大气环境下服役混凝土构件微环境温湿度响应规律及定量计算方法

The climate environment action is one of the most basic scientific problems in the researches on durability of concrete structures. Comparing with the traditional load action, the quantitative design and assessment for durability of concrete structures based on the quantification of climate environment action is a goal, which has not been completely achieved, but need to be achieved in the future. Based on the previous researches, this project mainly focuses on the effects of load on the microenvironment temperature and humidity responses of in-service concrete, in order to further approach the engineering practice. This project will start with analyzing the fundamental theories of heat and mass transfer of concrete. With the help of the testing method of artificially controlled simulation climate environment and the finite-element numerical simulation analysis, the microenvironment temperature and humidity response rules of concretes with various densities under the conditions of cracking caused by load are revealed, and their prediction models are also established. Finally, based on the action spectra of climate environment previously built by applicant and the above research results, the quantitative calculation method for the microenvironment temperature and humidity responses of concrete in atmospheric environment is presented considering the service conditions of members. In order to verify the feasibility of this method, the long-term experiment about microenvironment responses of concrete under load in atmospheric environment is carried out. The results of this project will provide the quantitative basis of environmental conditions for future researches on the durability problems such as concrete carbonation, chloride erosion, steel corrosion rate and others, and lay a foundation for the quantitative design of durability of concrete structures.

气候环境作用是混凝土结构耐久性研究中最为基础的科学问题之一。比照传统荷载作用问题，以气候环境作用定量化为基础的混凝土结构耐久性定量化设计与评估，是一个必须实现但又尚未完全实现的目标。本项目在前期研究工作基础上，进一步逼近工程实际，重点考虑服役状态下荷载效应对混凝土微环境温湿度响应的影响，拟从混凝土传热传质基本理论出发，利用人工控制模拟气候环境试验和计算机有限元数值模拟分析技术，揭示不同密实度混凝土在荷载开裂条件下的内部微环境温湿度响应规律，并建立预测模型；最后，基于申请人前期建立的气候环境作用谱和上述研究成果，提出大气环境下考虑构件服役状态的混凝土微环境温湿度响应定量计算方法，并通过开展大气环境下考虑荷载开裂的混凝土微环境响应长期试验，验证该方法的可行性。项目成果将为混凝土碳化、氯盐侵蚀和钢筋锈蚀速率等后续耐久性问题的研究提供定量的环境条件依据，为混凝土结构耐久性定量设计奠定基础。

气候环境作用是混凝土结构耐久性研究中最为基础的科学问题之一。比照传统荷载作用问题，以气候环境作用定量化为基础的混凝土结构耐久性定量化设计与评估，是一个必须实现但又尚未完全实现的目标。为此，项目开展了服役状态下荷载效应（应力和裂缝）对混凝土微环境温湿度响应的影响研究。项目的主要研究内容和成果如下：. （1）采用自制的应力加载装置，开展了人工控制恒定气候环境中不同荷载应力条件下的混凝土内部温湿度响应试验研究。研究结果表明：混凝土的温升响应速度随着压应力的增大而增快，随着拉应力的增大而减小；混凝土的湿度响应速度随着压应力的增大而降低，随着拉应力的增大而加快；混凝土水灰比较小时，拉应力对混凝土内部相对湿度响应的影响更显著，而水灰比较大时，压应力的影响更显著。提出了考虑应力影响的混凝土导热系数和等效湿气扩散系数预测模型。. （2）通过试验和ANSYS数值模拟的方法研究了表面裂缝对混凝土内部温湿度响应的影响规律。研究结果表明：裂缝宽度越大，混凝土内部温（湿）度响应越快；裂缝深度越大，混凝土内部温（湿）度响应越快。裂缝深度比裂缝宽度对温（湿）度响应的影响更显著；通过数值模拟分析了裂缝的影响范围。. （3）最后，基于上述研究成果和气候环境作用谱，初步提出了大气环境下考虑构件服役状态的混凝土微环境温湿度响应定量计算方法。项目成果将为混凝土碳化、氯盐侵蚀和钢筋锈蚀速率等后续耐久性问题的研究提供定量的环境条件依据，为混凝土结构耐久性定量设计奠定基础。