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Modelling Rebar and Defining Layers

Firstly, we must model the rebar mesh:

• A193 Mesh means that there is a total of 193mm^2 of mesh per metre length of slab in each direction.

• Instead of using a discrete series of bars, the mesh is considered as consisting of two smeared layers, reaching across the length of the slab and spanning in opposite directions.

• To conform with the properties of the 'true' mesh, the thickness of each layer is calculated such that they have an area of 193mm^2/m (i.e. each layer is 0.193mm thick).

Secondly, we must decide upon the number of concrete layers to use.  Layering is important as it allows the temperature distribution within the slab to be modelled accurately.  In general, a layer thickness of around 10mm is acceptable.

In this example, a standard depth of 13mm will be used in order to generate 10 concrete layers.  However, one layer will need to be slightly thinner, and one slightly thicker, in order to accommodate the rebar at the correct height.

With all this information in hand, it is possible to generate an idea of how the slab will be modelled: