Joints in hollow section

Joints in hollow sections must account for the relative inaccessibility for bolting unless single sided bolting systems which permit the use of standard end plate or angle cleat connections are used.

Joints in hollow sections are fundamentally different from those used in open wall sections (Universal Beams, channels etc.), as the surfaces of tubes are much less convenient for fitting splice plates and bolts. Further guidance can be found in publications from Corus.

Hollow sections can be spliced using end plate (flange) or fishplate details.

The end plate connection is probably the cheapest, and also the most clumsy in appearance. It is suitable for compression, but less good for tension because the end plates are stressed through their thickness and bending is set up in the end plate. If the loads are large many bolts and thick plates will also be required. The heavy welding needed for such thick end plates brings more problems, as the heat input for the single sided weld can cause bowing of the plate.

A fishplate connection can be made between tubes with enough bolts to transfer the load through the connecting plates. In practical terms the joint must be considered as pinned, making it unsuitable for use in the middle of a member in compression. A cover plate of the same section as the main tubular components being joined can be used to mask the joint. This can be secured in place using countersunk bolts.

The welded splice joint is suitable for any combination of applied loads, but it provides no tolerance for erection and fabrication. Welds are however commonly used for connecting hollow sections during fabrication.