AS/NZS 1163 SHS Dimensions for Cleat Connections: A Practical Guide for Structural Design

 In Australian steel construction, accuracy and compliance are non-negotiable. When designing reliable steel connections, especially cleat connections, understanding AS/NZS 1163 SHS dimensions is critical. Square Hollow Sections (SHS) manufactured under AS/NZS 1163 form the backbone of many structural systems, and their dimensions directly influence the performance of cleat connections.

This guide explains AS/NZS 1163 SHS dimensions for cleat connections, why they matter, and how engineers and builders can use them correctly for safe, compliant construction.

What Is AS/NZS 1163?

AS/NZS 1163 is the Australian and New Zealand Standard that specifies requirements for cold-formed structural steel hollow sections, including:

  • Square Hollow Sections (SHS)

  • Rectangular Hollow Sections (RHS)

  • Circular Hollow Sections (CHS)

The standard defines:

  • External dimensions

  • Wall thickness tolerances

  • Corner radii

  • Material grades (C250, C350, etc.)

  • Mechanical properties

For cleat connections, these parameters directly affect bolt bearing capacity, edge distances, and load transfer.

Why AS/NZS 1163 SHS Dimensions Matter for Cleat Connections

Cleat connections rely on the SHS wall to safely resist:

  • Bolt bearing forces

  • Tension and shear from connected members

  • Local plate bending and tear-out

If SHS dimensions are misunderstood or ignored, common issues include:

  • Premature bearing failure

  • Bolt pull-through

  • Plate deformation

  • Non-compliance with Australian Standards

Using correct AS/NZS 1163 SHS dimensions ensures cleat connections perform exactly as designed.

Key AS/NZS 1163 SHS Dimensions Relevant to Cleat Design

1. External SHS Size

Measured as width × width (e.g. 75×75, 100×100).

External size controls:

  • Available space for cleat plates

  • Bolt layout geometry

  • Minimum edge distances

2. Wall Thickness

Wall thickness is one of the most critical parameters for cleat connections.

Common AS/NZS 1163 SHS thicknesses:

  • 3.0 mm

  • 4.0 mm

  • 5.0 mm

  • 6.0 mm

  • 8.0 mm

Thicker walls provide:

  • Higher bearing capacity

  • Improved bolt performance

  • Reduced risk of tear-out


3. Corner Radius

AS/NZS 1163 specifies internal and external corner radii.

This affects:

  • How close cleats can sit to the SHS face

  • Fit-up accuracy

  • Effective bolt spacing

Cleats must be designed to avoid interference with curved corners.

4. Steel Grade (C250 vs C350)

Material grade influences:

  • Bearing strength

  • Net section capacity

  • Overall connection strength

Most structural SHS for cleat connections use C350, offering higher strength for bracing and framing.

These sizes are commonly paired with SHS cleats for beams, bracing, and timber-to-steel connections.

How SHS Dimensions Affect Cleat Connection Design

Bolt Bearing Capacity

Bearing capacity depends on:

  • SHS wall thickness

  • Bolt diameter

  • Steel grade

Thin SHS walls may govern the design rather than the cleat or bolt strength.

Edge Distance Requirements

AS 4100 requires minimum edge distances based on:

  • Bolt size

  • Material thickness

Incorrect SHS dimensions can reduce usable edge distance and weaken the joint.

Cleat Plate Thickness Selection

Cleat thickness must balance:

  • SHS wall strength

  • Bolt capacity

  • Applied loads

Oversized cleats on thin SHS walls do not improve capacity and may cause local failure.

This highlights why correct SHS dimension selection is critical for cleat connections.

Best Practices for Cleat Connections Using AS/NZS 1163 SHS

✔ Always verify SHS wall thickness from mill certificates

✔ Match cleat thickness to SHS capacity (not just bolt size)

✔ Allow for corner radii clearance

✔ Use galvanised cleats for durability

✔ Design to AS 4100 using AS/NZS 1163 properties

How SHS Cleats Are Designed Around AS/NZS 1163 Dimensions

At shscleats.com.au, cleats are engineered with:

  • Standard SHS external sizes

  • Typical AS/NZS 1163 wall thicknesses

  • Optimised bolt spacing

  • Compatibility with C350 SHS sections

This allows engineers and builders to:

  • Design faster

  • Reduce site modifications

  • Maintain compliance

  • Achieve predictable performance



AQs: AS/NZS 1163 SHS Dimensions for Cleat Connections

1. Can I use any SHS size for cleat connections?

Only SHS sections compliant with AS/NZS 1163 should be used. Non-standard sizes may not meet design assumptions.

2. Does thicker SHS always mean a stronger connection?

Generally yes, but the connection is governed by the weakest element — bolt, cleat, or SHS wall.

3. Are corner radii important in cleat design?

Yes. Ignoring corner radii can lead to poor fit-up and reduced effective bolt spacing.

4. Is C350 SHS better for cleat connections than C250?

C350 provides higher strength and is preferred for structural and bracing applications.

5. Should SHS cleats be galvanised?

Yes, especially for outdoor and coastal environments, to prevent corrosion at the connection.


Conclusion

Understanding AS/NZS 1163 SHS dimensions for cleat connections is essential for safe, efficient, and compliant structural design in Australia. SHS size, wall thickness, corner radii, and steel grade all directly influence cleat performance and load capacity.

By selecting cleats designed specifically around AS/NZS 1163 SHS sections, engineers and builders can ensure reliable connections, faster installation, and long-term structural durability.

For precision-engineered cleats compatible with Australian SHS standards,
 SHS Cleats deliver connections you can design with confidence.

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