# Decking Slab
A composite slab consists of profiled decking and concrete. The properties are adjusted to account for the reduced effective thickness of slab when decking is introduced. The modifiers for the 2D properties are calculated to allow for the modified geometry and the combined steel and concrete properties.
# Definition
Decking option
The decking can either be user defined, where the thickness and dimensions defining the profile must be specified, or selected from a catalogue of standard decking profiles.
The angle of the decking determines how the slab stiffness are determined. At 0° the properties calculated are for the slab in the slab span direction and the concrete in the trough is assumed to contribute to the stiffness, while at 90° the troughs are ignored.
Profile
The profile description is either a reference to the selected standard profile e.g. CAT RLSD Ribdeck AL (0.9) of a string of the form 'STD D 50 0.9 300 120 140 10 40' where the numeric values related to the depth, thickness and profile dimensions.
# Syntax
The description of hollow slab profile is
thick(unit) D angle CAT profile (t)
thick(unit) D angle STD d t b1 b2 b3 b4 b5
where
- thick – the overall thickness
- unit – the units defining the profile
- D – decking slab
- angle – angle of decking relative to x direction
- CAT or STD – catalogue or standard decking
- profile – the catalogue profile
- t – the decking thickness
- d – the depth of the decking profile
- b1, ... b5 – the dimensions which define the shape of the profile
