Analysis On Temperature Field And Flexural Bearing Capacity Of Prestressed Concrete Composited Slab Under High Temperature

Fire is a common disastrous question in the world. Fire resistance on structure is an important topic in structural engineering field. As slab is one of the important parts of structure, it is not only playing the role of separation, but also playing the role of bearing load. Reinforced concrete superimposed slab are widely used in the big tide of building industrialization. In order to optimize its performance a new type of prestressed concrete superimposed slab emerged for the optimization of these common superimposed slab. The prestressed concrete composite slab researched in this paper is a single span composite structure with prefabricated prestressed concrete soleplate and cast-in-place concrete, which with big stiffness, good overall performance and so on.The bearing capacity of floor under high temperature is insufficient will not only lead to the collapse of layer but also cause the entire structure collapsed. So when the fire is happened, superimposed slab should not only maintain completeness, but also stop fire from spreading to upper layer. The bearing capacity under high temperature is very important for the safety of the whole building. What’s more, different fire scenario has different fire develop features, which can be described using different temperature increasing curves. Therefore, it is necessary to study its temperature field and flexural bearing capacity under high temperature using rational approaches.In order to provide technical basis and reference for this new prestressed concrete composited slab, temperature field of cross section is studied and flexural bearing capacity under high temperature is carried out. The main contents are as follows:(1)Thermal performance and mechanical properties under high temperature of concrete, steel bar and prestressed steel wire are summarized and the various parameters were analyzed.(2) High temperature field theory of prestressed concrete composited slab is expounded systematically. Based on the hypothesis, heat equation of prestressed concrete composited slab is introduced.(3) Temperature field of cross section of prestressed concrete composited slab is analyzed using ABAQUS. The influence on temperature field of cross section of prestressed concrete composited plate under different temperature-time curves, different thickness, concrete over thickness, burning time in fire and surfaces exposed to fire are discussed, and ablation of slab is analyzed under different fire temperature conditions, which are the foundation for the next research on flexural bearing capacity under high temperature of prestressed concrete composited slab.(4) Flexural bearing capacity under high temperature of prestressed concrete composited slab is analyzed by finite element method and three steps model simplified calculation method. Stress-strain laws, deflection curve and fire endurance under high temperature of prestressed concrete composited slab are studied by finite element. The ultimate bending moment formula of prestressed concrete composited plate under high temperature is derived though a three steps model simplified calculation method. Then the equivalent fire floor live load is calculated, and the influence of different fire heating curve on composited slab is analyzed using equivalent fire floor live load.