November 1 is the official beginning of the cyclone season, and we should be prepared for what is a reality of life in some of our biggest mining regions.
For the upcoming season, the Bureau of Meteorology (BOM) is predicting;
- ~40% chance of an above average number of tropical cyclones in waters off the northwest coast
(average number is five).
- Likelihood of around two coastal impacts.
- Significant risk of at least one severe tropical cyclone coastal impact.
You wouldn’t want to be outside! Or in a poorly designed building!
But it doesn’t need to turn out like on this photo below.
Through good engineering design, proper construction and using compliant building materials, structural damage can be minimised.
Here is a table showing the tropical cyclone intensity scale.
Tropical Cyclone Intensity Scale
Sadly, we see a lot of damage to houses and domestic structures from wind gusts around 100 kph.
In most of Australia, we design for at least 176 kph gusts at 10m in open terrain. We shouldn’t be seeing roof sheeting next door after a “strong wind” in Perth.
The difference in FORCE between a 100 kph wind gust and a 176 kph wind gust is HUGE! Actually, the factor is 3.1.
So when things blow over at 100 kph the force is only one-third of the design force required by our codes.
Poor or no design, poor construction, and inferior (non-compliant) building materials all contribute to this problem that insurance companies seem happy to pay out on.
In my opinion, structural damage should be avoided through proper design and construction in accordance with the National Construction Code (and that’s not that hard), and if it’s not, then the owner should be responsible for the effects of damage, and not the insurer!
Structures need to be properly designed for all expected loads and load combinations in accordance with our standards and regulations. For us as structural engineers, cyclones (and the remnant strong winds in non-cyclonic regions) are just another load case.
We perform structural audits on existing structures, particularly those on mining sites.
Ensure your structures are safe and compliant – especially those “temporary ones” that have been sitting there, unanchored, for 20 years – by having them assessed by a structural engineer.
Check out our services page for information about the structural services that we offer.
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