锈蚀增长越缓慢;混凝土保护层裂缝宽度随钢筋直径增大而增加。

Chloride ions from atmospheric environment caused corrosion of rebar and cracking of reinforcement concrete,and furthermore result in degradation of durability.Anumerical simulation approach for simulation of this process considering temperature,humidity,water cement ratio,chloride ion concentration was introduced.For the purpose of simulating on concrete cracking induced by expansion of corroded rebar,anumerical method based on two-dimensional lattice model was established.Conversion law of nodal force between free mesh model and lattice model was proposed.A natural corrosion experiment on reinforced concrete beams was rebuilt and simulated by means of the methods proposed.Finally,the effects of rebar location,concrete cover,rebar diameter on the steel corrosion and concrete cracking were studied.The result showed corrosion rate of corner rebar was higher than middle rebar;corrosion rate decreased with thicker concrete cover;with increase of bar diameter,total crack width was enlarged.