Experimental Study Of Cellular Voided Two-Way Slab Made Of Reinforced Concrete In Place

The cellular voided two-way slab made of reinforced concrete in place is a new kind of slab which a lot of smaller boxed interior forms are embedded. It has many advantages, such as good mechanical behavior, equally flexural stiffness in two directions, high voided rate, having the flexibility to arrange the interior forms and convenient construction. Generally, the ratio of the distance s between ribs each other to the smaller space l1of the slab is less than 0.1, and the ratio of the thickness t of top solid slab to the thickness h for whole slab is more than 1/4. This kind of slabs has been used in more than ten engineering projects in P.R. China and has achieved a lot of social and economic benefits. In 2004, it was identified as an achievement in scientific research by the Department of Construction, Jiangsu Province.In this thesis, the development of voided slab made of reinforced concrete in place is reviewed, the present research and application states are also introduced. Meanwhile the calculating theory, the elastic finite element analysis and the 1/2 scaled specimen slab test of this kind of cellular voided two-way slab without bottom plate are made as major research in this thesis. The conclusion is that the internal forces and vertical displacements of the voided slab can be calculated as the elastic thin plate. In the end of the thesis, the engineering examples and some designing suggestions are given. The main contents are as follows.1. According to the theory of elastic thin plate with small flexivity and the theory of orthogonal anisotropy plate, the principle suppositions of the elastic theory of thin plate with small flexivity are discussed. These suppositions are modified when apply them to the cellular voided slab. The geometry equations, physics equations and differential equation of the cellular voided slab are deduced. If using the plate theory, the torsional stiffness of this slab must be reduced. By means of Weighted Residual method, an approximate solution is given. A suggestion is proposed that the interior forms should not be arranged at the area where the negative moment is large. The calculating method of the internal forces and vertical displacement for the cellular voided slab with four simple supported edges is presented.2. By means of the elastic finite element method, the internal forces and deformations of the cellular voided slab have been analyzed. The thesis comes to a conclusion that the cellular voided two-way slab to be calculated by means of cross coupling beam is incorrect. The thesis proves the correctness of calculating this slab on the base of the plate theory after the torsional stiffness is reduced. A method which combining a MATLAB program to solve the internal forces of solid element is presented. The correctness of both the solution which expressed by polynomial of this slab with four fixed edges and the internal forces solution from plate theory are proved.