"Jon Weaver" wrote in message
om...
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.


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On 8 Jul 2003 16:27:48 -0700, (Jon Weaver)
wrote:

Generally speaking, how are the grids of steel work normally 'joined'
together?

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.

On Fri, 11 Jul 2003 00:38:01 +0100, Andy Dingley
wrote:


The point of steelwork in concrete is to compress the
concrete by pre-tensioning the steelwork.

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

AJH

On Sat, 12 Jul 2003 13:20:40 +0100, Andrew Heggie
wrote:

On Fri, 11 Jul 2003 00:38:01 +0100, Andy Dingley
wrote:

The point of steelwork in concrete is to compress the
concrete by pre-tensioning the steelwork.

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

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.