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Comparison of Deflection and Moment in One-way, Two-way, Flat Slab and Grid Slab of Various Sizes

Abdullah Al-Moneim, Mahmud Hasan


Slabs can be analyzed by considering them as beams (one-way slab), by using moment coefficient method (two-way slab) etc. Besides, exact analytical solutions are also available for some simple cases such as Navier’s method, Levy’s method, Timoshenko orthotropic plate theory etc. These methods are mainly used for analyzing slabs of simpler geometry and support. Slabs of various sizes, support and loading condition can be analyzed using Finite Element Methods (FEM) and a clear picture of deflection, stress and moment can be obtained. In this document, the main objectives are to analyze one-way and two-way slabs, flat slabs and grid slabs using finite element method and analytical methods and to determine deflections, moment and stresses in slabs due to loads applied normal to it. The results obtained from these two methods were then compared to validate the FEM solution. The FEM solution was found to be quite satisfactory. In one-way slabs, the moment in X direction decreases as slab size increases but the moment in Y direction gradually increases. In two-way slabs, the moment in X direction first increases and then decreases as increasing slab dimension. The moment in Y direction increases gradually just like one-way slabs. In flat plates and flat slabs, the displacement and stress are increased as slab size increases. Also, ordinary two-way slabs are not suitable for large spans where grid slabs are usually provided. The deflections and moments of grid slabs and two-way slabs were also compared in this document to investigate the suitability of grid slabs for large spans. Grid slabs may be used in case of large spans because its deflection is smaller than two-way slab.

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