Establishing new brittle fracture provisions for the Australasian steel structures standards

Abstract

This paper develops a new method to select steel grades manufactured to Australian and New Zealand standards. The current materials selection procedure is currently given in the design standards AS 4100, NZS 3404.1 and AS/NZS 5100.6, which is based on test data on the notch toughness characteristics from a previous generation of steel products originally manufactured in Australia or New Zealand. The existing procedure is limited to temperatures down to −40 °C. Moreover, it does not consider the effect of welding, detailing, stress utilisation, seismic loading rates, defects and other important factors. This paper includes a critical review of other international material selection procedures, before preparing a new design method based on fracture mechanics. The method extends the temperature range down to −120 °C, which is much lower than considered in many other international standards. It also includes New Zealand specific requirements for seismic loading rates. In comparison with the new method, it is demonstrated that the current materials selection procedure is much more conservative for plate thickness up to 75 mm for non-seismic design. The paper presents selection tables that can be considered for the development of new brittle fracture provisions for future versions of the Australian and New Zealand steel structures design standards.