Importance Level and Steel Construction Category

[SteynvW]

I have a scenario where I have specified a Construction Category 3 according to AS5131-2016.
The contractor is obviously not happy.

The structure overall is an importance level 4 (Hospital) structure but in our project (internal fit-out) wall stiffeners
are added, and or some steel arrangement to stiffen up the walls in the fit-out.

Is there any justification that these members are not part of the main structure and are thus not Importance Level 4, and subsequently CC2 instead of 3?

 

[Agent666]

In my experience if a structure is importance level 1/2/3/4 then the fitout and any elements designed as parts are also expected to be 1/2/3/4 as per the main structure. There isn't really any mechanism available in 1170 to reclassify parts of buildings to another lower importance level.

Even if this was justifiable you'd have to get to importance level 2 before CC2 could really be justified based on the matrix in AS/NZS5131. So it's a big ask to go from 4 to 2 right?

The code basically says you 'may' use the matrix in the code to determine the construction category, not saying you absolutely have to. So as designer you can ultimately make the call on whether you use this?

The differences aren't really that different in practice, welder traceability, bit more material traceability, different welder qualification, possibly higher level of NDT depending on member category (keep in mind I'm commenting from NZ perspective, and some different Australian requirements for some things in AS/NZS5131 which I'm not really over). Refer to the appendix in standard for the differences.

Unsure if Australia has something similar to the SCNZ SFC scheme here, which is basically a pre-qualification of a fabricator to a maximum construction category. The biggest problem we have is dealing with fabricators that are not part of this scheme. They basically have no idea when it comes to 5131 and the compliance required, so we make it really hard for them to be used. Last time this occurred the fabricator decided it was just easier to go through the process of joining the scheme!

https://engineervsheep.com

 

[Retrograde]

Is there a Certifier involved in the project? If so, it should be their call.

 

[SteynvW]

Thanks for the replies.

Agent666
Yeah, the AS5131 Matrix Table does give the option for a CC2 in an importance level 3 structure if the service category is SC2, (Your NZ does not make a distinction there).
I feel this should be a pragmatic approach but do not want to go against industry norms.

Retrograde
Yeah, have talked to the client to speak to the certifier.