海洋混凝土结构耐久性定量分析与设计

Quantitative analysis and design for durability of marine concrete structures

针对当前结构耐久性设计缺少定量计算模型,难以保证设计的混凝土结构在海洋环境腐蚀作用下达到预定服役寿命等问题,提出海洋混凝土结构耐久性设计的计算模型和定量设计方法。首先,利用试验数据和回归分析理论建立混凝土电通量与氯离子扩散系数的关系模型,分析验证该模型的合理性和适用性;进而选取混凝土保护层厚度、龄期衰减系数和氯离子渗透能力系数(混凝土电通量或氯离子扩散系数)等参数作为海洋混凝土结构耐久性设计参数,利用Fick第二定律建立耐久性设计参数的计算模型,提出海洋混凝土结构耐久性设计参数限值的确定方法和步骤,结合算例结果分析现行混凝土结构耐久性设计规范的局限性。研究表明,由于现行的混凝土结构耐久性设计规范所选取的设计参数中没有选取龄期衰减系数,且缺少定量计算模型,导致在部分情况下不能满足混凝土结构预定的服役寿命要求或混凝土制备要求。该文方法通过合理选取耐久性设计参数并依据定量计算模型确定设计参数限值,克服了现行设计规范存在的缺陷和不足。

This paper proposed a methodology of quantitative durability design for concrete structures in marine environment to overcome the limitation of current durability design codes. The relation model on chloride diffusion coefficient and charge passed was developed by regression analysis of the experimental data collected from references.The cover thickness,diffusion decay index and diffusion coefficient( or charge passed) of concrete were chosen as the basic parameters for durability design of concrete structures. The calculation model was presented based on the Fick's second law to determine the design values of the basic parameters. Two examples were employed to analyze the limitation of the current specification. Results shows that the design values of the basic parameters determined by the current design codes do not meet the requirement of service life of concrete structures under marine environment,since the diffusion decay index is not chosen as design parameter and cannot be determined in current design codes. This problem is solved satisfactorily by the quantitative durability design method presented in this paper.