结构耐久性设计是针对拟建结构而言的,相对于拟建结构,既有结构已转化为现实的空间实体,环境条件也更为明确,这种根本性的转变使得既有结构的可靠性分析和评定具有其自身的特点,原设计采用的分析模型和参数可能不再适用于既有结构的可靠度分析。以混凝土保护层开裂作为耐久性寿命的终结标准,将混凝土立方体抗压强度与混凝土保护层厚度作为耐久性评定参数,结合混凝土结构服役期间的碳化深度与钢筋锈蚀深度的实测数据,研究了一般大气环境中既有混凝土结构的耐久性评定问题,提出了耐久性评定的接受准则,建立了基于可靠度的耐久性评定的实用方法,包括极限状态函数、剩余寿命评定表达式以及耐久性评定的分级原则,并通过算例说明了评定过程。该法为一般大气环境下既有混凝土结构的耐久性评定提供了参考。 Structural durability design is for the proposed structure, compared with the proposed structure, the existing structure has been transformed into a realistic space entity, the environmental conditions are also clearer. This fundamental change makes the reliability of the existing structure Analysis and evaluation have their own characteristics. The analysis model and parameters adopted by the original design may no longer be suitable for the reliability analysis of the existing structure. Taking the cracking of concrete protective layer as the end criterion of durability life, the compressive strength of concrete cubes and the thickness of concrete protective layer were taken as the evaluation parameters of durability. Based on the measured data of carbonation depth and steel corrosion depth during the service of concrete structure, The durability assessment of existing concrete structures in the environment is put forward, and the acceptance criteria of durability assessment are put forward. Practical methods of durability assessment based on reliability are established, including the limit state function, the expression of remaining life assessment and the classification of durability assessment Principle, and illustrates the evaluation process through an example. This method provides a reference for the assessment of the durability of existing concrete structures in the general atmospheric environment.