考虑应力状态的二维混凝土碳化过程数值模拟

混凝土碳化过程的数值模拟为研究碳化机理、碳化影响因素、碳化过程与力的耦合作用等提供了新的定量分析工具.为定量分析应力状态对混凝土截面角部碳化发展的影响,建立了混凝土碳化过程的2维数值计算模型,使得混凝土组分、应力状态等影响可以得到定量考虑,并模拟应力状态下混凝土构件角部的碳化过程.详细介绍了这一模型的数值计算实现过程,研究了网格尺寸及时间步长对数值计算结果的影响.该模型数值计算结果与快速碳化试验和长期暴露碳化试验结果的对比验证了模型计算结果的准确性.最后,对某混凝土构件的角部混凝土碳化过程进行了数值分析.结果表明,混凝土截面角部双向碳化作用以及拉应力状态均会加速混凝土碳化,角部是整个构件截面碳化发展最为迅速的部位,其耐久性应当予以考虑.

Two-Dimensional Numerical Simulation of Carbonation Process Considering Stress State

Numerical simulation provides a new way for concrete carbonation research, both for mechanism and engineering application. In order to quantitatively evaluate effect of carbonation process of concrete section corner under stress state, this paper presents a two dimensional (2D) numerical model of carbonation process, which takes account of the effects of concrete composition and stress state. The process to develop the numerical program is also introduced, the effects of element size and time step are discussed. The numerical program is verified by comparing calculation results with some existing carbonation experiments results, which turns out a good coincide. Finally, an example is used to illustrate the effect of stress state on the carbonation process of concrete section corner. The results show that the carbonation rate in the corner of concrete section is faster than others due to acceleration effects of the two dimensional diffusion of carbon dioxide into concrete and tension stress state, and attention should be paid to the durability of concrete section corner.