Experimental Study And Finite Element Analysis Of Cast-in-situ Reinforced Concrete Hollow Slab

Cast-in-situ reinforced concrete hollow slab with ceiling formwork is a new kind of floor structural system, in which ceiling plate and casting boxes are embedded orderly as inter forms. This paper focuses of the cast-in-situ concrete hollow slab that simply supported by four edges including its failure test subjected to vertical uniformly distributed load and nonlinear finite element analysis. The utmost load and the collapse mechanism are determined through the research. The suggestions of design and construction details are also given. The main contents are as follows:1. A 1.85m×1.85m cast-in-situ reinforced concrete hollow slab specimen is tested. The utmost load and the collapse mechanism are determined by observing the deformations, the cracks and the strain of the hollow slab subjected to vertical uniformly distributed load. At the bottom of the slab the yield lines which look like "#" are coincident with the ribs.2. By means of the separate modeling method, nonlinear finite element analysis is carried out by using ANSYS. The main works are analyses of the deformations, the cracks, the strain and stress etc. By comparison of the finite element analysis and test results, the results of finite element analysis about utmost load, yield lines, deformations are close to the test results. So the nonlinear finite element analysis verified the test conclusions. Meanwhile the comparison results also show that the nonlinear finite element analysis can be better carried out by the large finite element program in reinforced concrete specimen.3. The research results indicate that the deformations, the cracks, the collapse mechanism etc. of the hollow slab are essentially different from the solid two-way slab and multi-ribbed reinforced concrete slab. Compared with solid two-way slab, cast-in-situ reinforced concrete hollow slab is hollow and it's bending stiffness in tow directions are different. So cast-in-situ reinforced concrete hollow slab can be seen as reinforced concrete slab with ribs. Compared with multi-ribbed reinforced concrete slab, the thickness and space of cast-in-situ reinforced concrete hollow slab's ribs are smaller. There was no support relationship between ribs and slab. They can be seen as a whole having deformations together.4. Test and finite element analysis indicate that cast-in-situ reinforced concrete hollow slab with ceiling formwork has the characteristics of high-stiffness, high-capacity, bidirectional stress etc. It is suggested that in the process of the design and construction, the diameter of the reinforcement which are in the place of one third of midspan should be increased properly. Meanwhile the diameter of the reinforcement in the other areas should be properly reduced, and so does the reinforcement ratio of the hollow slab.