Experimental Research On Fire-resistant Ability And Bearing Capacity Of Lightweight Aggregate Concrete Composite Floor

Application of profiled sheet-ceramsite concrete composite floors in buildings is the effective way to reduce weight of Multi-story steel famework. Compared with the commonly used concrete, ceramsite concrete can reduce floor weight about 25%, and then weight of the whole structure can be reduced about 10%- 20%, which will make good economic efficiency and the social efficiency.However, the poor fire-resistant ability is the main weakness of steel structures. The strength and elastic modulus decrease severely in high temperature. The steel will lost most of its strength and rigidity when the temperature is up to 400℃. Considering that the profiled sheet-ceramsite concrete composite floor will certainly have wide application in furture, the research work on the floors is quite necessary. Due to the reason mentioned above, the fire experimental and theoretical study of the bearing capacity of the profiled sheet-ceramsite concrete composite floors subjected to fire were conducted.The properties of ceramisite concrete are tested according to the requirements of the lightweight aggregate specification. Based on the influence of the material properties,water cement ratio and sand ratio, the LC25 concrete is made successfully, which has the density of 1760 kg/m3.Texts use YX76-305-915 type profiled sheet which iwas staple in china are used for research here object, five profiled sheet-ceramsite concrete composite floors were made and testedexperiment. The tests of behaviours of the four profiled steel sheet- ceramsite concrete composite floor under fire areis conducted, the thermal response and response of displacement are obtained. For study of the characteristics of the floor after fire, the experimental research on the post fire bearing capacity of the profiled steel sheet-ceramsite concrete composite floor subjected to fire are further carried out at indoor temperature , and the capacity of the floor not subjected to fire load are also tested . Based on the experimental results, effect of the fire on post-fire bearing capacity of the profiled steel sheet- ceramsite concrete composite floor is discussed, and the failure phenomenon and mechanism are analyzed. It is shown that increasing the thickness of floor can enhance the fire-resistant ability and the bearing capacity after fire. Welding studs will weaken the fire-resistant ability and the bearing capacity after fire. The failure form of the profiled steel sheet- ceramsite concrete composite floor after fire has great changement comparied with the floor not subjected to fire load , but the bearing capacity of it is still higher.At last, the finite element software of Marc is used for simulation, which shows that the simulated results concide with the experimental results to some degree although the complexity of the problems presented here obvious, which also show that the numerical method for analyzing the behaviour of the profiled steel sheet- ceramsite concrete composite floors subjected to fire is feasible.