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12/10/2021 11:54 am
I’d be interested in a show of hands on the following:
Say you’re designing a portal framed shed. (25m span, 50m long, 6m stud, 10deg pitch). 6m wide x 5m high roller slider door in each gable.
The windward roller door appears to be a dominant opening. Door area / Total open area (assuming 0.3% permeability) = 30/6.5> 4.6, so head to 1170.2 T5.1b and therefore Cpi = 0.85Cpe = 0.6
Or…. you could consider that the door is going to be closed in a limit state windstorm, therefore 2 walls somewhat permeable, and use Cpi = 0.2
It makes about a 20-25% difference to Cp_net, so not a worldchanger.
I do note that the standard discusses “…..roller doors shall be considered an opening unless they are capable of resisting applied wind pressure…..”
A quick comment back would be appreciated, along with any useful references.
eg.
A guide to AS/NZS1170.2 by Holmes and King
12/10/2021 3:59 pm
No reference sorry Andy – but I’d assume it was an opening. Not sure I’d trust that operating procedures to “close the door when its blowing” would be reliably adhered to.
16/03/2022 10:02 am
Andy,
We have been thru roller doors in detail with the amendment 5 of NZS1170.2 and 2021 version, the engineer needs to demonstrate the roller door is capable of resisting the wind load. Testing of roller doors are available for most doors I deal with, mostly BND, the testing is basically if the door is wider than 3-3.5m you need wind locks to be able to ensure they don’t fail (assuming 40m/s) and design the support structure for this catenary load (there is a good ASI paper on this).
Dragan Zdravkovic liked
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