Types of Steel Beam Connections and their Details

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There are various types of steel beam connections used in structures. Steel beam connections are categorized into two groups namely framed and seated connections. In the framed steel beam connections, the beam is connected to the supporting steel element through fittings whereas in case of seated connections, the beam is positioned on seat similar to the case where beam is placed on masonry walls. In this article, different types of steel beam connections are discussed.

Fig.1: Different Types of Steel Beam to Beam Connections

Fig.2: Steel Beam to Beam Connections

Types of Steel Beam Connections

Various types of beam connections are provided below:

• Bolted framed connections
• Bolted seated connections
• Welded framed connections
• Welded seat connections
• End plate connections
• Special connections
• Simple, rigid and semi-rigid connections

Bolted Framed Steel Beam Connections

In this type of connection, steel beams are linked to supporting elements whether it is steel girders or columns with web connection angle as seen in Figure-3.

Fig.3: Bolted Framed Steel Beam Connection

Commonly, the connection is designed based on the loads at the end of the beam. It is required to take strength, type and size of fasteners and strength of base materials into consideration while the connection is designed. The minimum length of connection angle should be at least half of the beam clear web depth. This measure is specified to ensure sufficient stiffness and stability. There are various standard sizes of bolted framed connections along with their capacity provided by codes. The purpose of such standardized connection is to increase the speed of the design. It is recommended to use minimum connection sufficient to withstand the applied load to make the design as economical as possible.

Bolted Seated Steel Beam Connection

There are two major types of bolted seated connections including unstiffened bolted seat connections and stiffened bolted seat connection as illustrated in Figure-4 and Figure-5.

Fig.4: Unstiffened Bolted Seat Connection

Fig.5: Stiffened Bolted Seat Connection

If the reactions at the end of the beam is large, then it is recommended to consider stiffened seat connections because it has adequate capacity to resist large forces whereas the capacity of unstiffened seat connection is restricted due to limited bending capacity of seat angle leg that stick out horizontally. The most outstanding advantage of seat connection is that the beam can be fabricated economically and seat would provide immediate support during erection. The function of the top angle used in seat connection is to prevent the beam to suffer from accidental rotations. It is worth mentioning that this type of connection does not need considerable shop detailing. Bolted connections are desired from environmental point of view because the structure can be dismantled and elements can be used in other projects. Added to that, bolted connections can be erected with great ease.

Welded Framed Steel Beam Connection

Like other two types of beam connections, various sizes of welded framed connections with their capacities are available and provided by codes. The weld of the connection is subjected to direct shear stress and stress caused by loads on the beam that affect weld pattern. So, these stresses are required to be considered. Clearly, part of the welding is carried out in the field which is challenging since it is difficult to achieve high quality weld due to movements of steel members caused by winds or other factors.

Welded Seat Steel Beam Connections

It is similar to bolt seat connection but welding is used for fastening rather than bolts. The loads on the beam affect the weld pattern eccentrically and generate stress. So, like welded framed connections, such stresses need to be considered. Types of welded seat connections include unstiffened seat and stiffened seat. The former is used in the case of small applied loads whereas the latter is suitable for case of large loads. It is advised to use bolts to connect beam bottom flange to the seat. These bolts can be removed or left at their position after the welding process is ended. Welded connection is not desired from environmental point of view and worker. This is because such connection is neither can be dismantled nor erected easily.

End Plate Steel Beam Connection

This type of connection is made possible through the use of welding art. The end plate is connected to the beam web through weld because its capacity and size is governed by shear capacity of the beam web adjoining the weld. The load applied on the connection at the end of the member does not have eccentricities. There are different types of end plate connections including flexible, semi-rigid, and rigid end plate connections. It should be known that, fabrications and cuttings should be conducted with utmost care to avoid errors. For example, cutting the beams to length must be as accurate as possible. Finally, end plate connections are not suitable for tall steel structures.

Special Steel Beam Connections

This type of connections is used for the case where the arrangements of the structural element are in such a way that standard connections cannot be used. For example, intersection angels might be different by a certain degree and when beam centers offset from column centers. Examples of special connections include bent-plate framed, single web plate, one sided framed, balanced web plate and Z type connection. The ability of connections to transfer moments to the columns is based on the degree of fixity of the connections. The higher the degree of fixity of the beam connection, the greater the ability to transfer moments to the columns. If the connection is designed to transfer moments, then it should be able to withstand shear forces from the beam and transfer moments to the columns. Read More: What are the Types of Structural Steel Framing Systems? Types of Floors Systems for Multi-Storey Steel Structure Construction Construction of Steel Frame Structure Foundations, Columns, Beams and Floors Properties of Structural Steel for Design and Construction of Steel Structures

References:

1. D G Brown, D C Iles, E Yandzio. Steel Building Design: Medium Rise Braced Frames: In accordance with Eurocodes and the UK National Annexes. The Steel Construction Institute. Berkshire, p. 72-75. 2009. (P365).
2. Frederick S. Merritt, Jonathan T. Ricketts. Building Design and Construction Handbook. 6th. ed. New York: McGraw-Hill, 2001.
3. Steel Framing. 2016. Cited on 28 October 2017.