The design of composite beams and slabs using decking can lead to a 30-40% saving in steel weight compared to non-composite construction due to the shallower beam sizes required. A wide range of steel beam and column sections are readily available. When compared to alternative methods of construction, composite decked slabs are significantly stronger and stiffer than timber an approximately half the weight of an equivalent precast or reinforced concrete solution.
In addition to its primary design function, composite metal decking can also contribute to other structural functions. Provided the fixings are designed to carry the necessary loads the decking can act as an effective lateral restraint to the beams during construction. Due to the continuity between the decking, reinforcement, concrete and primary structure the floor construction is robust. During construction the decking may be designed to act as a large floor diaphragm to redistribute wind loads. In addition, the composite slab can act as a diaphragm in the completed structure.
Speed of Construction
Decking is delivered to site on loads of up to 1000m' per load and can be fixed at a rate in excess of 400m' per day. The decking is loaded out in the area it is to be installed and fixed to the supporting beams with shot-fired pins using hand tools. The concrete topping requires minimal reinforcement and large areas of slab can be poured quickly in relation to other forms of construction. These advantages added to the minimal requirement for temporary propping (which can be eliminated entirely dependent on design) results in erection periods on average 50% quicker than equivalent in-situ concrete construction.
Due to the speed of erection, large areas of decking can be installed quickly. This provides a working platform capable of supporting typical construction loads and controlled storage of materials for following trades. The working platform created will also provide a safety net to floors below from objects falling from above.
The installation of composite decking removes the concreting process from the critical path of the project, therefore enabling large areas (only limited by practically) to be poured at once. Typically a concrete pump is used to the place the concrete; this is both fast and required no craneage. Depending on the floor finish / build up required. Slabs can be either floated level or 'power trowelled'.