How do they do it?

[Bob Abell 2Participant @bobabell2]

Hello chaps

Driving along the motorway, looking at the light stanchions, I have often wondered over the years…….How do they set them so precisely?

It must be very difficult, and yet so simple to set them parallel to each other, somehow?

Don't forget too, that once the concrete sets…….That's yer lot!

Just curious………Bob

[Bob Abell 2Participant @bobabell2]

[Paul TParticipant @pault84577]

Hello Bob

The holding down bolts are positioned in the formwork before the concrete is poured, they are fixed for line and level using a laser theodolite, after the concrete has set the holding down bolts have an individual movement tolerance of +/- 20mm.

Easy when you know how.

Paul

[Bob Abell 2Participant @bobabell2]

Thank you Paul

I knew you would know the answer!

Can you imagine the load on those close pitched screws!…….In a strong wind!

Bob

[Colin BishopModerator @colinbishop34627]

Absolutely amazing. I always thought they started by planting a bulb….

Colin

[Paul TParticipant @pault84577]

Before the concrete goes in.

Bob the pull on an M24 bolt is approx 670N

Colin they plant a tube not a bulb

Paul

 

Edited By The Fat Controller on 03/07/2012 15:43:42

[Bob Abell 2Participant @bobabell2]

Thank you, Paul

I'm surprised the screw load is so low……..670 N is only about 175 lb

I'm still amazed how parallel they are aligned……In all directions too!

Bob

[Paul TParticipant @pault84577]

Hello Curly

The bolts are high tensile steel with very coarse threads and once cast in concrete the only thing they have to do is hold things in position.

However the pull load that I quoted is based upon a structural steel frame and not a single lighting pole so there would be extra calculations based upon wind load and potential horizontal impact damage.

Alignment using a laser theodolite is fairly easy as you just follow the red dot (setting up the machine though can be a nightmare) 

Paul

Edited By The Fat Controller on 03/07/2012 19:02:39

[Andy HustlerParticipant @andyhustler32076]

Paul i sit back in amazement , it's nice to now how every day things are made . My father was a marine engineer then after he left the navy he went into civil enginering doing everything from wraping pipes in bitumen to laying sewer discharge pipes in brazil . His father and uncle laid the floor ,in barry island pleasure p[ark , for the dodgems and he always said the island would sink into the waves before the flor fell apart as it was made out of boiler plate .Building model boats teaches people woodworking skills , Basic electronics and in a way some mathematics .

My next point ,of sorts !! , my brother belongs to a model enginering club in newport and they have a model boat pond which is not complete as theyt seem to concentrate on steam trains , they are really amazing models but not too hot on the marine side which is a great pity as there is only one place in newport to sail your boats and that tredegar house lake which can be busy with boaters and fishermen . Well thats my moan and groan over with !!!

Andy

[Paul TParticipant @pault84577]

Andy

Is your brothers club an informal arrangement or is it a company or charity?

If so they could apply for a lottery grant to complete the lake.

Paul

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