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* Please note the above video was recorded while AS1170.2:2011, the previous version of the code, was in place. The ultimate wind speeds of each region have since been updated with the introduction of AS1170.2021, see below for more details.

Wind speed is an important factor in the planning and building of any new structure, including Fabric Shelters. It influences the design and engineering specifications of the proposed Structure. 

Every proposed DomeShelter Fabric Structure location will be assessed by your DomeShelter Consultant, to ensure it is given the appropriate design criteria and is properly engineered. Assessment takes into account Australian building standards, such as AS1170.2:2021, and involves three main factors: 

1. Wind Regions 

2. Terrain Category 

3. Importance Level 

Other criteria such as design working life and annual probability of exceedance may also be considered if applicable.

Wind Regions

‘Wind region’ refers to the classification of different regions of Australia, based on wind speeds and frequency of extreme weather events experienced in those areas. These regions have been determined according to the Australian Standards AS1170.2:2021 Structural Design Actions. 

You can see the map below for wind regions of Australia (criteria may differ in other countries). 

Australian Wind Code AS1170 map

The four regions are as follows: 

REGION A: “Normal”. Wind speeds of up to 162 km/h 

REGION B: “Intermediate”. Wind speeds of up to 205 km/h 

REGION C: “Cyclonic”. Wind speeds of up to 238 km/h 

REGION D: “Severe cyclonic”. Wind speeds of up to 288 km/h 

Terrain  Categories

Terrain categories are another important factor in building design and engineering. They relate to an area’s exposure to wind as a result of the surrounding terrain.  

TERRAIN CATEGORY 1: Exposed, isolated, flat, treeless and poorly grassed open terrain with few or no obstructions, measuring 10km radius or more. 

TERRAIN CATEGORY 2: Open terrain including grassland, with well-scattered obstructions of heights generally between 1.5-5m, such as trees and buildings, but no more than two obstructions per hectare. 

TERRAIN CATEOGORY 3: Terrain with numerous, closely-spaced obstructions, usually between 3 and 10 metres high. This terrain category usually relates to suburban, built-up or densely wooded areas. 

Importance Levels

“Importance Level” relates to the level of consequences to people or the public in the event of a building failure, as designated by the Building Codes of Australia. (BCA) There are four importance levels, as follows: 

IMPORTANCE LEVEL 1: Buildings with a low degree of hazard to human life and other property in the event of a building failure. Typically, level 1 should only be designated to isolated storage buildings. 

IMPORTANCE LEVEL 2: The default or ordinary level, for structures with medium consequence to human life and considerable economic consequences in the event of failure. 

IMPORTANCE LEVEL 3: High consequence for loss of human life or very great economic, social or environmental consequences in the event of failure.  

IMPORTANCE LEVEL 4: Exceptional circumstances, for buildings essential to post disaster recovery or those associated with hazardous facilities. A hospital, for example, would be considered importance level 4. 

For ease of reference, DomeShelter Australia assigns projects with one of two different importance level rankings, 1 being buildings with low level of consequence to human life and 2 being moderate to high consequence. Fabric Structures would not be used for an Importance Level 4 structure so this would not be applicable. 

Design Wind Speed Calculations 

Design Working Life 25 years / Max av. height 10m Terrain Category 2 for all calculations
Region A0 162 1 148
2 154
3 162
Region A1 to A5 162 1 148
2 154
3 162
Region B1 205 1 164
2 177
3 194
Region B2 205 1 163
2 176
3 192
Region C 238 1 192
2 207
3 255
Region D 288 1 226
2 246
3 271

* Region C – Cyclonic
* Region D – Severe Cyclonic
* Ultimate wind speeds as outlined in Australia New Zealand AS/NZS 1170.2:2021 Structural design actions – Wind actions.
* Design Wind Speed is calculated using specific Design Criteria (Terrain Category, Importance Level etc) related your site requirements. An example is: Wind Region Reg B2, Importance level 1, Terrain Category 2, Design working life of 25 years and a maximum average height of 10m = Design Wind Speed 163km/h

*All DomeShelter Structures are designed for Terrain Category 2 as standard.

How DomeShelter Australia Can Help

When you begin the consultation journey at DomeShelter Australia, location will be one of the first elements discussed. Based on your location, Wind Region, Terrain Category and Importance Level are all taken into account to calculate the Wind Speed Classification required to provide a fully engineered DomeShelter Structure in accordance with AS/NZS 1170.2:2021.

In some cases, site owners or local jurisdictions will also have specific requirements that will also have to be taken into consideration. For example, if a company wants to purchase a Shelter that will be moved often, from site to site, it would most likely be engineered for Region D wind speeds regardless, to ensure longevity and adaptability. 

It is extremely important to classify every Structure on a case-by-case basis and assess every location individually. If wind is not properly discussed or considered in the design process it could be hazardous and affect the longevity of your structure. Safety and Structural Integrity are keystones of our design philosophy here at DomeShelter Australia and we make it our duty to ensure every DomeShelter™ Structure is Engineered to Protect. 

Safety and integrity are paramount.

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