Fire behaviour of continuous reinforced concrete slabs in a full-scale multi-storey steel-framed building

• Fire test on six continuous panels is conducted.
• Plateau phenomenon of deflections depends on the heated beams.
• Cracks have direct relationship with the number and location of the heated panels.
• The composite beams show excellent fire resistance behavior.

To further understand the fire behaviour of reinforced concrete floor slabs, a fire test was performed on six continuous panels (two by three) in a full-scale three-storey steel-framed building. In this paper, the test building, specially designed furnace and relevant experimental phenomena are briefly introduced. The furnace temperatures, temperature distributions, failure patterns as well as horizontal and vertical displacements of some structural components during the heat-up and cool-down phases were recorded and discussed in detail. The test data indicate that deformations of the heated panels have an important relationship with the boundary constraints around the heat panels. The plateau phenomenon of deflections at various measuring points mainly depends on the heated beams around the heated panels. The steel beams do not show partial buckling or failures due to constraints provided by other structural elements. Thus, taking advantage of the intrinsic design strength of the steel beams without applying fire retardant coatings can provide sufficient safety margins in similar engineering design scenarios. Moreover, the cracking characteristics at the upper surface of the heated panels have a direct relationship with the number and location of the heated panels in the floor. Several rational suggestions for the renovation of buildings subjected to fire can be quickly provided by utilising the cracking information.