Beam calculations .. well sort of;!...

[Phil W Lee]

Java Jive considered Fri, 22 Mar 2013 15:38:40

+0000 the perfect time to write:

That would be my choice - less to lift each time (although you'd need either climbers or a tall cherry-picker, but then you'll probably need that anyway to attach the lifting strop (but maybe not as tall). The sections should be far more manageable individually, and less likely to get damaged (or even injure somebody).

There just ain't no way to get a vertical lift without lifting from the centre, and that seems impractical without lifting the whole thing from the top. And if the initial lift isn't vertical, something's gonna go pear-shaped. I wouldn't want to be anywhere close to a tonne of girders swaying about if it all goes the way of the pear when it tilts and a bolt or anchor-stud shears instead of being unscrewed. That's pingfukit on a grand scale.

A link to a photo would have helped, certainly. But it doesn't seem excessively complicated, unless there are access difficulties that haven't been mentioned.

[tony sayer]

This structure is all welded and cross braced high tensile steel and they are rather strong and fully galvanised etc.

The construction of them and the way there're constructed makes them very strong and rigid. The sections bolt together with flanges and quite sizeable bolts.

The reason for asking is that when a lot of these were built and there aren't that many around now mainly upgraded by larger mobile phone towers, they used to be man handled into place! Well the lowest part was. A steel scaffold pole or two used to be clamped to the first bit then a pulley and rope dragged the next bit up and that was bolted into place then the same for the third and the forth.

Course these days the HSI don't let them do that!. They used to make pole masts out of steel scaffold poles, 2 inches diameter, up to heights of 120 foot like this with just a man strapping the poles already erected and stayed into place. Very often this used to be atop a farmers barn for extra height!. I once took one down with a crane and man bucket from a barn up on Therfield heath, nice view:)..

Normally a mobile crane would be used but these are now very expensive and the people who want to take this down and move it elsewhere have been offered the use of a HIAB equipped lorry thats quite long and fitted with out riggers and the crane section can go to almost 15 metres height provided its within 2.5 metres overhang of the lorry. I believe it can lift some 3000 KG or more like that but until I see the full specification I wouldn't trust it!.

However as they can now pick this up at the midway point then its not likely to topple. I was just curious as to where the C of G would be on such a structure..