Name of File :- Composite Floor 1
Traditional steel – concrete composite floors consist of rolled or built-up structural steel beams and cast in-situ concrete floors connected together using shear connectors in such a manner that they would act monolithically (Fig.1). The principal merit of steel-concrete composite construction lies in the utilization of the compressive strength of concrete slabs in conjunction with steel beams, in order to enhance the strength and stiffness of the steel girder.
More recently, composite floors using profiled sheet decking have become very popular in the West for high rise office buildings. Composite deck slabs are particularly competitive where the concrete floor has to be completed quickly and where medium level of fire protection to steel work is sufficient. However, composite slabs with profiled decking are unsuitable when there is heavy concentrated loading or dynamic loading in structures such as bridges. The alternative composite floor in such cases consists of reinforced or pre-stressed slab over steel beams connected together to act monolithically.
A typical composite floor system using profiled sheets is shown in Fig.2. There is presently no Indian standard covering the design of composite floor systems using profiled sheeting.
Designing a reinforced concrete slab or pre-stressed concrete slab in composite construction is not different from any conventional R.C. or pre-stressed structures; hence, this is not discussed any further here. In this chapter, concrete floors using profiled decks are treated in depth. The structural behavior of these floors is similar to a reinforced concrete slab, with the steel sheeting acting as the tension reinforcement. The main structural and other benefits of using composite floors with profiled steel decking are:
- Savings in steel weight are typically 30% to 50% over non-composite construction
- Greater stiffness of composite beams results in shallower depths for the same span.
Hence lower storey heights are adequate resulting in savings in cladding costs, reduction in wind loading and savings in foundation costs.
- Faster rate of construction.