受火灾作用钢筋混凝土结构斜截面破坏机理与承载性能

With the fire simulation experiment system, the diagonal section bearing performance tests on the simply supported reinforced concrete beams subjected to direct or indirect loading respectively will be carried out in fire and after fire, and the shear resistance performance in shear bending region of reinforced concrete continuous beams after fire will be tested. With the experimental study on the beams, the diagonal section failure models and the bearing capacity degradation rules of the reinforced concrete simply supported beams subjected to direct or indirect loading respectively coupling with fire will be observed and analyzed, and the diagonal crack propagation law，failure modes and the residual bearing capacity of diagonal section of the reinforced concrete simply supported beams subjected to direct or indirect loading after fire action will also be observed and analyzed. And then,the diagonal crack propagation law，failure mechanism and the residual bearing capacity of reinforced concrete continuous beams after fire will be observed and analyzed , and the test results will also be compared with simply supported beams. Based on the test results , the influence of fire action on the diagonal section bearing mechanism of reinforced concrete structures will be systematically studied . Considering the influence of fire action, the analysis model and calculating theory for the diagonal section bearing capacity of reinforced concrete simply supported beams subjected to direct or indirect loading respectively will be explored , the calculation suggestions and design measures for diagonal section bearing capacity of reinforced concrete continuous beams after fire will be put forward.

本项目分别对直接加载和间接加载模式下的钢筋混凝土简支梁进行火灾作用下、火灾作用后的斜截面承载性能试验研究，对火灾作用后的钢筋混凝土连续梁进行剪弯区段斜截面承载性能试验研究。通过试验研究，观察和分析在火灾作用下直接、间接加载模式的钢筋混凝土简支梁斜截面破坏性态与承载力退化规律，以及受火灾高温作用后的钢筋混凝土简支梁在直接和间接加载模式下的斜截面裂缝发展规律、斜截面破坏性态以及剩余承载能力。观察和分析经历火灾高温作用后的钢筋混凝土连续梁剪弯区段的裂缝发展规律、斜截面破坏模式、承载机理以及剩余承载能力，并与简支梁试验结果进行分析比较。以此为基础，系统研究火灾高温作用对钢筋混凝土结构斜截面承载性能的影响机理，构建受火灾作用影响的直接、间接加载模式下钢筋混凝土简支梁的斜截面承载力模型和计算理论，提出考虑火灾作用后钢筋混凝土连续梁斜截面承载力的计算建议和设计措施。

该项目借助大型火灾模拟实验系统，对直接加载、间接加载的钢筋混凝土简支梁进行火灾作用下、火灾作用后的斜截面承载性能试验研究；进行了钢筋混凝土连续梁火灾作用后斜截面承载性能试验研究。通过试验，观察分析了在火灾作用下直接、间接加载模式的钢筋混凝土简支梁的斜截面破坏性态与承载力退化规律，以及受火灾高温作用后的钢筋混凝土简支梁在直接、间接加载模式下的斜截面裂缝发展规律、斜截面破坏性态以及剩余承载能力；观察分析了经历火灾高温作用后钢筋混凝土连续梁剪弯区段的裂缝发展规律、斜截面破坏模式、承载机理以及剩余承载能力，并与简支梁试验结果进行了分析比较。以试验研究为基础，直观展现和揭示了火灾高温作用对钢筋混凝土结构斜截面破坏模式和承载性能的影响机理。进而提出了考虑火灾作用的钢筋混凝土梁斜截面承载力的计算建议和设计措施，为结构抗火设计相关标准的建立提供了丰富的试验成果支撑。