AS/NZS 3679.1:2016
Structural Steel — Hot-Rolled Bars and Sections
AS/NZS 3679.1:2016 specifies the requirements for hot-rolled structural steel bars and sections produced for use in structures designed to AS 4100 (steel structures) and AS 5100.6 (bridge steel and composite). It covers the chemical composition, mechanical properties (yield strength, tensile strength, elongation, impact toughness), dimensional tolerances, surface condition, and identification marking for structural steel grades 300, 350 and 400 (where the number indicates the specified minimum yield strength in MPa). The standard prescribes test methodology for tensile, bend and Charpy V-notch impact testing, and provides certification framework for steel producers. Section coverage includes hot-rolled I-beams (UB, UC), parallel-flange channels (PFC), tapered-flange channels (TFC), angles (equal and unequal), tees, hot-rolled solid square and rectangular hollow sections (where covered separately by AS/NZS 1163), flat bars and merchant bars. AS/NZS 3679.1 is the controlling reference for hot-rolled structural-steel section supply in Australia and New Zealand, paired with AS/NZS 3678 (plates) and AS/NZS 1163 (cold-formed and hot-rolled hollow sections). The 2016 edition replaced AS/NZS 3679.1-2010 and incorporated updated impact-toughness requirements, traceability provisions, and harmonisation with international steel grade designations.
AS/NZS 3679.1 is decision-controlling for two categories of TRSC engagement: existing-steel-structure capacity reassessment where the as-installed steel grade differs from current AS/NZS 3679.1 designations, and forensic assessment of brittle fracture or fatigue failure where the steel's chemical composition and impact toughness are decision-controlling. Three application points matter for existing-asset practice. First, the standard's grade designations (300, 350, 400) refer to specified minimum yield strength in MPa under current AS/NZS 3679.1, but Australian structural steel before approximately 1980 was designated by different naming conventions (Grade 250 to BS 4360, Grade 43 to earlier British practice, Grade A36 to ASTM under post-war US-supply influence). For continuing-life capacity assessment of pre-1980 steel structures, the as-installed steel grade must be re-mapped to the equivalent AS/NZS 3679.1 designation, with appropriate engineering judgement applied to the differing acceptance criteria. The Marina Mirage marine-deck connections and several Brisbane CBD heritage steel-frame buildings have been assessed under this re-mapping framework, with the resulting Form 15 capacity calculation using AS/NZS 3679.1 equivalent yield strength rather than the original-designation value. Second, AS/NZS 3679.1 impact toughness requirements (Charpy V-notch testing, typically at 0°C or 20°C ambient temperature) are decision-controlling for cold-environment and dynamic-loading applications. Pre-1980 structural steel often did not have impact-toughness specification, and brittle-fracture risk in cold or dynamically-loaded service is a real concern for continuing-life assessment. TRSC's protocol for steel structures in cold-storage applications, hospitality balcony and balustrade structures (which experience dynamic occupancy loading), and steel structures retrofitted from earlier eras includes Charpy V-notch testing of extracted samples where impact toughness is decision-controlling. The result is used in the AS 4100 capacity calculation with appropriate brittle-fracture factor, and the engineering basis is documented in the Form 15 file. Third, AS/NZS 3679.1 traceability provisions (mill-test certificates, identification marking, batch tracking) underpin the supply-side basis for new steel used in remediation. TRSC's remediation specifications for steel-frame strengthening, supplementary connections and replacement members reference AS/NZS 3679.1 grade designations and require mill-test certificates retained in the project file. For existing-steel structures without supply documentation (typical for pre-1990 buildings without complete construction records), the as-installed steel grade is established through extracted-sample chemical analysis (per AS 1391.1) and tensile testing (per AS 1391.1), with the resulting characteristic yield strength used in AS 4100 capacity calculation rather than assumed values. The Q1 Tower BMU rail post-Cyclone Albert assessment included this protocol — extracted-sample tensile testing on the bent and damaged rail sections established the as-installed steel grade and supported the AS 4100 capacity calculation for the make-safe specification.
TRSC Form 15 certifications for steel-element structural adequacy reference AS/NZS 3679.1:2016 as the supply-side standard for any new steel used in remediation, and as the comparison reference for re-mapping pre-1980 designation grades to current equivalents. The Form 15 file retains the AS/NZS 3679.1 grade designation, mill-test certificates for new supply, and where existing-steel grade is established by sampling, the AS 1391.1 chemical and tensile test results that support the characteristic yield strength used in capacity calculation. Where impact toughness is decision-controlling (cold-environment or dynamic-loading applications), the Form 15 documents the Charpy V-notch testing performed and the resulting brittle-fracture treatment in the AS 4100 calculation.