Beam to column connections using Fin-Plates are probably the most widely used connection due to their relative ease of fabrication and erection. The main advantage lies with the fact that they are all Through-Bolted.
The following examples show typical connections graduating for the simplest and most straightforward to the more complex (and costly) alternatives.
Fig. 1 illustrates a typical connection using a Tee section welded to the end of the incoming member connecting to the Fin-Plate which is welded to the outside face of the supporting beam. The Tee may be a standard hot-rolled profile, or alternatively may be fabricated from plates. The incoming beam will therefore have a closed end.
Fig. 2 shows a variation of the former using a tongue plate which is welded to the inside of the profile extending to a depth not less than the depth of the beam. For large profiles the welding of the plate will not present a problem, but for smaller sections access to the weld may prove problematic, in which case the option shown in figure 3 may be more suitable.
Normally, this will result in a open ended beam, but often closure plate are welded to the beam end and tongue plate to seal the inside of the profile.
Fig. 3 shows a further variation using an extended tongue plate. In this case the plate is not welded inside the profile but is fitted into a slot cut into the top and bottom and welded from the outside. As with Fig. 3 - closure plates may be added.
Though these are listed as beam to beam connection options, they are more commonly found as Bracing Connections, which will be included in this series of articles.
As mentioned earlier, beam to beam fin plate connections can look a bit unsightly, but there is a method of 'hiding' the connection which is generally accepted by CIDECT, AISC and ISO illustrated below.
This works with the options illustrated in Figs. 2 and 3. The cover plates are defined as non-structural and are formed by cutting a profile in half wrapping around the joint. They are cut from a profile size matching that of the incoming beam.
They may be site welded after erection or alternatively, site bolted to tabs welded to the inside of the incoming beam profile. Either way, it's a lot of site work and should only be used at the discretion of the architect or engineer.
Connecting Open Sections
This is probably the most widely used configuration for connecting beams to hollow section columns. Fin-Plates lend themselves perfectly for connecting open section beams - they are easy to fabricate and equally trouble-free to erect on site.
When detailing these connections, it's usual practice to set out the connection from the top of the incoming beam - in line with Standard Fin-Plates, unlike when fixing a hollow section beam, where it's generally set out from the center of the incoming beam.
Below are illustrated some typical examples
Fig. 5 illustrates a typical fin-plate connection, with the plates welded to the face of the hollow section column and the incoming beam bolted through the web. Fig. 6 shows a much stronger variation, with the fin-plate passing though both faces of the column. This means cutting a slot in both faces of the column to allow the plate to be inserted - it's then shop welded from the outside.
This is a costly option and should only be considered at the discretion of the responsible engineer.