Classification of connections

Connections can be classified according to loading conditions.

Connections can be classified according to the types of loads they transmit, and the scale of those loads. A compressive load, for example, might be carried in several different ways, by direct compression between members, by welding between members, or by using bolted splice plates. In some cases, an equal tensile load in the same member could only be carried by welding.

A shear connection at the end of a simply-supported beam needs a different type of connection from tension and compression members, and if the same beam is not simply-supported but 'continuous' another type of connection capable of transmitting moments as well as shear forces is required.

The scale of the load and the size of the member can be important. For very large forces, even very thick plates may be inadequate and an alternative connection detail must be devised.

Connections can be classified according to the types of members connected.

Connections between steel members and other materials (e.g. concrete) will be different from steel to steel connections because the strengths of other common construction materials are much lower than for steel.

Connections between different types of steel section vary. In particular connection details for hollow sections (tubes) are quite different from those for open walled sections. This is largely because of the practical constraints on the location of welds and bolts

Connections can be classified according to whether they are exposed or hidden.

Exposed connections need to be designed from both aesthetic and practical points of view, and are usually developed by the architect and engineer working in close collaboration. In addition, externally exposed connections must be detailed to avoid corrosion by preventing the retention of water within the connection.

Connections which are not exposed are frequently designed by the engineer for economy, without consideration for appearance or size. However, care must still be taken over the size and position of hidden connections. For instance, a column splice may need to be detailed so that it remains within a ceiling void, otherwise the size of the column casing may be dictated by the bolts and splice plates, rather than the plain column section.

By using internal splice plates and countersunk bolts, the overall column dimensions can be minimised.