NZBridges 2012, Wellington, 29 - 30 October 2012 1 Proposed Joint Bridge Design Standard AS/NZS 5100.6 for Steel and Composite Construction Dr Stephen Hicks New Zealand Heavy Engineering Research Association (HERA), General Manager Structural Systems NZBridges 2012, Wellington, 29 - 30 October 2012 2 AS5100 revision • Standards Australia project with a duration of 3-years • Project kick-off November 2010 • Initial scope of project: • General reviewing and updating all Parts. • Updating Part 2 to be aligned to the earthquake code • Updating Part 4 to address new bearing and expansion joint materials. • Updating Part 5 in line with changes to AS 3600. • Following acceptance of proposals submitted to Standards Australia in February 2012, two new parts are being developed in parallel with the revision of existing AS5100 • Due to its size, AS5100 to be published in a lever arch file format for ease of future maintenance. • From NZ stakeholder consultation, including the Steel Bridge Development Group, confirmation from Standards New Zealand to revise Part 6 as a joint AS/NZS Standard NZBridges 2012, Wellington, 29 - 30 October 2012 3 Proposed suite of AS5100 parts Standard Committee responsible Description AS 5100.1 to .9 BD-090 Bridge Design AS 5100.1 BD-090-01 Scope and General Principles AS 5100.2 BD-090-02 Design Loads AS 5100.3 BD-090-03 Foundations (DPC ended 5 March 2012) AS 5100.4 BD-090-04 Bearings and Deck Joints AS 5100.5 BD-090-05 Concrete AS/NZS 5100.6 BD-090-06 Steel and Composite Construction AS 5100.7 BD-090-07 Rating AS 5100.8 BD-090-08 Rehabilitation AS 5100.9 BD-090-09 Timber Bridges NZBridges 2012, Wellington, 29 - 30 October 2012 4 AS/NZS 5100.6 • Kick-off meeting March 2011 • Draft for Public Comment document expected early 2013 • Committee Constitution: Stephen Hicks HERA (Chair) Peter Selby-Smith Cement Concrete & Aggregates Australia Anthony Ng BOSMA Arun Syam OneSteel Kumar Ponnampalan AUSTROADS Frank Rapattoni BOSMA Brian Uy UWS Peter Key ASI John Hilton Aurecongroup Gary Preddey Atlantic Civil Ken Wheeler Association of Consulting Engineers Australia Adrian La Manna Standards Australia NZBridges 2012, Wellington, 29 - 30 October 2012 5 Scope and Application • Sets out minimum requirements for design of the structural steelwork in bridges (wrought and cast iron structures may be checked in accordance with this Standard using appropriate capacity reduction factors) • Standard applies to the design of other steel components of bridges including steel piers, steel railings and sign structures. • Does not cover the following structures, members and materials: • Bridges with orthotropic plate decks. • Cold-formed members other than those complying with AS 1163. • Steel members for which the value of yield stress f y used in design exceeds 690 MPa (previously 450 MPa). • Steel elements, other than packers, less than 3 mm thick. NZBridges 2012, Wellington, 29 - 30 October 2012 6 Acceptance of steels • Test reports or test certificates that comply with the minimum requirements of the appropriate AS and AS/NZS Standards shall constitute sufficient evidence of compliance with these Standards • Test reports or test certificates may be provided by the manufacturer or an independent laboratory accredited by signatories to the International Laboratory Accreditation Corporation (Mutual Recognition Arrangement) (ILAC (MRA)) or the Asia Pacific Laboratory Accreditation Cooperation (APLAC) on behalf of the manufacturer. • In the event of a dispute as to the compliance of the steel with any of the AS and AS/NZS Standards, the reference testing shall be carried out by independent laboratories accredited by signatories to ILAC (MRA) or APLAC NZBridges 2012, Wellington, 29 - 30 October 2012 7 Steel types that comply with AS/NZS 5100.6 • Australia/New Zealand • AS/NZS 1163 Hollow sections 250 MPa < f y ≤ 450 MPa • AS/NZS 1594 Plate, strip, sheet floorplate 170 MPa < f y ≤ 380 MPa • AS/NZS 3678 Plate and floorplate 200 MPa < f y ≤ 450 MPa Includes weathering steel AS/NZS 3678-WR350 f y = 340 MPa for t ≤ 50mm • AS/NZS 3679.1 Flats and sections 280 MPa < f y ≤ 360 MPa • AS/NZS 3679.2 Welded sections 280 MPa < f y ≤ 340 MPa • AS 3597 Plate 500 MPa < f y ≤ 690 MPa • NZS 3404.1 currently permits the following overseas steels • EN 10025-2, EN 10025-2 and EN 10025-4 275 MPa < f y ≤ 560 MPa • JIS G 3106 and JIS G 3136 215 MPa < f y ≤ 460 MPa NZBridges 2012, Wellington, 29 - 30 October 2012 8 Ultimate Limit State conditions cover: • Provision of strength (STR) • Loss of Static equilibrium (EQU) • Failure from excessive deformation of ground (GEO) • Fatigue failure (FAT) Selection of Ultimate Limit State loads: • Design life = reference period R (normally taken as 50 years for buildings) • Return period T ~ - R / ln(1-p) ~ R / p where p = probability of exceedance during the reference period. • Load factor ≥ 1.0 Design for the Ultimate Limit State p f 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 | 4.75 4.27 3.72 3.09 2.32 1.28 p f = 7.2×10 -5 ≡ |=3.8 (typically used for ULS considerations). ULS SLS p f ≈ 10 -β NZBridges 2012, Wellington, 29 - 30 October 2012 9 Basis of Load and Strength capacity reduction factors • Normal distribution usually taken • Characteristic value • Mean value if variability small • Upper value (normally 95% fractile) if variability is not small • Design value based on probability of failure • Log-normal distribution usually taken (resistance doesn’t have negative values) • Characteristic (or nominal) value for resistance based on lower value (5% fractile) • Design value based on probability of failure. For large sample of data and a normal distribution • 5% fractile = 1.64 σ R • Design value = 0.8 x 3.8 σ R = 3.04 σ R (~ 0.1% probability of observing lower value) Loads Material and product properties u S S k S d -o S β σ S u R R d R k -o R β σ R o S and o R from ISO2394 o=1/¸ R ¸ S R k / R d =¸ R = 1/o NZBridges 2012, Wellington, 29 - 30 October 2012 10 Structural reliability analyses of beams in bending by UWS and HERA • Analyses on beam tests that have compact, not-compact and non-compact cross- sections show: • capacity factor of 0.90 given in AS 4100 and AS 5100.6 for beams in bending are on the conservative side for EN 10034 JIS G 3192 and JIS A 5526 manufacturing Standards. • Design practice that has been adopted in NZS 3404.1 for the last 35-years is supported (where no differentiation is made with respect to the capacity factors when steel complying with EN 10025, JIS G 3106 and JIS G 3136 is used). • Proposed to introduce overseas steels appendix in AS/NZS 5100.6 with minimum product conformity requirements equivalent to AS/NZS steels Parameter EN10034: 1993 JIS G 3192: 2005 JIS A 5526: 2005 AS 5100.6 AS/NZS 1365:1996 Depth (h) (mm) -2 -2 -h/50 Width (b) (mm) b≤110 110