Safety Factors for the Resistance of Steel Sections

The performance of the design equations given in the Australian Bridge and Steel Standards AS 5100.6 and AS 4100 have been evaluated when structural steel is used that conforms with the tolerances within the following overseas manufacturing standards: EN 10034, KS D 3502, JIS F 3192, JIS A 5526, ASTM A6/A6M-07 and AS/NZS 5100.6. From a consideration of the experimental results from full-scale bending tests, reliability analyses according to AS 5104: 2005/ISO 2394:1998 and EN 1990 were conducted. From these analyses, a capacity factor of between 0.93 and 0.95 was determined for beams that have compact, not-compact and non-compact cross-sections when a target reliability index of 3.04 was used, based on the standardised FORM (first order reliability method) sensitivity factor for resistance given in AS 5104: 2005/ISO 2394:1998. This finding demonstrates that the capacity factor of 0.90 given in AS 4100 and AS 5100.6 for beams in bending is on the conservative side for steel sections complying with overseas manufacturing standards, and supports the design practice that has been adopted in NZS 3404.1 for the last 35 years.