Shear connections are typically used to connect beams to other beams or columns. Such connections transfer shear, with minimum rotational restraint, as opposed to moment connections. This article is an overview of the AISC provisions for the design of shear connections. Our software ASDIP STEEL will be used to support the discussion.
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What are the components of a shear connection?
A typical shear connection is composed of three parts: support, connector, and beam. The support may be another beam or girder, a column flange, or a column web. The connector may be either bolted or welded to the support and to the beam. For example, a connector bolted to the support and welded to the beam forms a “bolted-welded” shear connection.
Typical connectors are single or double clip angles, single shear plates, and Tees. Shear connections may also be either stiffened or unstiffened seated connections. The image below shows schematically the different types of shear connections.
Double-angles are used for large end reactions, but may require additional considerations for erectability. It is common to find in practice double-angle connections bolted to the support, and shop welded to the beam. The image below shows the typical configuration of this type of shear connection.
How do you calculate the capacity of the connection?
The effect of the load eccentricity on the bolt group should be calculated per the Instantaneous Center of Rotation Method (ICR). Depending of the type of shear connection, a number of limit states must be checked accordingly. The design strength of the connection corresponds to the lowest strength of the applicable limit states, as briefly described below:
- Tension and shear bolt rupture – It checks the bolt strength under combined tension and shear.
- Bearing at bolt holes – It checks the bearing strength of the material upon which the bolt bears, either the support, connector, or beam.
- Shear yielding – It checks the shear strength over the gross area Ag of the connector or coped beam web.
- Shear rupture – It checks the shear strength over the effective area Anv of the connector or coped beam web along the full bolt line.
- Block shear – It assumes a block failure along a partial length of the bolt line, so it has a tension and a shear component. Applicable to connector and coped beam web.
- Flexural yielding – It verifies the bending capacity of a coped beam at the end of the tension flange cope.
- Flexural local buckling – Applicable to beams coped either at the top flange only, or at both flanges.
- Weld shear – It checks the shear strength of a welded connection, either at support or beam.
Are there any additional design checks?
In addition to the applicable limit states, the following values should be checked:
- Minimum weld size per AISC Table J2.4.
- Minimum connector thickness should match the weld strength.
- Maximum single-plate thickness should match the moment strength of the bolt group.
- Shear-bending interaction strength for single-plate connections.
- Minimum tee weld size or tee bolt diameter at the support, in order to provide rotational ductility.
- Maximum tee stem thickness bolted to beam, in order to provide rotational ductility.
As an example, the image below shows the limit states checks for a bolted-welded double-angle connection as designed by ASDIP STEEL.
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Best regards,
Javier Encinas, PE
ASDIP Structural Software