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High strength reinforcement - AS 3600 vs AS 5100.5

bugbus

Structural
Aug 14, 2018
530
Here is a quick comparison of AS 3600 and AS 5100.5 regarding provision for high strength (> 500 MPa) reinforcement:

AS 3600 (including up to Amendment 2 as of 2021)
  • Scope allows for reinforcement up to 800 MPa, with a limit of 600 MPa to be assumed for ultimate limit states unless noted otherwise
  • No exemptions for shear and torsion strength (i.e., must assume 600 MPa as above)
  • Specific exemption to allow 800 MPa for column confinement calculations
  • No requirement for column fitments bars to be deformed

AS 5100.5 (including up to Amendment 2 as of 2024)
  • Scope allows for reinforcement up to 750 MPa, with a limit of 600 MPa to be assumed for ultimate limit states unless noted otherwise
  • Specific exemption to allow 750 MPa to be used for shear reinforcement (but funnily not mentioned for torsion, though this seems to be an oversight?)
  • Specific exemption also to allow 750 MPa for column confinement calculations
  • Column fitments are required to be deformed bars (Clause 10.7.6.2.1)

Does anyone know the reason for these differences? It seems AS 5100.5 is less conservative in some areas (e.g., allowing 750 MPa for shear strength) but more conservative in others (e.g., requiring column fitments to be deformed bars).

The reason this came up is that there are some higher strength reinforcement products coming onto the market in the last few years, including:
Sense 600:
Viribar 750:

Unfortunately, however, the Viribar 750 product is a plain bar and so is not allowed for use in columns by AS 5100.5. This would have been a nice thing to have on a recent project where we were forced to go back to D500N fitments on some pretty congested columns.
 
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I'm not up to date on the differences, but is AS 5100 a legal requirement to follow for your particular state, or is it in your contract that you must explicitly comply with every clause? Otherwise, deviation from standards for the purpose of improving design is completely allowed, if not encouraged, in the NCC.

I'm not sure what specific code covers bridges, or whether it's covered by state regulation, but the wording/structure might be similar to the NCC?
 
@Euler07, thanks for the reply. I have to admit I'm not aware of any legal requirements for AS 5100 to be followed. Usually it is stated in the contract.

Occasionally we will dip our toes into other design codes where AS 5100 is silent, but since the use of deformed fitments is so clearly stated it would maybe be hard to justify in this case.
 

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