When working with steel structures, detailers use several types of connections to unify the construction which creates stability and support. There are two different categories of connections known as framed or seated connections. Framed connections use a supporting steel element with fittings to connect to the main beam. Seated connections position the beam onto a seat for a streamlined fit. In this article, we’re going to look at the different connections used in steel structures that are found in both categories.

Different connections used in steel structures

The type of connections used in steel structures varies depending on the scope of the project and the real-world limitations of the structure, such as positioning and the load weight. Below is a breakdown of the different types of steel beam connections and information about how they are implemented:

Bolted framed steel beam connections

These types of connections work by linking steel beams to various supports which could be steel girders or premade columns. They are most commonly used when the loads are located towards the end of the beam. Bolted framed steel beam connections are constructed with a few factors in mind, such as the strength and size of fasteners used and the strength of the base materials. When using these connections, it’s important to ensure that the minimum length of the connection angle is around half of the beam’s clear web depth to provide the right amount of stiffness and stability for the structure.

Bolted framed steel beam connections use standard sizes to coincide with their capacity, which is determined by predefined codes. This helps during the design process by making it easier to find the right size for a given connection. A good rule of thumb is to find the minimum requirement for the connection in terms of applied load to optimise the design.

Bolted seated steel beam connections

Bolted seated steel beam connections come in two types, unstiffened and stiffened connections. Stiffened connections are best suited for beams with large reactions at their tip to help resist large forces. Unstiffened connections have limited use as a result of their lower capacity for bending at the seat angle leg. Seated connections in general are a great option because they offer instant support upon erection and they can be made efficiently.

Seated connections are designed with a top angle, which stops any accidental rotations from occurring. It’s also easy to work with as it doesn’t require much detailing. Opting for a bolted connection is an excellent choice for sustainability as its components can be reused in other projects. They’re also relatively simple to erect, increasing project efficiency as a result.

Welded framed steel beam connections

Welded framed steel beam connections use a similar coding scheme to choose the right connection for specific capacities. The welds handle significant shear stress and load-bearing stress on the beam, so factoring in these stresses helps select the right connection. A good portion of the welding occurs on-site, so it’s not suitable for all projects.

Welded seat steel beam connections

These connections are very similar to welded framed steel beam connections but they use fasteners instead of bolts. They’re coded in a similar way too, so choosing the right type means considering different stresses. Opting for welded connections isn’t ideal because it makes it difficult to dismantle or reuse the components for other projects.

Special steel beam connections

Special steel beam connections are brought in when standard connections won’t work. There are a few different types, including single web plated, z-type or one-sided framed connections. They can shift momentum to the columns depending on the level of fixity found in the connections. If the fixity is high, then the transfer of momentum to the columns is greater. They can usually withstand shear forces from the beam and transfer momentum to the columns.