Connection between beam and slab to achieve composite action

The connection between beam and slab is typically made using a number of stud connectors welded to the top flange of the steel beam.

Composite action is clearly dependent upon the steel and concrete acting in concert. The connection between the two is normally achieved by headed studs, typically 19mm in diameter, which are welded to the top flange of the beam and become bonded to the concrete.

Note that studs may be arranged in pairs or singly (for beams with narrow flanges) at regular intervals along the length of the beam.

Sufficient shear connectors and slab strength are necessary to ensure composite action.

The detailed design of the connection is clearly important. In particular it is necessary that:

• Sufficient shear connectors are provided to prevent slippage along the interface, and
• The concrete is able to accommodate the high localised stresses transmitted by these connectors.

These considerations will depend upon details such as the concrete strength, type of stud connector used and the slab thickness. They are matters of detail which would normally be the responsibility of an engineer and have no implications for the architect.

The Asymmetric Slimflor Beam (ASB), with a patterned top flange to achieve composite action without shear connectors, was developed by Corus.

A new beam type has recently been developed by Corus (formerly British Steel). This is the Asymmetric Slimflor Beam (ASB) which has a wider bottom flange to facilitate installation of slimflor slabs. The ASB also has a pattern rolled into the top flange to achieve composite action without the need for shear connectors, when used as part of the Corus Slimdek system, which includes a deep deck composite floor.