Re: Would welding the steel in re-enforced concrete add any value?

Jul 08, 2003 3 Replies


My builder is about to contruct the steel work which will soon be


> encased in concrete to make a 'raft'.
>
> Generally speaking, how are the grids of steel work normally 'joined'
> together? I understand that its tied with wire, but would there be any
> extra benifit in 'welding' it?
>
> My reason for asking is that I am learning to weld and would like the
> opportunity to practice.. If this would add any value to the build, I
> would be more than happy to spend a few hours welding the steelwork > together.
>
> As always, your thoughts would be apprecaited
>
> Jon

Hi Jon,



The bars are normally tied together with wire to allow them movement. I think welding would make them to rigid and could probably cause problems.



They're not. The point of steelwork in concrete is to compress the concrete by pre-tensioning the steelwork. For this you can treat each steel rod as a piece of flexible string - it doesn't matter what happens, so long as it supports this tension. So any attempt to weld the steel and make it "stiffer" as a structure is basically pointless.

Steel is often pre-welded into a grid, but that's just for convenience in handling. Similarly the use of wire ties to hold it in the right position.

I knew it was to add tensile strength but thought the compressing function was only in pre stressed concrete.

AJH

Yes, _pre-_tensioning was inaccurate wording on my part. That's just if they're tensioned whilst curing. The others only come into force if there's a tensile force or bending moment applied to the concrete.

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