Air Pressure Loads - cyclonic winds
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Posted by: stevebydesign ® 03/28/2007, 16:13:54 Author Profile eMail author Edit

Hi Gang Calling on all those familiar with air pressure loads caused by cyclonic winds. Std Ref AS1107.2 and/or AS4055 I have a 20' ISO container, secured to the ground, in open flat terrain in cyclonic wind areas. std wind region speed is 70m/s What is the kPa on the walls What is the kPa on the roof My results differ quite a deal from the consulting engineers employed to quantify these values For those looking for some action The container tare wgt 2220kgs the container is 6.05m L x 2.44m W x 2.59 H What restraining masses do I need to prevent lift and prevent slide (on concrete u=0.4) Regards Steve S I dont want to build a 50tonne foundation so whats the min every one is too consevartive factors up too much

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Re: Air Pressure Loads - cyclonic winds
Re: Air Pressure Loads - cyclonic winds -- stevebydesign	Post Reply	Top of thread	Forum

Posted by: Bruiser ® 03/28/2007, 22:36:29 Author Profile eMail author Edit

'what's the min?' - 3 people were killed answering this question only weeks ago when a cyclone took out a mining camp in NW Australia. I probably don't know enough about your application to suggest you're taking shortcuts, but just in case, concrete is cheap compared to rebuilding and your consulting engineers should be able to support their results. Imagine telling a coroner 'I got my cyclone rating done online'...

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Posted by: stevebydesign ® 03/29/2007, 00:51:55 Author Profile eMail author Edit

Thats what we are trying to solve. The atco portable structures blew apart. Once a window is broken, int pressure plus updraft blows of the roof and then the walls tear apart We are going to use containers to do they same job. Foundations size isnt an issue, but consultants figures are rubbery. Side Wall Pressure... 6.5kPa Roof Pressure Up..... 7.2kPa based on a 90m/s wind speed ULS 1.1 Based on these pressure I could bolt the containers onto a boein instead of wings and away we go. Regards Steve S

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Posted by: Bruiser ® 03/29/2007, 01:53:21 Author Profile eMail author Edit

Agreed, a Boeing solution is the best, provided its timely. What if you put your tie downs over the top? I saw this done on site offices at Tom Price - 44 gallon drums full of concrete, then scaff bars up and over. Window protection? This sounds like it would prevent a lot of the problems. Refuge? If you buried sea containers you'd get rid of a lot of the forces and people would be safe from debris.

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Posted by: stevebydesign ® 03/29/2007, 05:59:35 Author Profile eMail author Edit

These are good replies But I actually need this data quanitified. 0.2M3X2.200kg/m3= 0.44 tonnes According to my sources they believe I need 50 tonnes how am going to stack.. 106 X 44 gallon drums I cant bury containers... Common fellas... Stop being so lateral and start be analytical Regards Steve S

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Posted by: Bruiser ® 03/29/2007, 11:41:32 Author Profile eMail author Edit

I see your problem - 106 drums and you may as well do tilt up. Going by your post,'...Atco buildings blew apart...', the problem is not with footings but with fixity - walls and roof. ie no matter how much you tie the base down, the top will rip apart. These dongas can be procured as 'flatpack' - that's how flimsy they are once erected. From my experience, the opposite effect (gravity as opposed to air pressure) takes over when they catch fire - they slowly implode. Even then the walls came off the roof, although that was more a 'mess' sized building than a quad donga. 'Darwin' construction methods have vertical rods within the walls tie the roof to the footing, and I think this will form part of your solution. Controlled vent panels (also secured) may augment this. With a twinkle in my eye, and having spent the odd 23n5 in a donga, get lateral mate! Don't get pressured into solving the problem on the terms you've been given (or dictated?). Stick with the cyclone basics: - limit flying objects - envisage structural failures - provide refuge It may not look good in the office, but the poor souls who'd otherwise be rolling around in their dongas will thank you. regards Bruiser

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Posted by: swearingen ® 03/29/2007, 09:41:27 Author Profile eMail author Edit

Following American codes, those pressures are very high for that cyclonic wind speed. I'm coming up with something about 1/3 of what you've given. It sounds like a very conservative design load to me.

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Posted by: stevebydesign ® 03/31/2007, 17:57:25 Author Profile eMail author Edit

Tanks Sweargin, I get about the same Wall 2.7kPa Roof 2.2kPa Nice to know I am not alone Regards Steve S

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