Using bolts as shear connectors of the steel–concrete composite beams enables prefabricated assembly and makes it possible to demountable and reuse the prefabricated components. However, studies on the fire resistance of prefabricated demountable composite beams (PDCBs) connected by bolts are limited. In this paper, four full-scale fire resistance tests were conducted to investigate the fire resistance of PDCBs connected by shear bolts with profiled sheet ribs parallel to the steel beam. Experimental observations, heating curves, deformation curves, and critical temperatures of specimens were obtained through fire-resistant tests. Test results show that the shear failure of bolted connectors occurred in the partially connected PDCBs instead of in the fully connected ones. Under the same load ratio, the fire resistance limit of PDCBs with fire protection was 4.4 times that of PDCBs without fire protection. The temperatures of the upper flanges of the steel beams in the PDCBs were overestimated by the existing codes. Moreover, numerical heat transfer analysis was carried out to investigate the effect of concrete slab thickness, concrete moisture content and steel beam upper flange dimensions on the temperature distribution of the steel beam upper flange. Finally, based on the results, relevant recommendations are made for the method of calculating the temperature of the steel beam upper flange in the PDCBs.

使用螺栓作为钢-混凝土组合梁的剪力连接件，可以实现预制装配，并使预制构件可拆卸和重复使用。然而，关于螺栓连接的预制可拆卸组合梁（PDCB）的耐火性研究有限。本文进行了四次全尺寸耐火试验，以研究采用与钢梁平行的压型板肋剪力螺栓连接的PDCB的耐火性能。通过耐火试验获得了试件的实验观察结果、加热曲线、变形曲线和临界温度。试验结果表明，螺栓连接器的剪切破坏发生在部分连接的PDCB中，而不是完全连接的PDCB中。在相同负载比下，带防火保护的PDCB的耐火极限是不带防火保护的PDCB的4.4倍。现有规范高估了 PDCB 中钢梁上翼缘的温度。此外，还进行了数值传热分析，研究了混凝土板厚度、混凝土含水率和钢梁上翼缘尺寸对钢梁上翼缘温度分布的影响。最后，根据研究结果，对PDCB钢梁上翼缘温度的计算方法提出了相关建议。