Abstract:
Slabs are surface structures which can derive their spatial configuration through continues three dimensional surfaces, and the loads are resisted by the surfaces themselves. These structures carry tension, compression and in-plane shear within the surface as membrane forces. Bending and transverse shear are carried either normal to or within the surface, depending on the loading and the surface orientation
Reinforced concrete slabs are used in floors, roofs in building, deck of bridges...ect. The floor system of a structure can take many forms such as in situ solid slabs, ribbed slabs or precast units. Slab may span in one direction or in two directions and they may be supported on monolithic concrete beams, steel beams, walls or directly by the structure’s columns.Normally they carry uniformly distributed loads. Slabs also tend to work as a diaphragm for lateral loads, it provide the overall structure stability by bracing columns.
Slabs are much more difficult to analyze because the surface geometry and the three dimensional material properties must taken into account.Slabs which are rectangular can be analyzed using the elastic analysis by idealization into strips or beams spanning one way or a grid with the strips spanning two ways, method of coefficients which is used for the two-way systems that supported on non-yielding beams and the direct design method which can be used for column supported slabs.
Slabs provide some of the most efficient structural systems in terms of material usage,cost, time, formwork and this leads to inherent economies.
