基于钢筋锈蚀耐久性的混凝土结构全寿命性能及设计理论研究

The performance degradation of concrete structure induced by reinforcement corrosion will affect its safety, applicability, economy and other requirements during structural life cycle. As to these structures, the durability design and its related integrated life cycle design are the developing trends to the structural design. Based on the research achievements obtained from the recently completed NSFC project, the corroded reinforced concrete structure will be chosen as research object, and its life cycle cost and design theory, which takes account of its integrated life stages of design, construction, operation, maintenance, failure and demolition, will be basically studied and applied. It mainly involves that, the durability test similarity theory of concrete structure in coupled actions of loads and aggressive environments, such as carbonation, chloride environments, will be put forward; and the evaluating index and similarity relationship of durability damage will be obtained. Then, based on the requirements of initial reliability level and operating performance, the structural durability limit states with different levels will be built and the model to predict its service life will be set up. Furthermore, an optimization relationship between structural initial design indexes and its further demands of maintenance and repair will be established by comparing its life cycle cost. Finally, by taking service life, structural performance and economic cost into account together, the analyzed and optimized methods for structural integrated life cycle design will be discussed and applied in real structures. Relevant research results could provide some references not only to the development of structural design theory, but also to the revision and improvement of related codes.

钢筋锈蚀引起的混凝土结构性能劣化将会影响到结构全寿命周期内的安全、适用、经济等要求。对该类结构进行耐久性设计，并将其纳入到结构全寿命设计理论中是发展趋势。本项目在申请人已有国家基金项目研究成果的基础上，选择锈蚀钢筋混凝土结构为研究对象，对其"设计、施工、运营维护、失效拆除"的全寿命周期成本以及设计理论进行基础科学与应用研究。主要包括：开展环境（碳化、氯盐环境）与荷载耦合作用下混凝土结构构件的耐久性试验相似理论研究，找出结构耐久性损伤的评价指标及相似关系；基于结构初始可靠度设计水平及使用性能要求，建立其耐久性极限状态的设置水准，提出寿命预测模型；通过全寿命周期成本的预测比较分析，建立结构初始设计性能与后期维修加固之间的优化平衡关系；以使用寿命、结构性能及经济成本为指标，探讨结构全寿命设计的分析与优化方法，并指导工程实践。相关研究成果可为混凝土结构设计理论的发展、相关规范的完善等提供参考。

本项目在国家自然科学基金委的资助下，主要开展了荷载与环境（氯盐和碳化环境）耦合作用下，钢筋混凝土构件耐久性相似试验及钢筋锈蚀引起的结构全寿命性能退化及设计理论等方面的试验研究与理论分析工作。主要成果有：1）在三点或四点受弯加载或自锚加载方式下，开展了26根钢筋混凝土长梁、5根预应力混凝土长梁以及48根钢筋混凝土短梁的耐久性侵蚀试验（包括人工气候模拟试验、自然侵蚀试验及通电加速试验）；其中，部分耐久性长期性能试验仍在进行当中。2）结合沿海混凝土工程的现场检测结果，分别研究了完好与开裂混凝土内氯离子的侵蚀行为、混凝土碳化行为以及钢筋锈蚀特性等相关耐久性分析参数的室内试验时间相似关系，给出了氯盐干湿循环作用下开裂混凝土的氯离子扩散系数、锈蚀钢筋力学性能的分析计算模型及有限元模型。3）结合结构适用与安全性要求，提出了钢筋临界锈蚀、保护层锈胀开裂以及承载能力退化失效等三层次耐久性水准；采用概率可靠度方法，建立了钢筋锈蚀条件下混凝土结构构件的全寿命性能时变可靠度分析与计算方法、耐久寿命预测方法。4）以钢筋锈蚀为背景，给出了混凝土结构全寿命周期内各阶段主要成本的计算分析方法；针对实际工程案例，重点探讨了结构运营期内不同维护措施、不同维护策略以及不同维护方法等条件下各种维护、维修以及修复加固成本的计算方法和效益-成本评价方法。5）以氯盐侵蚀环境下的混凝土桥梁构件为例，分析探讨了初始设计水平与后期维护加固成本之间的优化平衡关系，从结构耐久性角度给出了结构全寿命成本LCC的优化分析方法，初步提出了该类构件的全寿命设计理论框架。相关研究成果可为氯盐和碳化环境下混凝土结构构件的耐久性室内试验研究、锈蚀钢筋混凝土构件的力学性能评价以及结构全寿命性能与经济成本之间的内在关系分析等相关耐久性科学问题的研究提供了重要的参考，为该类环境下的混凝土结构耐久性设计规范的完善、结构全寿命设计理论的发展等提供一定的借鉴。