混凝土结构耐久性控制区及设计参数的定量分析

Governing domain for durability of concrete structures and quantitative analysis of design parameters

现行规范的混凝土结构耐久性设计方法难以定量分析结构几何参数、环境作用等级、材料性能衰退等因素对结构服役寿命的影响。为此,针对氯化物腐蚀环境,提出了混凝土结构的耐久性控制区,并建立了混凝土结构耐久性设计参数的定量分析方法。首先基于混凝土中氯离子扩散补偿理论和结构几何外形建立混凝土结构的耐久性控制区模型;然后结合Fick第二定律,建立不同扩散维数下混凝土结构的耐久性定量分析模型,据此合理选取耐久性设计参数,并通过定量分析确定其取值。最后结合工程实例和设计规范对比验证了文中方法的有效性和适用性。研究表明,所提方法能够综合考虑混凝土结构几何外形及尺寸、环境作用等级、初始暴露龄期和材料性能衰退等因素对混凝土结构服役寿命的影响,可以有效克服现行规范耐久性设计方法中设计参数重复设置,不能有效反映材料性能衰退和结构几何外形的影响等不足。

Current durability design methods do not quantitatively take into account the effects of structural geometry, classification of environmental action and deterioration of material property on the specified service life of concrete structures. In order to solve this problem, the governing domain of durability was proposed and the quantitative analysis method was developed to determine the durability design parameters of concrete structures under chloride environment. The compensation theory of chloride diffusion was employed to define the governing domain of durability taking into account the geometry of concrete structures. The quantitative model for durability analysis of concrete structures under different dimensions of chloride diffusion was established by means of the Fick＇ s second law, based on which the durability design parameters were selected and determined quantitatively. The efficiency and applicability of the proposed method were verified by comparing with practical engineering structure and design code. Results show that the proposed method could overcome the disadvantages of current durability design methods such as overlapping of design parameters as well as ignoring influence of deterioration of material property and structural geometry, by taking into account the influences of structural geometry, classification of environmental action, curing time and deterioration of material properties on the service life of concrete structures.