To investigate the fire resistance of composite beams with restrained superposed slabs, three specimens were tested under uniformly distributed loads in a furnace. The effects of the thickness of the postcast top layer in superposed slabs and the spacing of shear studs on the structural behaviours of composite beams under fire were further examined. During the tests, the temperature distributions of the superposed slabs and steel beams as well as the displacements at their key positions were recorded and analysed. It was found that the temperature of the concrete superposed slabs decreased long their heights from the bottom. The most drastic change of the temperature along the slab cross section was found in the region with a distance of 40 mm to the slab bottom. The concrete superposed slabs could impose restraints to the steel beams due to their incompatible deformations. Cracks were developed on the top surfaces of the specimens and the superposing interfaces between the precast slabs and postcast top layers were not broken. Through the comparisons of different specimens, the spacing of shear studs could have a significant effect on the fire resistance of composite beams, especially for their deformation recovery capacities. In contrast, the effect of the thickness of the postcast top layers was negligible. ABAQUS was employed to simulate the temperature fields and deformation behaviours of composite beam specimens based on a sequenced thermomechanical coupling analysis. The numerical results agreed well with the experiment data, which validated the developed numerical model.

中文翻译：

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带约束叠合板的组合梁的耐火性

为了研究具有约束叠加板的复合梁的耐火性，在炉中均匀分布的载荷下测试了三个样本。进一步研究了叠合板中后浇顶层厚度和抗剪栓钉间距对组合梁受火的结构性能的影响。在测试过程中，记录并分析了叠置的平板和钢梁的温度分布及其关键位置的位移。已经发现，混凝土叠置板的温度从底部开始高度下降。在距平板底部40 mm的区域中，沿平板横截面的温度变化最为剧烈。叠置的混凝土板可能会由于其不兼容的变形而对钢梁施加约束。试样的顶面上出现了裂纹，并且预制板和后期铸造顶层之间的重叠界面没有破裂。通过比较不同的试件，剪力钉的间距可能对组合梁的耐火性产生重要影响，尤其是其变形恢复能力。相反，后浇铸顶层的厚度的影响可忽略不计。基于顺序热力耦合分析，ABAQUS被用来模拟复合梁试件的温度场和变形行为。数值结果与实验数据吻合良好，验证了所建立的数值模型的正确性。试样的顶面上出现了裂纹，并且预制板和后期铸造顶层之间的重叠界面没有破裂。通过比较不同的试件，剪力钉的间距可能对组合梁的耐火性产生重要影响，尤其是其变形恢复能力。相反，后浇铸顶层的厚度的影响可忽略不计。基于顺序热力耦合分析，ABAQUS被用来模拟复合梁试件的温度场和变形行为。数值结果与实验数据吻合良好，验证了所建立的数值模型的正确性。试样的顶面上出现了裂纹，并且预制板和后期铸造顶层之间的重叠界面没有破裂。通过比较不同的试件，剪力钉的间距可能对组合梁的耐火性产生重要影响，尤其是其变形恢复能力。相反，后浇铸顶层的厚度的影响可忽略不计。基于顺序热力耦合分析，ABAQUS被用来模拟复合梁试件的温度场和变形行为。数值结果与实验数据吻合良好，验证了所建立的数值模型的正确性。