Brittle fracture provisions in standards

Developing procedures and recommendations to select steel grades.

The materials selection procedure in design standards AS 4100, NZS 3404.1 and AS/NZS 5100.6 were based on outdated test data on the notch toughness characteristics from a previous generation of steel products manufactured in Australia or Aotearoa. This procedure was also limited to temperatures down to -40°C and didn’t account for critical factors like welding, detailing stress utilisation, seismic loading rates, defects and similar.

In contrast, advanced methodologies such as EN 1993-1-10 “Material toughness and through thickness properties” considered these factors using fracture mechanics for more accurate material selection. 

This approach has been adopted to develop updated selection requirements for AS/NZS steels in steel structures, in collaboration with the University of Wilhelmshaven and the University of Sydney. It is designed to withstand even cryogenic temperatures and includes New Zealand-specific requirements for seismic loading rates. It also offers recommendations for future updates to brittle fracture provisions in the steel structures design standards NZS 3404.1, AS/NZS 5100.6, and AS 4100.