Structural Steel Design Manual — AS 4100 Reference for Australian Engineers

A practical reference for structural steel design to AS 4100, covering member design, connection design, fabrication requirements and shop drawing documentation — with a downloadable reference manual and ASTCAD’s AS 4100-compliant structural drafting services.

Last reviewed: May 2026

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What is this manual?

This page provides a reference for engineers, structural designers, fabricators and CAD drafters working with structural steel in Australia. It covers key principles from AS 4100 — Steel Structures, Australia’s primary standard for the design of steel structural members and connections, and includes a downloadable reference manual. The page also explains how ASTCAD produces AS 4100-compliant structural steel shop drawings, fabrication drawings and connection details for Australian construction, mining and industrial projects.

AS 4100 is the standard referenced in the National Construction Code (NCC) and the Building Code of Australia (BCA) for all structural steelwork in Class 1–10 buildings and structures. Every fabrication drawing, shop drawing and connection design produced by ASTCAD’s structural team is checked against AS 4100 member capacity and connection requirements before issue.

Structural Steel Design Manual — reference PDF

The reference manual below covers structural steel design fundamentals including material properties, member design, connection design principles and fabrication requirements. For the current normative version of AS 4100, obtain the authorised copy from Standards Australia.

Structural Steel Design Manual — AS 4100 Reference

AS 4100 — Key design principles for structural steel in Australia

Material properties and steel grades

AS 4100 covers structural steel manufactured to the following Australian and international grades commonly used in Australian construction:

Grade 250 / 300 / 350 (AS/NZS 3678 — structural steel hot-rolled plates and floorplates, and AS/NZS 3679.1 — hot-rolled bars and sections) — the most common grades for beams, columns, angles and channels in Australian building and industrial structures
Grade C350L0 / C450L0 (AS/NZS 1163 — cold-formed structural steel hollow sections) — used for RHS, SHS and CHS in portal frames, purlins and secondary framing
Grade 8.8 / 4.6 bolts (AS 1110, AS 1111) — standard bolt grades for structural connections in Australia
Weld consumables to AS/NZS 1554.1 (structural steel welding) and AS/NZS 1554.5 (welding of high-strength steels)

Member design under AS 4100

AS 4100 uses a limit states design approach. The design action effects (bending moment, shear, axial force, torsion) must not exceed the design member capacities. Key member design checks include:

Section capacity (φNs, φMs, φVs) — cross-section yield and shear capacity based on gross or effective section properties
Member capacity in bending (φMbx) — reduced by lateral-torsional buckling using the slenderness reduction factor αs and moment modification factor αm
Member capacity in compression (φNcx, φNcy) — reduced by flexural buckling using the member slenderness reduction factor αc based on effective length Le
Combined actions — interaction checks for combined bending and axial compression/tension per AS 4100 Section 8
Web bearing and buckling — for beam webs at concentrated load and reaction points

Connection design under AS 4100

Connection design is covered in AS 4100 Section 9 and the Australian Steel Institute’s (ASI) Steel Designer’s Handbook. Common connection types in Australian structural steelwork:

Bolted connections — bearing-type (8.8/TB) and friction-type (8.8/TF) using snug-tightened or fully tensioned high-strength bolts. Design bolt capacity φVf (shear in bearing) and φNtf (tension) per AS 4100 Table 9.3.2
Welded connections — fillet welds (most common), butt welds (complete or incomplete penetration), and plug/slot welds. Design weld capacity based on weld size (s), length, and category (SP or GP) per AS/NZS 1554
Flexible end plate connections — standard shear connection for beams to columns and beams to beams, designed to the ASI simple connection tables
Moment end plate connections — fully restrained connections transmitting bending moment, shear and axial force between beams and columns
Base plates — pinned and fixed column bases, designed for compression bearing and hold-down bolt tension per AS 4100 and AS 3600 (concrete design for anchor bolts)

Fabrication and erection to AS 4100

Dimensional tolerances — fabrication tolerances for straightness, camber, web squareness and end preparation per AS 4100 Section 14 and AS/NZS 1554
Surface preparation and coating — blast cleaning to AS 1627 and paint application to AS/NZS 2312 for corrosion protection categories C2–C5 (Australian industrial and marine environments)
Weld inspection categories — SP (structural purpose) for primary members, GP (general purpose) for secondary members — all inspection requirements referenced to AS/NZS 1554.1
Erection tolerances — plumbness, column alignment, beam level and bearing tolerances per AS 4100 Section 15, typically ±3 mm for individual members and ±10 mm accumulated across a building grid

ASTCAD structural steel shop drawing services

ASTCAD produces structural steel shop drawings and fabrication documentation for Australian fabricators, structural engineers and builders across all project types. Our structural drafting deliverables include:

