Australian Building Code Formula for Wind

[ajk1]

Does anyone know the formula in the Australian Building Code for wind pressure on high rise building cladding?

 

[rapt]

ajk1,

You would find it in the Australian Wind Loading Code, AS1170.2.!

 

[rscassar]

AS1170.2 is available from saiglobal.com. It has been recently revised and I haven't checked the latest revision but the 2002 code was limited to buildings less than 200 metres in height. It does give equations for wind speeds as a function of elevation and terrain and wall pressure co-efficients and local pressure modifiers for cladding which is similar to the c&c pressure in ASCE.

 

[racookpe1978]

You have to remember everything flows backwards down under 'cause their upside down.... So Australian wind codes are just like US, UK or Canadian codes - except that the bottom of the building gets wind-analyzed, not the top. 8<)

 

[csd72]

And you have to design the foundations to stop it falling off the bottom of the earth!

ajk1, you may also want to get a copy of the commentary (which is a separate book) and the general loading code 1170.1? as this will contain some relevant information.

The wind loads are applied without factors but different return factors are used depending on the type of structure. Anything from 1 in 100 year return to 1 in 2000 years. Serviceability calculations are generally based on 1 in 20 year return. This information is contained in a chart in the building code of Australia or I believe it may be in As1170.1.

Components and cladding loads are obtained by factoring up the normal wind pressures in certain areas rather than using separate tables.

generally is is not that different from other major wind codes once you get to understand it.

 

[apsix]

Serviceability calculations were generally based on 1 in 20 year return, now amended to 1 in 25.

 

[ajk1]

Thanks everyone for this information on the Australian Code. The NBCC is based on 1 in 50 year return period. I think I will abandon my idea of using Australian Code. But I am surprised at how very high the wind loads on balustrades are. I would have thought that the air between the balustrade and the building would be compressed and apply a compressive wind force on the interior face of the balustrade to partially counter the compressive force on the exterior face of the balustrade, but this does not seem to be the case, unless I am missing something.

 

[rscassar]

The Australian wind code uses a higher return wind event but all Australian standards (steel, concrete, masonry, wood) are written in limit state format.

When you bang a 1.5 factor onto the 50yr wind in NBCC it will result in something similar to the Aussie standards.

Personally I am still using a 20yr return period for serviceability design (depite the post I started many years back which suggests a 25yr event should be used thread744-237727). A 20yr wind is still a category 1 cyclone for the southerners and category 3 cyclone for our friends in the tropics. Think of cyclone Winifred as being a serviceability wind event!!

A cyclone is a clockwise spinning hurricane.

 

[csd72]

Typical, not only do they drive on the wrong side but our friends in North America cant even spin their hurricanes the right way!

 

[ajk1]

to kikflip - thanks for the information