考虑参数空间变异性的氯盐环境下混凝土结构耐久性研究

由于混凝土材料性质的随机性，以及施工质量和局部环境等在空间上的差异，结构耐久性参数呈现出空间变异性，实际结构的损伤形态也体现出空间变化的特点。但在结构耐久性失效概率分析时，采用随机变量模型表征参数的不确定性，无法反映空间变异性的影响，与实际耐久性失效状态不符。由于参数的不确定性，基于可靠度的耐久性设计方法成为重要趋势。目前的研究通常把钢筋脱钝或发生适量锈蚀作为耐久性极限状态，但目标可靠度指标的选取缺乏充足的理论依据。针对这两个问题，本项目以氯盐环境下的典型混凝土构件为例，研究耐久性参数二维随机场的模拟方法，在此基础上研究考虑参数空间变异性的混凝土构件耐久性分析方法，并结合结构劣化的实际情况，提出合理的耐久性评估指标；最后通过建立全寿命性能水平与全寿命周期成本的关系，确定以钢筋脱钝作为极限状态进行耐久性设计时，基于设计使用年限的目标可靠度指标。

Spatial variability of durability parameters is evident due to the randomness of concrete property and the spatial difference of construction quality and local environment; As a result, the damage condition of actual concrete structures is characterized as spatial variability. However, the durability parameters are treated as random variables in durability reliability analysis, ignoring the effects of spatial variability, which results in the inconsistency of theoretical analyses and practical observations. Due to the existence of uncertainties associated with durability parameters, reliability-based durability design becomes the main tendency of development, in which the depassivation or minor corrosion of reinforcing steels is selected as the limit state, but the determination of corresponding reliability index is lack of evident theoretical support. Realizing these two problems, this project takes the concrete members under chloride ingress as examples, develops the method to model 2-dimensional stochastic field of durability parameters; and then establishes the framework for durability analysis of concrete members considering the spatial variability of parameters. Finally, the project investigates the relationships between the life-cycle performance and life-cycle cost of concrete members, so that the target reliability index is determined for the durability design of concrete member with given service life.