How do they stand up?

[Rob_Webb]

Cranes I mean.... the big metal monsters not the birds. I've just been gazing out of the office window (again) watching these huge things moving rubbish from one side of the building site to the other. I mean (most) masts need shrouds and stays so how the donald duck do these things stay upright esp. in a hoolie?

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[bruce]

counter weight on other end of boom.

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[BrendanS]

Re: Theory of economy

They stand up to winds as they freewheel. but apart from that, I have this theory...

Go to the Oxo tower restaurant in London, South Bank. You can tell instanly how the UK economy is going. When things are bad, you can only see about 10 or less cranes. If the economy is going well, can see 30+ cranes?

<hr width=100% size=1>Me transmitte sursum, caledoni

 

[Nickel]

Re: Theory of economy

I've had the same theory for years - cranes mean growth.

Now in Pyortsmeef at the moment, all you can see are cranes down the saaf end of the island, and demolition plant up the noorf end - what does that tell me?

Tells me I'm spending too much time in Pyortsmeef, I reckon!

<hr width=100% size=1>Nickel

Being paranoid simply means - having all the facts.

 

[Stork_III]

The mast is bolted down to a large concrete base. The overturning moment due to windage and/or weight being lifted, is resisted either by Kenteledge (steel or usually concrete blocks on top of the concrete base, or using a larger base with piles into the substrata.

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[Shakey]

What I'd like to know is how they build the bloody things in the first place.

To build something that big you'd need a crane.

And it would have to be a bigger crane than the one you're building. So why don't they just use the bigger crane in the first place?

And how do you build the bigger crane, do you need an even bigger crane?

It makes my brain hurt.

<hr width=100% size=1>It could have been worse - it could have been me.

 

[wicked]

They do fall down sometimes

see: http://news.bbc.co.uk/1/hi/england/london/3257829.stm

Dave

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[Colin_S]

The biguns use a mobile crane to start the assembly and then they build theirselves by lifting up a piece of the tower into a mechanism that jacks up the top section and then slides the new part. There's a regularly repeated documentary on one of the Discovery type channels that gives loads of info.

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[Shakey]

Thanks for that, but I think you've spoilt the mystery of it now!

By the way do you know what dolphins and whales drink? They're mammals and mammals can't drink salt water, it's another one of them things that makes my brain hurt.

I only ask 'cos you've got the Discovery Channel so you might have seen summat about it.

<hr width=100% size=1>It could have been worse - it could have been me.

 

[AlexL]

Dunno, But I noticed Diving in corally places that theres loads of sponges on the reefs - so how come theres still water in the sea if its full of sponges ?/forums/images/icons/crazy.gif

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[Shakey]

What happens if you squeeze the sponges? Does the sea level rise?

<hr width=100% size=1>It could have been worse - it could have been me.

 

[Rob_Webb]

Thanks - now I can relax again!

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[PaulS]

Reminds me of a summer job I had one yr building metal grain silos on Pennsylvania farms. assembled the top ring...jacked it up...attached next ring...and so on until the silo was the height it was supposed to be. Built some pretty tall grain silos that way.

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[DJE]

Its called a cantilever. If you can get the wings of a 747 to work without shrouds and stays then a crane is easy. They do move an lot under load though. The cabs of tall tower cranes can be 30 to 40 metres above their highest fixed point; and they move several metres as they take up load. I am always amazed that the drivers don't get seasick.

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[Stork_III]

Re: Theory of economy

As an aside, do you know why its called the OXO tower?

Back in the late 19th C when it was built as part of a cold store for Vesty of Fray Bentos, Argentine Beef fame, the London Authority had at the time a ban on advertising along the Thames. So the designers got together with Crittal Windows and came up with three windows for the Tower with Mullions/transomes that formed the letters O X O.

So now you know.

Incidentally, when I designed the refurbishment of the reinforced concrete frame of the building in 1989, for conversion in to flats/commercial letting, you wouldn't believe the extent of the frost damage/corrosion to the concrete and reinforcing bars. 800 mm square columns with damage to 300 mm below surface with 32/40 dia bars waisted away by 60/70 %, and thats holding up 5 or 6 floors above. Thats what 40-50 years of permafrost will do to RC frames particularly with salted beef.

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[BrendanS]

Re: Theory of economy

Yep. already knew about the advertising thing.

Didn't know about corrosion damage though

<hr width=100% size=1>Me transmitte sursum, caledoni