预应力预制叠合楼板耐火性能参数分析

Parametric analysis of fire-resistant behavior of prestressed precast component composite slab

在合理选择混凝土和预应力筋材料的热工参数、高温力学参数的基础上,采用有限元分析软件ABAQUS建立底面受火的预应力预制叠合楼板的高温热力学模型,计算结果得到已有试验结果的验证。对影响预应力预制叠合楼板高温力学性能的各参数进行有限元分析,结果表明:荷载水平和耐火保护层厚度对叠合楼板耐火性能的影响显著,混凝土强度、预应力筋截面配筋率等参数对叠合楼板的耐火性能影响较小,可以忽略不计;耐火保护层厚度一定时,叠合楼板的耐火极限随荷载水平的提高而降低;荷载水平一定时,叠合楼板的耐火极限随耐火保护层厚度的增加呈非线性提高。在ISO-834标准火灾作用下,叠合楼板跨中挠度变化率速率大于L2/(9000d)可作为其达到耐火极限的判别标准。选取荷载水平、混凝土保护层厚度两个重要影响参数进行分析,提出了叠合楼板的耐火极限取值建议,为预应力预制叠合楼板的抗火设计提供技术参考。

Finite element models of prestressed precast component composite slab heated by ISO 834 standard heating curve were developed, and the suitable thermal and thermodynamic parameters were selected for the analysis. The accuracy of FEA model was proved by the comparison with the results of fire experiments. Different influencing factors were taken into account for the parametric studies to describe the fire performance. The numerical results showed that the effects of the fire protection coating thickness and the loading level on the fire-resistant of composite slab are significant. The influence of the concrete strength and the reinforcement ratio has little effect on the fire resistance of the composite slab and can be neglected. The results also showed that the fire-resistance of the composite slab will be reduced with the loading level increases for a certain fire protection coating thickness and it will nonlinearly increase with the fire protection coating thickness increase for a certain loading level. In the ISO-834 fire the mid-span deflection rate L^2/（9000d） can be used as the criterion to determine the fire resistance of the composite slab. Based on the FEA results, the recommended values of fire resistance were proposed, which can provide fire resistance design reference for composite slab.