受火灾作用的活性粉末混凝土梁斜截面破坏机理与承载性能研究

Green ultra-high performance concrete - Reactive Powder Concrete (RPC) is a new building material with great prospect. In view of the fire safety of RPC beam with oblique section, this project is studied by experimental research, theoretical analysis and numerical calculation. Firstly, shear bearing performance of RPC beams under fire will be studied, explosive spalling mechanism under a high heating rate in shear bending section will be reveal, and then control method of RPC explosive spalling will be developed. Based on fine researching the shear failure mechanism and shear bearing damage, the calculation method of fire resistance will be proposed. Secondly, the shear bearing performance of RPC damage beam after fire will be studued Shear transfer mechanism, deformation characteristics, crack development rule and failure mode will be obtained from experiment, and the theory for calculating the residual shear bearing capacity of RPC beam will be established. Finally,based on the effect of load characteristics and end constraints on the fire resistance of RPC beams under shear condition, a fire safety control theory based on structural system for RPC beam oblique section loading will be proposed, and a performance-based design method that no explosive spalling and no collapse in fire, well repairing after fire will be put forward. This project will enrich and develop the theory of fire resistance for ultra-high performance concrete, and provide scientific and technological support for ensuring the safety of RPC beam under shear conditions. It has important scientific and practical value.

绿色超高性能混凝土-活性粉末混凝土（RPC）是极具应用前景的新型建材。鉴于RPC梁斜截面承载的火灾安全性亟待研究探明，本项目以试验研究、理论分析和数值计算为手段，首先，研究火灾下RPC梁斜截面承载性能，揭示高升温速率下剪弯段RPC爆裂机理，发展RPC爆裂的控制方法，并摸清火灾下RPC梁斜截面破坏机理和承载性能损伤演化规律，提出耐火极限计算方法；其次，研究受火损伤后RPC梁斜截面承载性能，揭示其剪力传递机制，分析并掌握变形特征、裂缝发展规律和破坏形态，发展斜截面剩余承载力计算理论与方法；最后，研究荷载特性、端部约束对RPC梁斜截面抗火性能的影响，建立基于结构体系的RPC梁斜截面承载的火灾安全控制理论，提出火灾时不爆裂、火灾下不坍塌、火灾后可修复的性能化设计方法。本项目研究将丰富和发展超高性能混凝土抗火理论，为保障RPC梁斜截面承载的火灾安全提供科学和技术支撑，具有重要的科学意义和实用价值。

活性粉末混凝土（RPC）是极具应用前景的新型绿色低碳建材。本项目针对受火灾作用的活性粉末混凝土梁斜截面破坏机理与承载性能开展研究。通过试验研究和理论分析，揭示了火灾下RPC爆裂机理，探明了火灾下RPC梁斜截面受剪损伤演化过程和承载性能，摸清了火灾后RPC梁斜截面剪力传递机制和破坏模式，建立了RPC梁斜截面抗火设计方法。主要完成了如下5方面研究工作。.（1）开展了RPC爆裂试验，揭示了RPC高温爆裂机理，探明了蒸汽压力对RPC爆裂的主导作用，提出了分阶段干热养护消除蒸汽压力、纤维抵抗热应力的爆裂防控方法，实现了高升温速率、高应力状态下RPC爆裂完全防控。.（2）开展了RPC梁斜截面受剪静载试验，获得了斜截面失效机理与损伤演化规律，研究表明现行设计规范计算相对保守，提出了RPC梁受剪承载力计算方法。.（3）开展了RPC梁斜截面承载的火灾试验和理论分析，揭示了火灾下斜截面承载性能的关键影响因素（剪跨比、箍筋配置）及影响规律，研究了箍筋配置对剪力传递机制受火损伤的控制效果，提出了RPC梁火灾下斜截面受剪承载力计算方法。.（4）开展了火灾后RPC梁斜截面承载性能试验与分析，厘清了关键参数（受火时间、箍筋配置、剪跨比）及其对剪力传递机制失效模式和受剪承载性能的影响规律，建立火灾后RPC梁剩余受剪承载力计算方法。.（5）研究了间接加载、约束条件对受火RPC梁剪力传递机制和剪切破坏形态的影响，建立了基于结构体系的RPC梁斜截面承载火灾安全控制理论与抗火性能化设计方法。.研究成果为RPC结构火灾安全与耐火性能提升提供了科学依据，有利于RPC材料的推广应用，为土木工程绿色低碳可持续发展提供技术支撑。