兼顾适用性和安全性的混凝土结构耐久性设计方法研究

针对重大工程或使用年限超长的混凝土结构，基于可靠度的定量化耐久性设计通常以钢筋脱钝作为极限状态，无法反映结构全寿命期间适用性和安全性的劣化情况，导致结构的长期性能得不到保障，存在结构失效的风险。因此，如何在耐久性设计中兼顾到适用性和安全性的变化，保证其满足寿命要求，便成了一个重要问题。现有耐久性分析模型都是在“材料”层次上建立的，而适用性和安全性反映的是“构件”能否满足正常使用和承载要求。因此在构件层次上分析混凝土结构的性能劣化，便成了一个亟需解决的关键问题。本项目以氯盐环境下的典型混凝土构件为例，利用二维随机场的数值模拟，研究构件层次上的基于机理的混凝土结构表观劣化模型和承载力衰减模型。在此基础上，利用结构时变可靠度理论，研究材料层次的耐久性设计标准对结构适用性、安全性劣化程度的影响。最后，通过考虑现实可行的维护策略，建立针对不同使用年限、兼顾适用性和安全性的混凝土结构耐久性设计方法。

For the durability design of important projects or super-long RC structures, reliability-based quantitative method is needed, in which the limit state is defined as steel de-passivation. It cannot account for the deterioration of serviceability and safety of structures during the whole service life, and results in the long-term performance being out of control. Therefore, it is important for structural durability design to account for the variation of serviceability and safety of structures with time. Existing durability analysis models are at “material” level, while serviceability and safety describe whether a structural “member” satisfies service and loading requirements. Thus, a durability model at “member” level becomes an urgent need. This project takes typical members at chloride environment as research objects, and implores mechanism-based surface deterioration models and resistance deterioration model by means of 2D random field modelling. And then, the project investigates the impact of durability design level on structural serviceability and safety based on time-dependent reliability theory. So that, a durability design methodology is established, which considers the choice of maintenance strategy and different service life, and accounts for the variation of serviceability and safety over the entire life.