Concrete beam

[Tim Lamb]

Is there any clever way of determining the construction/strength of an installed concrete beam?

A friend in Suffolk is having some conversion work done to a 1970's built house which will involve placing a significant additional load on the existing structure. The engineer has queried the load bearing capability of an existing 12"x12" beam.

Unfortunately there are no original plans lodged with the local authority. I don't know if building control would keep this sort of information after 30+ years.

Presumably the possibilities are cast in situ or bought in from a manufacturer. Perhaps the first move is to check for reinforcing steel? How? And then?

Structural steel can be measured and capabilities researched, are there similar standards for concrete?

regards

[Rob]

Leave it to your friend and his engineer and I am sure they will let you know in due course. It's up to your friend to follow professional advice, not just something you read on the Internet and passed on or it will be you that is held responsible when his house falls down!

[The Natural Philosopher]

I am sure there are..you need a structural engineer. Try Andrew Firebrace..they operate in East Anglia.

[dom]

Hi Tim -12" by 12" cross-section? That's a massive beam!

The Architects Pocket Book (Charlotte Baden-Powell, Elsevier Press) has standard tables of safe loads for prestressed concrete lintels (but nothing that large!) - though obviously those are for modern, factory produced units.

[Phil]

12" by 12" aint that big if it's cast in situ and not pre/post stressed. I've seen a 12" foundation crack while building a single brick wall on it - and that was supported underneath.

[Tim Lamb]

In message , Rob writes

I doubt anyone is daft enough to override professional advice because of something I say:-)

It is more a matter of reassurance that somewhere between the builder, the surveyor, the structural engineer and the architect a determination can be made.

It would be nice to think that such a beam would have an identifier linking it to the relevant standard.

As a regular guest, I have a personal interest:-)

regards

[Tim Lamb]

There is one already involved. The query came from a worried homeowner telephone conversation because the surveyor seemed uncertain as to whether the beam contained reinforcing or not.

regards

[Tim Lamb]

In message , Phil writes

The building got a design award so it does have some rather odd features. At 120 miles distant I can't accurately describe the construction.

regards both.

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[Dave Plowman (News)]

Reinforce it then. ;-)

[Tony Bryer]

If it's a 12"x12" RC beam it will presumably have been cast in-situ and the key determinant of its strength is the amount of reinforcement. ISTR that there are companies who can tell you this by x-ray analysis but it presumably doesn't come cheap.

[Tim Lamb]

Oh.

There was a concrete frame barn here until a rather impressive fire destroyed it. From memory, the legs were around 12"x8", built around

1960 by a company called Agrecon. (in the days before car rallying fell from favour a popular question asked the name of an 8 legged monster at the farm. A grecon! Ta-ra).

One thing I do recall was the smoothness of the concrete finish. Unlike the National Theatre, South Bank which looks like concrete scaffold boards.

regards

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[Roger]

The message from Tim Lamb contains these words:

As concrete is so weak in tension one would hope that any concrete beam would have some reinforcement in it even if, cast in situ, it hasn't been pre stressed. As to whether there is any iron within a magnet might give some indication.

If the building got a design award is it possible to track down the plans or the architect via that award.

[Tim Lamb]

In message , Roger writes

Yes. Or possibly a stud/nail finder.

I think the present owner stopped looking once she realised that Waveney District do not have records for the period.

Design award council eh? ISTR it was reported in the local press at the time but where would one start now?

regards

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[Dave H.]

"Tim Lamb" wrote

the local paper's archive? Most of 'em keep it in microfiche format, if you know / can guess when it won its award, you could go read 'em...

Dave H. (The engineer formerly known as Homeless)

[Andy Hall]

On Thu, 29 Jun 2006 08:52:37 +0100, [e-mail] wrote (in article ):

I guess that one might have to scout around to find that particular guide.....