Author Topic: Professor Greg Holland /Hurricanes  (Read 5535 times)

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Offline Mike

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« Last Edit: 04 February 2009, 07:15:31 AM by Mike »
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Offline Colin Maitland

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Re: Professor Greg Holland /Hurricanes
« Reply #1 on: 04 February 2009, 09:10:11 AM »
That is brilliant information, I agree that Australia has good building codes for cyclones in QLD,WA and NT. we used to build to what we called W33 - w41 in Brisbane. That is to withstain winds of 33M/s  & 41m/s. The cyclone rating used to be North of King Street Caboolture, but that was later moved way further north.

 Further north  there was W 50 and W60. The ratings now have new names.  But in all honesty there are many flaws in the code, much of the testing was under,what you could say lab conditions, not taking in the variables, but has he said, you have flying debris being a major player in carnage along with low lying areas for tidal surge, and many other things to contend with. I dont think we would have much left if a full CAT 5 hit us directly.

As you said cyclone will intensify as this climate change continues, but it is too late for some of the dwellings already built and where authorities have allowed them to be built.

I have the privilege to build some commercial halls in NSW, and the crews from QLD were shocked at the tie down system , or lack of it.

So how do we use the information you have brought to our attention to educate the public. The building code has to improve a great deal. Darwin incorporated a storm shelter system into the laundry with there designs after cyclone Tracy.

I had a mate who lived in Cairns and used to have  cyclone parties, what they were unaware of, is that the army flew in forty thousand body bags for one of the storms ( I think it was 1992, there was a cyclone 5 times bigger than TC Tracey) that fortunately did not make land fall. I noticed on the news, in Cardwell this week they showed the locals having a party at the pub. The owner said " it was a way they coped with the situation."

Thanks for sharing that information with us, I found it educational, interesting and important.





« Last Edit: 04 February 2009, 09:20:45 AM by coltan »

Offline Mike

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Re: Professor Greg Holland /Hurricanes
« Reply #2 on: 04 February 2009, 10:26:32 AM »
Just to add to that since your reply ignited something the professor said on building codes...in New Orleans and other cities where those big hurricanes hit some dwellings, there have massive concrete blocks in the roofs to 'stop the houses being uplifted' - when he viewed the destruction he asked one simple question:  Why are they not anchored to the ground?  They did not understand what he meant - he explained that imagine you're inside your home with this huge block of cement in the roof that is supposed to stop your house being lifted, then the hurricane hits and blows apart whatever supports it from underneath.  They got the picture!  No wonder some of those homes collapsed when the owners thought they'd be safe, if the hurricane did not kill you the cement block certainly would and even they were swept away by storm surge causing even more damage!

Even today typically here in Darwin our houses are all anchored some way either by U bolts anchoring the beans to the concrete pillars (elevated homes) and the ground level homes have Reo bars embedded into alternate columns of concrete into the core filled blocks.  even the corrugated iron we have has special clasps that seat under the screw heads that give some level of 'expansion' for the iron to move with the wind.  Whether in fact they will survive a constant battering of a CAT4-5 cyclone who knows, whatever their rated to nothing is 'set in concrete' until the event happens.

Oh..one photo he showed was the levy as Katrina struck.  The photo actually looked like a dam wall that was overflowing and in the foreground was a six foot tree.  The wall of water flowing from over the levy from the storm surge heading toward low lying suburbia was - unbelievable - 28 feet.  it was truly shocking to see this image and nothing was going to survive such a surge.

Darwin, Northern Territory.
StormscapesDarwin.com
Lightning Research 2010/14