火灾作用下整体结构中叠合板组合梁抗火性能的研究

As an important form of industrialization of construction industry, the laminated slab composite beam has been applied in many engineerings, but researchers pay little attention on fire resistance of that especially in overall structure. Existing research results showed that the fire behavior of composite beam is significantly different if composite beam has different concrete floor form. This applications will solve the explanation on fire behavior of laminated slab composite beam in overall structure and calculate the fire bearing capacity..Experimental study on the failure characteristics , fire behavior and influence of the interface of laminated slab composite beam coupling effect under load and fire will be conduct firstly, considering parameters affect such as end restraint of composite beam, the thickness of precast component, amount of shear studs. Second, considering the affect performance of end restraint and the interface, establish nonlinear finite element method to analysis the behavior of laminated slab composite beam coupling effect under load and fire, and conduct parametric analysis. Finally, based on the results of experimental and theoretical analysis, grasp the mechanical behavior of laminated slab composite beam in fire, establish the calculation method and practical formula on bearing capacity of laminated slab composite beam in fire.

作为建筑工业化的一种重要形式，新型叠合板组合梁已在众多工程中得到应用，而对其抗火性能的研究未被关注。已有研究结果表明：组合梁中混凝土板的形式不同，组合梁在火灾中的行为会明显不同。本申请拟从整体结构层面对叠合板组合梁火灾行为的机理进行解释，对火灾中的承载力进行计算。. 项目首先考虑结构中叠合板组合梁端部约束、预制部件厚度、栓钉间距的不同，进行叠合板组合梁使用荷载和火灾共同作用下的试验研究，获得叠合板组合梁火灾中的破坏特征、行为规律以及新旧混凝土结合界面对组合梁抗火性能的影响，探讨各参数对其力学行为影响的机理。其次考虑端部约束和结合界面的因素，建立叠合板组合梁在使用荷载和火灾高温耦合作用下非线性有限元分析的数值模型，并进行参数分析。最后基于试验和理论研究结果，掌握叠合板组合梁火灾行为的机理，建立火灾作用下叠合板组合梁承载力的计算方法和实用计算公式。

为研究火灾全过程叠合板组合梁的破坏形态、抗弯刚度以及剩余承载力，首先对叠合板组合梁进行恒载升温火灾试验，火灾试验时考虑后浇层厚度、预制底板搁置长度、栓钉间距的不同因素。试验结果表明：在受火时间和外部荷载均相同的条件下，后浇层厚度和栓钉间距是影响整体式叠合板组合梁抗火性能的重要参数，同时后浇层厚度和栓钉间距也是影响火灾后整体式叠合板组合梁抗弯刚度的主要因素；火灾后整体式叠合板组合梁的破坏形态与常温下基本相同，均发生受弯破坏，但经历火灾高温作用后，整体式叠合板组合梁出现裂缝的时间提前，其剩余承载力和抗弯刚度均有不同程度的降低，本次试验中火灾后整体式叠合板组合梁在荷载作用下的抗弯承载力和延性较常温下分别降低23.3%和55.4%；提出火灾下及火灾后整体式叠合板组合梁剩余承载力和抗弯刚度的计算方法，该方法具有良好的精度。. 研究结果补充了组合梁抗火设计的理论体系，为该组合梁体系抗火设计以及火灾后修复加固提供了重要参考价值。