Abstract This paper presents the results of tests to investigate fire performance of two-way restrained precast concrete (PC) composite slabs under the standard ISO 834 condition. The fire tests include three specimens with different load levels and boundary conditions – with or without restraints around the edges. Tensile membrane action was observed to a moderate extent in all specimens tested, including the reference test at ambient temperature. No debonding was observed at the interface between the bottom precast slab and the top cast-in-situ composite layer for the restrained PC composite slabs, but cracks formed at the interface in the un-restrained PC composite slab. These results demonstrate much increased fire resistance due to restraint effects (195 min vs. 130 min) if the same load (195 kN) is applied, but similar fire resistance if based on load ratio (131 min and 130 min at the same load ratio of 0.42). A number of existing theoretical methods developed for calculating tensile membrane action effects of two-way concrete slabs, as well as the conventional yield line theory, are employed to calculate the load carrying capacities. They indicate that for the type of slabs investigated in this paper, the improvement due to tensile membrane action is moderate.

中文翻译：

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双向约束与无约束预制混凝土组合板耐火性能对比试验研究

摘要 本文介绍了在标准 ISO 834 条件下研究双向约束预制混凝土 (PC) 复合板防火性能的试验结果。防火测试包括三个具有不同载荷水平和边界条件的试样——边缘有或没有约束。在所有测试的样本中都观察到中等程度的拉伸膜作用，包括环境温度下的参考测试。受约束的PC复合板在底部预制板和顶部现浇复合层之间的界面没有观察到脱粘，但在未受约束的PC复合板的界面处形成了裂纹。这些结果表明，如果施加相同的载荷 (195 kN)，由于约束效果（195 分钟对 130 分钟），耐火性大大提高，但如果基于负载比（131 分钟和 130 分钟，相同的负载比为 0.42），则具有相似的耐火性。一些现有的用于计算双向混凝土板拉伸膜作用效应的理论方法以及传统的屈服线理论被用来计算承载能力。他们表明，对于本文研究的板坯类型，由于拉伸膜作用的改进是中等的。