The steel connections listed in this article are designed in accordance with Australian Standard AS 4100:2020, Australian Steel Institute Connection Handbook 1, and Australian Steel Institute Design Guides 1-5.
Scope of the AS 4100 Module
Before going through the connection types, it is worth being clear about what the module covers under AS 4100.
AS 4100:2020 design in SkyCiv is for shear connections between I-sections, in metric units. Moment connections, splices and bracing connections are outside the current AS 4100 scope.
Universal Beam to Universal Column
Beam to column connections are among the most common connection types in steel design. The AS connections in SkyCiv are built around a supported beam framing into a supporting member, and the orientation can be set to a column flange support, a column web support, or a beam web support.
That third orientation means the same four connection types can also be used beam to beam, not only beam to column.
Only one connection to a node can be designed at a time. When dealing with back-to-back connections, it is advisable to take conservative assumptions on the load path.
Shear Connections
A shear connection is a simple connection. It is detailed to carry the beam end reaction and to rotate at the joint rather than to carry end moment, which is what separates it from a moment connection. In the AS module it is designed for shear alone, with no concurrent axial load.
For the AS design, the following shear connection types are available:
Each of the four is available beam to column flange, beam to column web, and beam to beam web.
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- Web Side Plate – Beam to Column Flange
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- Web Side Plate – Beam to Column Web
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- Flexible End Plate – Beam to Column Flange
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- Flexible End Plate – Beam to Column Web
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- Single Angle – Beam to Column Flange
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- Single Angle – Beam to Column Web
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- Double Angle – Beam to Column Flange
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- Double Angle – Beam to Column Web
The design of the above shear connections was based mainly on ASI Design Guides 3, 4 and 5. The reference formulas were taken from the AS 4100:2020 manual, while the rest of the calculations and criteria were taken from the ASI Connection Handbook 1.
Bolt Group Coefficient
For flexibility on the bolt arrangement and bolt spacing, SkyCiv adapted the ICOR method and inelastic analysis in determining the bolt group coefficient C, which is then used to calculate the bolt group shear capacity and bolt bearing capacity.
The Instantaneous Centre of Rotation Method (ICOR) uses iteration to locate the IC of the bolt group. SkyCiv uses its own solver for these iterations. The location of the IC is included in the calculations, but the iterations are not shown, to keep the report concise and readable.
The equation used to calculate the force per bolt using the inelastic analysis is based on AISC Eq. (7-1) on page 7-7 of the AISC 15th Edition Manual. The equation is shown below.
[math] R = R_{ult}\left(1-e^{-10\Delta}\right)^{0.55} [math]
This is a method borrowed for the bolt group solver, not a change of design code. The capacities themselves are still checked to AS 4100:2020.
Since the bolt group capacity adapted the AISC method, the provisions for determining the design bolt eccentricity of the bolt group also follow Table 10-9 of the AISC 15th Ed. This applies to SkyCiv’s AS Web Side Plate connection.
Eccentricity is handled differently for each type. For Single Angle connections, both the NSL and OSL legs are designed with load eccentricity. For Double Angle connections, only the NSL leg is designed with eccentricity, since the OSL leg is symmetrically balanced about the line of force. For Flexible End Plate connections there is no eccentricity either, as the load acts directly on the centre of the bolt group. Every bolt group without eccentricity takes the bolt coefficient C as the total number of bolts in the group.
Fixture Types
Each interface can be set as a bolted or a welded fixture, at the beam and at the support.
For the bolted case, see the documentation on bolts; for the welded case, see welds.
Detailing Limitations
Detailing limitations, the fit-up checks on the connections, are included in the AS connection design. Most of them are based on ASI Design Guides 3-5, while some follow an intuitive engineering approach.
These checks catch the connection that satisfies every strength calculation and still cannot be built or erected, which is a failure mode that strength checks alone will not find.
A pass or fail result for the detailing limitations appears on the Results tab, so it can be identified quickly. The calculation report also produces a table, shown below, so the item that needs to be modified is easy to pick out.
More Connection Types
Should you wish to see more connection types added under AS 4100, you may contact SkyCiv support.
Try it now
Pick a web side plate, flexible end plate, single angle or double angle, enter your beam, support and loads, and the module returns every check with its utilization ratio and the reference behind it, along with the detailing limitation table. It runs in the browser, with nothing to install, and you can do it without an account.
You can also reach it through the Free Steel Connection Design Calculator.
Sign-up to Free Account
A free account lets you save and reload your connection files, which the free tool does not. It also gives you access to the rest of SkyCiv’s structural software, including Structural 3D.
Connection Design Standalone
Want to use the connection design module only? Click the button below for the standalone pricing.
