【作者】 王晓舟；

【导师】 金伟良；

【作者基本信息】 浙江大学 ， 结构工程， 2009， 博士

【摘要】 本文应用概率统计和模糊数学理论,从不确定性分析的角度对服役混凝土结构从材料、构件到结构的不同层次的耐久性评估方法进行了研究。以混凝土碳化、氯离子侵蚀引起的钢筋锈蚀、冻融作为混凝土结构劣化的主要环境作用因素,实现了以路径概率、层次分析等建模方法与信息更新、空间变异等分析思路的有效结合,为混凝土结构耐久性评估提供了新方法。本文主要进行了以下研究:1、基于现场检测试验与分析,探讨海港码头混凝土结构干湿交替区域氯离子侵蚀状况随高程、季节、材料及服役时间的变化关系,提出基于海域气象条件推定扩散模型参数,即表面氯离子浓度和扩散系数的新方法,并建立侵蚀严重区域高程范围与设计潮位之间的关系,可为海港码头混凝土结构耐久性设计、维护及现场取样工作提供参考依据。2、充分利用第三方结构参照物检测与室内快速实验结果的先验信息,初步确定性能预测模型参数,并通过少量结构原位测试和分析工作更新模型参数,实现混凝土结构耐久使用寿命的概率预测,提出了多环境时间相似(METS)理论与Bayes信息更新手段相结合的动态寿命预测新思路。3、基于混凝土锈胀开裂过程的随机性,提出了一种预测钢筋锈蚀程度、锈胀裂缝开展状况及承载力退化程度时变特性的路径概率模型,并编制了计算程序,能有效评估和预测氯离子侵蚀、混凝土碳化及两者耦合作用环境下钢筋锈蚀状况、锈胀裂缝宽度及构件承载力退化程度在不同时段的概率分布,实现了混凝土构件“有害物质侵蚀-钢筋锈蚀-混凝土开裂-钢筋锈蚀加剧-混凝土裂宽增大-构件承载力下降”的性能劣化全过程的数值模拟。经过多个工程实例验证,该模型是合理、有效的。4、以国内现有的冻融相似试验研究和工程调查资料为基础,经过统计分析提出了一种考虑多因素修正的适合混凝土抗冻耐久性环境区划设计与寿命预测的概率模型,成为混凝土抗冻寿命定量化设计和评估的可行方法。5、在现有等级模糊综合评判和层次分析理论的基础上,提出了一种改进的多层次混凝土桥梁耐久性评估模型。采用多因素决策的特征向量法、最优区间型隶属度函数、模糊扩张算法及权重均值技术等数学工具,编制了相应的评估程序,实现了对在役桥梁构件、构成及总体等各层次耐久性等级的综合评定,并结合基于锈胀开裂路径的混凝土构件耐久性能概率预测方法,实现了桥梁下部结构耐久性能等级退化规律的预测,可为决策者和工程师获得桥梁的系统判断和后续维修加固方案提供依据。6、为改进现有可靠度计算方法在评价构件或结构耐久性问题中存在的不足,将耐久性预测模型参数的空间变异性引入对混凝土结构性能劣化评估的概率预测模型中,计算获得构件服役期内的失效概率和混凝土表面钢筋锈蚀损伤、开裂和剥落面积比率等有效信息,为制定经济有效的维修策略提供参考。本文得到国家自然科学基金重点课题“氯盐侵蚀环境的混凝土结构耐久性设计与评估基础理论研究”(50538070)、国家高技术研究发展863计划“沿海重大混凝土桥梁耐久性试验方法与寿命评估技术”(2006AA04Z422)、交通部西部交通建设科技项目“混凝土桥梁耐久性指标体系、检测方法与评价标准的研究”(编号:200631822302-06)、浙江省科技计划项目“港口与海岸工程防腐蚀关键技术与配套设备的开发应用”(编号:2006C13090),中日(NSFC/JSPS)国际合作项目“基于全寿命管理的混凝土结构耐久性设计理论”等的资助,特此致谢。更多还原

【Abstract】 In this thesis,an improved and more realistic approach for durability assessment of existing reinforced concrete(RC) structure has been developed on the base of probability statistic and fuzzy mathematics method on material,component and system layer from uncertain point of view.Based on Bayesian updating and spatial variation, path probability method(PPM) and hierarchy analysis model are developed for durability assessment of existing RC structure,taking into account those effect of carbonation,chloride ingression induced reinforcement corrosion and frost damage as the major reasons of degradation of concrete structure.The research contents for durability assessment are as follows:1.An empirical method is developed to determine input parameters of diffusion model, which related to altitude,season,material and service time in wet-dry cycling zone of harbor RC structures.Surface chloride level and apparent diffusion coefficient indicating chloride ingression state can be predicted according to weather information of sea area,and also the relationship between seriously damaged area and design tidal level is suggested for design reference,maintenance and power sampling of harbor concrete structure.2.A dynamic way for service life prediction is established using multi-environmental time similarity(METS) and Bayesian updating technique.Inspection of third reference structure and indoor accelerated test are performed to find the similarity relationship between natural and artificially simulated climate environment.Prior information is acquired and updated by field test with several samples to realize the behavior and life evaluation of RC structure.3.A path probability model(PPM) is proposed to predict the stochastic corrosion-crack and load capability degradation process of RC structures with time. The time-dependent probability distribution of reinforcement corrosion ratio,crack width and reduced load capability of RC concrete in carbonation,chloride penetration or coupling-effect environment can be calculated effectively by computer program.Therefore it enable the simulation of the whole process from harmful mediums erosion,corrosion initiation of reinforcement,corrosion induced concrete crack,corrosion and crack propagation to load capability reduction.The result has been proved reasonable in engineering assessment cases.4.Based on previous similarity experiments and engineering investigation,a multi-effect modified probabilistic model is present to be utilized in quantitative design of frost resistance and assessment of concrete structure in durability environmental zonation design point of view.5.An improved multiple-layer fuzzy assessment model is proposed to evaluate the durability condition of existing reinforced concrete bridges.Taking advantages of optimal interval based membership function,extended fuzzy operation and fuzzy weighted average technique,a multi-attributive decision making approach with eigenvector/weight is adopted to give a more realistic representation of components and bridge condition rating by corresponding computer program.Furthermore,the degraded durability behavior of substructure in future is predicted with the help of corrosion-crack path based PPM method.The present methodology will help decision makers and bridge engineers to arrive at a systematic judgment and methodical steps toward maintenance or repair.6.The spatial variation of model parameters is introduced as a supplement to current reliability analysis method in evaluating components or structures.The improved approach can produce not only the probability of failure but also the useful information as the proportion of surface area with initiation of rebar corrosion, cracking and spalling,etc.during the whole period of time that facilitates the repair or maintenance strategies for concrete structure from economical point of view.This research was supported by the project of National Natural Science Fund "Fundamental Research on Durability Design and Assessment of Concrete Structures in Chloride Erosive Environment"(50538070),863 program of National Hi-Tech Research Development "Durability Test Method and Assessment Technology of Important Coastal bridges"(2006AA04Z422),the West Traffic Construction Project of National Traffic Ministry "Study on Durability Index System,Test Methodology and Assessment Standard of Concrete Bridges"(200631822302-06),the science and technology project of Zhejiang Province "Key Anti-corrosion Techniques of Harbor and Costal Engineering and Development and Application of Supporting Facilities" (2006C13090),the agreement project of Chinese and Japanese(NSFC/JSPS) "Durability design theory of concrete structure based on Life-Cycle Cost Management Technique".Their support is gratefully acknowledged.更多还原