混凝土高温力学性能研究是工程结构抗火分析和安全性设计的基石。本项目从国家优秀青年基金的科研成果出发，进一步深入研究高温、多场耦合条件下混凝土的本构关系及剥落爆裂机理。考虑细观各相组分的相互作用，提出混凝土高温力学行为的细观物理本构模型，系统研究混凝土的高温损伤机制和具有明确物理意义的损伤演化法则，建立合理反映细观非均质特性的混凝土高温损伤本构理论；探究混凝土高温力学行为与湿-热传输过程的耦合规律，客观描述受拉局部损伤的重要影响，发展面向混凝土高温剥落爆裂的多场耦合分析方法，研究提出控制方程的高效求解算法并进行数值实现。为了充分验证上述研究成果，设计并开展混凝土构件的高温明火试验；有机结合数值模拟与试验研究，综合分析不同要素下混凝土受拉局部损伤的分布和变化规律，科学揭示高温剥落爆裂的物理机理并提出合理的预测准则，为基于性能的混凝土结构抗火分析、设计及安全评估提供重要理论基础和关键技术支撑。

The mechanical properties of concrete exposed to high temperature is the fundamental basis of fire-resistance analysis and safety design of engineering structures. Based on the research achievements from previous projects supported by the National Natural Science Foundation of China, the constitutive model and mechanisms responsible for the progressive/explosive spalling of concrete under high temperature and multi-physics coupled-field are to be further studied in this project...With the interactions between mesoscopic constituents of concrete consistently accounted for, a physical constitutive model is first proposed for the modeling of high temperature mechanical behavior. The damage mechanisms and evolution laws with well-defined physical interpretations are systematically investigated. The damage constitutive theory with the mesoscopic heterogeneities appropriately incorporated is then established for concrete exposed to high temperature...The coupling laws between the mechanical behavior of concrete and the transport of moisture/heat under high temperature are thoroughly explored and the significant influences of tensile localized damage are consistently considered. The coupled hygro-thermo-chemo-mechanical method is then developed, oriented for the prediction of progressive/explosive spalling of concrete exposed to high temperature. The numerical algorithm of high-efficiency is put forward for solving the governing partial differential equations and implemented in finite element software packages...To fully validate and verify the above theoretical and numerical achievements, two series of plain and reinforced concrete members are elaborately designed and experimentally tested under fire scenarios. By integrating the results obtained from both numerical simulations and experimental studies, the distribution and evolution laws of the tensile localized damage in concrete exposed to high temperature are comprehensively analyzed. The physical mechanisms responsible for the progressive/explosive spalling of concrete are then scientifically discovered, resulting eventually in a novel predictive criterion. ..The above research achievements provide important theoretical basis and key technical support for the performance-based analysis, design and safety assessment of concrete structures under high temperature like fire scenarios.