Standards and design

Light gauge steel design standard

The primary design Standard for light gauge cold-formed steel structures in Australia is AS/NZS 4600:2018 ‘Cold-formed steel structures’. 

The objective of AS/NZS 4600 is to provide designers of cold-formed steel structures with specifications for cold-formed steel structural members used for load-carrying purposes in buildings and other structures. 

AS/NZS 4600 references applicable steel as being to AS/NZS 1163, AS 1397, AS/NZS 1594, AS/NZS 1595 and AS/NZS 3678 as appropriate. 

AS/NZS 4600 is in a limit state design format similar to AS 4100. The primary sections of the Standard are: 

  • Section 1: Scope and general 

  • Section 2: Elements 

  • Section 3: Members 

  • Section 4: Structural assemblies 

  • Section 5: Connections 

  • Section 6: Fatigue 

  • Section 7: Direct strength method 

  • Section 8: Testing 

  • Section 9: Fire design 

The design methodology in AS/NZS 4600 comprises two basic design approaches: 

  • The Effective Width Method (EWM) – Sections 2 and 3 

  • The Direct Strength Method (DSM) – Section 7 

The latest 2018 revision of AS/NZS 4600 has included the following significant improvements: 

  • A new Section 9 on design for fire 

  • An extension to Section 8 to include design based on testing

  • A new Appendix B for methods of analysis that allows design of complete structures, as done in AS 4100

  • Extensive revision, refinement and extension of the DSM approach. The EWM approach has been effectively ‘grand-fathered’ 

  • Appendix D brings together all the stability equations for local, distortional and global buckling together to simplify presentation

  • Improvement of design rules for connections, including new implementation for power actuated fasteners (PAFs). 

The 2018 revision of AS/NZS 4600 has provided a sound basis for analysis and design of cold-formed steel members and assemblies in areas such as mid-rise construction and modular construction, where significant performance demands are placed on the light gauge sections providing the primary structural support systems.