Research On New Large-Span Bi-Direction Cellular Slab

On the basis of summarizing the existing large-span slab structure forms, the author developed the existing circular voided slab into a new large-span slab system, RC bi-direction cellular slab, which, specialized itself as bi-direction from a macro point of view, could not only reduce the tare weight of slab, but also expand slab span. With combined effort in theoretical analysis and FEM, the author studied engineering mechanism and distortion character, under vertical load, of RC bi-direction cellular slab, and put forward some ideas on construction design and practical formulations.Starting from virtual work principle, with the combination of FEM, the author led into elastic stiffness practical formulation of bi-direction cellular slab. After comparing the bi-direction elastic stiffness formulation with the approximately stiffness formulation, the author drew such a conclusion that if the hole-rib is comparatively big, the elastic stiffness of bi-direction cellular slab calculated by approximately formulation would be comparatively small, and therefore the elastic stiffness could calculated by the formulation illustrated in this paper.In light of the elastic thin plate theory, the author induced equilibrium differential equation of bi-direction cellular slab, which was proved correct through analysis and comparison to result of ANSYS to with theoretical calculation. Through the deflection and bending moment coefficient calculation of bi-direction cellular slab under various boundary conditions, the author brought forward the theory that the deflection of mid-span and bending moment coefficient calculation of mid-span and support of bi-direction cellular slab could be in accordance with solid plates', which could satisfy the precision of engineering.The author, applying the program of ANSYS, built a nonlinear model of RC bi-direction cellular slab, and, from the comparison of equivalent-span andequivalent-thickness solid plate, drew several important conclusions. Meanwhile he also pointed out that the stiffness of cellular slab would become weaker because of the holes of cross-section which make the tare weight 40% down comparing to solid plate, but if the weakness of tare weight was considered, the cellular slab still remained the excellent features of integration and stiffness, by which the cellular slab can be put into use of large-span.In the end, the author used FEM to analyze the short-period stiffness after RC cellular slab cracking, and presented recommended formulation in respect of short-period stiffness. Moreover, with regard to the features of bi-direction cellular slab, the author brought forward the equivalent cross-section stiffness model to calculate the ultimate load-carrying capacity of variable cross-section slab as well as the related reinforcement suggestions and conformation methods.