NCC overriding AS1170.2 for Western Australia (Region B & D) 1

[Euler07]

Hi All,

Please refer to pages 565 onwards from the NCC 2022 housing provisions (

https://ncc.abcb.gov.au/system/files/ncc/abcb-housing-provisions-2022-20230501b.pdf).

This is the WA state variation in the ABCB Housing Provisions, but a similar variation is in the NCC Volume 1.

The variation essentially overrides the wind loading calculations in AS1170.2 for wind region B and reduces the annual probability of exceedance for wind region D.

Is anyone able to answer any of the following questions or does anyone have any extra info they can share.
- Why has the NCC decided to override the wind code?
- Was the standards committee consulted and what is their view/comment? Does anyone have inside knowledge from the standards committee on this topic? Is this simply an early adoption of an AS1170.2 amendment?

There are many other questions that I could ask but hopefully someone has some information from the standards committee?

Thanks.

 

[human909]

From my very brief reading WA has chosen more stringent values for safety reasons. The standards committee may have been consulted but the NCC "sits above" AS1170, and references AS1170. I'd note the map used in NCC 2022 is out of date and doesn't include changes in 1170.2-2021. This may be an oversight or may have been due to reviewing and publishing timelines.

 

[PersonalProfile]

The following may be of interest as a start, though I am not from the committe:

1. A new 2021 edition of AS/NZS 1170.2 Structural design actions - Wind actions has been included for adoption in the 2022 edition of the National Construction Code (NCC).

The new edition of AS/NZS 1170.2 has many improvements, however it also includes a reduction in design wind speeds for wind Region D.

Mining activity in the Pilbara underpins the State’s economy and is a significant contributor to the national economy. If housing stock in this region was damaged, it would be difficult to accommodate the essential workforce and local communities.

The potential impact of a wind event would extend beyond just the local communities, and damage to new buildings associated with a cyclone in the Pilbara region would have a larger effect on the State of WA as a whole.

2. Dr Geoff Boughton AM, Senior Research Engineer, James Cook University Cyclone Testing Station was commissioned by Building and Energy to provide an expert report on the matter. This report has led to a Western Australian State variation to NCC 2022, which aims to retain similar design wind speeds for wind Region D as the 2011 edition of AS/NZS 1170.2 (referenced in NCC 2019).

Ex:

https://www.commerce.wa.gov.au/announcements/ncc-2022-state-variation-wind-region-d

Geoff has a PhD in Structural Engineering for work on wind loads on housing.

He is a member of a number of Australian Standards Committees including the committee for AS 1684, and the committees for the wind loadings standards, AS/NZS 1170.2 and AS 4055.

Ex:

https://www.jcu.edu.au/cyclone-testing-station/our-researchers/associate-professor-geoff-boughton

3. Geoff participates in the following forum, refer following example, that perhaps you can request the question.


AS4055 Serviceability Wind Pressure - Why is it so low?

https://eaxchange.engineersaustrali...-bce0-4091-897b-4fccbefb6472&tab=digestviewer

Regards.