The Analysis And Study For The Cast-in-place Reinforced Concrete Hollow Flat-plate Floor System

The cast-in-place reinforced concrete hollow flat-plate floor is a new style of flat-plate floor. The weight of this floor is small and the span of this floor is large. Compared with the flat-slab floor, the flat-plate floor and the waffle floor, the cast-in-place reinforced concrete hollow flat-plate floor adapts the demands for the flat-plate floor system of this age. It has been used in some projects and has gained great social effects and economical profits.Compared with the normal flat-plate floor, the cast-in-place reinforced concrete hollow flat-plate floor has two special characteristics. To produce the hollow floor, the hollow columns are pre-buried in the floor. There are concealed wide-flat beams between the frame columns. On the basis of the characteristics of this new style of flat-plate floor, analyzing its basic mechanical behavior, researching on its sound calculating model and calculating method are of great importance to proceed the designing, ensure the safety of structure, spread the application of this new style of flat-plate floor.The two ways stiffness ratio of the reinforced concrete hollow slab is studied and the results show the reinforced concrete hollow slab is bent in two ways under the vertical loads providing the length of the two rims of the slab are near. The analysis for the concealed wide-flat beams demonstrates that it belongs to the column strip and it does not possess the function of the frame girder. A Material nonlinear finite element analysis for the cast-in-place reinforced concrete hollow slab that occurs from initial loading, cracking, yielding to failing is carried on. The cracking load, ultimate load, the displacement rules and the principal stress distribution rules of the hollow slab under the vertical loads are obtained. A Material nonlinear finite element analysis for the single span hollow flat-plate floor is also carried on. The function of the concealed wide-flat beams is definite by analyzing the principal stress distribution diagram. The calculating results verify the theoretical analysis and give some important conclusions which are great useful to improve the constructing of the new flat-plate floor. On the basis of the theoretical analysis and the finite element calculating, the conclusions show that the cast-in-place reinforced concrete hollow flat-plate floor should adopt the calculating method of the flat-plate floor. By using the calculating method of the flat-plate floor, the bend moments of the slab in different place are calculated. The moment distribution ratio between the column trip and the middle trip of the cast-in-place reinforced concrete hollow flat-plate floor calculated by the equivalent framemethod is demonstrated. The moment of the cast-in-place reinforced concrete hollow flat-plate floor calculated by the experience coefficient method is also demonstrated. Through the studies the practical conclusions have been obtained, which can be referred by engineers.