General arrangement (GA) drawings — overall structural layout, gridlines, levels, member mark schedules and section references
Shop drawings — individual member drawings showing all cuts, cope holes, bolt holes, weld preparation, plate thicknesses, grade callouts and surface treatment notes
Connection details — standard and non-standard connections including flexible end plates, moment end plates, base plates, splice plates and gusset plates, all designed and documented to AS 4100
Erection drawings — sequence and anchor bolt setting-out plans for site erection crews
As-built drawings — post-construction documentation for regulatory submissions and asset management
3D models in Tekla Structures, AutoCAD, Revit and SolidWorks for clash detection and BIM coordination

We serve fabricators and builders across Brisbane, Sydney, Melbourne, Perth and Gold Coast. Typical turnaround for a standard industrial portal frame set of shop drawings is 5–10 business days. Complex multi-storey or long-span projects are scoped individually.

Australian standards referenced in structural steel design

AS 4100-2020 — Steel structures (primary design standard)
AS/NZS 3678 — Structural steel: hot-rolled plates, floorplates and slabs
AS/NZS 3679.1 — Structural steel: hot-rolled bars and sections
AS/NZS 1163 — Cold-formed structural steel hollow sections
AS/NZS 1554.1 — Structural steel welding: welding of steel structures
AS/NZS 1554.5 — Structural steel welding: welding of high-strength steels
AS/NZS 1170.1 — Structural loading: dead and live loads
AS/NZS 1170.2 — Structural loading: wind actions
AS 1627 — Metal finishing: preparation and pretreatment of surfaces
AS 1100.101 — Technical drawing: general principles

Frequently asked questions

What is AS 4100 and is it mandatory in Australia?

AS 4100 — Steel Structures is the Australian Standard governing the design of steel structural members and connections. It is called up by the National Construction Code (NCC) and the Building Code of Australia for all structural steelwork in regulated buildings. Structural steel designs submitted for building approval in Australia must comply with AS 4100 (or demonstrate equivalent structural adequacy). The current edition is AS 4100-2020, which incorporated updates to connection design, serviceability and fatigue provisions from earlier editions.

What is the difference between AS 4100 and AISC (American) standards?

AS 4100 is Australia’s national standard and uses limit states design with Australian-specific capacity reduction factors (φ = 0.9 for members, φ = 0.8 for connections). The American AISC 360 uses a similar limit states approach (LRFD) but with different resistance factors, section classification boundaries, and connection design tables. AS 4100 also references Australian steel grades (Grade 250/300/350) rather than ASTM grades (A36, A992). For any Australian construction project, AS 4100 is the mandatory reference — not AISC. ASTCAD’s structural team works exclusively to AS 4100 and Australian material standards.

What does a structural steel shop drawing package include?

A complete AS 4100-compliant shop drawing package from ASTCAD includes: general arrangement drawings with member mark schedules, individual shop drawings for every fabricated member (beams, columns, braces, cleats and plates) showing full dimensioning, bolt hole patterns, weld preparation, material grade and surface treatment callouts, connection details for all non-standard and moment connections, an anchor bolt setting-out plan for the concreting subcontractor, and a materials list (BOM) cross-referenced to member marks. All drawings are issued in PDF for shop floor use and DWG/DXF for the fabricator’s CNC drilling and cutting machines.

Can you produce shop drawings for mining and industrial structures?

Yes. ASTCAD has extensive experience with structural steel documentation for Australian mining and industrial projects — including conveyor structures, plant platforms, pipe racks, mezzanines, and modular skid frames. These structures often involve Grade 350 or weathering steel (AS/NZS 3678-350L15 for impact requirements), heavy weld categories (SP, full penetration), and hot-dip galvanising to AS/NZS 4680. We document all of these requirements in the shop drawing package and coordinate with the structural engineer on connection design sign-off.

How do I get a quote for structural steel shop drawings?

Contact ASTCAD with your project brief — structural type (building frame, industrial structure, bridge, etc.), approximate number of members, software preference (Tekla, AutoCAD, Revit), and any existing structural engineer’s calculations or GA drawings. We will scope the deliverables and provide a fixed-price quote within 24 hours. For ongoing fabrication work, we also offer monthly retainer arrangements.

Related services and resources

Structural steel shop drawings — AS 4100-compliant fabrication documentation
Structural steel detailing — connection design and member detailing
Fabrication drawings — shop drawings for steel, aluminium and mixed-material structures
Structural design services — full structural engineering and drafting
AS 1657 reference — Australian standard for fixed platforms, walkways and ladders
Sheet metal design handbook — Australian design guidelines for sheet metal fabrication

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