Steel concrete composite beams consists of a steel beam over which a reinforced concrete slab is cast with shear connectors. In conventional composite construction , concrete slabs are simply rested over steel beams and supported by them. These two components act independently under the action of loads , because there is no connection between the concrete slabs and steel beam.
When a shear connector is provided between concrete slab and steel beams the slip between them is eliminated and steel beam and concrete slab act as a composite beam. The behaviour of a composite beam is just like a Tee beam.
The basic concept of composite beam lies in the fact that the concrete is stronger in compression than steel (which is susceptible to buckling under compression) and steel is stronger in tension. By using the composite action of these two , the advantages of both materials are utilized to the fullest.
Advantages of composite beams:
• The concrete and steel is utilized effectively.
• More economical steel section is used in composite construction than conventional non-composite construction for the same span and loading.
• Depth and weight of steel beam required is reduced. So , the construction depth also reduces increasing the headroom of the building.
• Composite beams have higher stiffness , thus it has less deflection that steel beams.
• Composite beams can cover for large space without the need of any intermediate columns.
• Composite construction is faster because of using rolled steel and pre-fabricated components than cast-in-situ concrete.
• Encased steel beam have higher resistance to fire and corrosion.