[Bell Historians] Steelwork into masonary

[Bickerton, Roderic K (SELEX) (UK)]

I stand corrected thank you.
I wanted to address the long term problems, particularly in "wet"
towers, not the very short term, if not immediate failures at Kings Lynn
and Kelvedon, which I have not seen.

Rod Bickerton, 22/2/07

Sorry, Rod, this is untrue. Perhaps surprisingly, there is a close
similarity between concrete/stone/brickwork coefficients of expansion
and mild steel. It's why we can embed steel in concrete to make
reinforced-concrete. If the CoEs were very different, the steel would
either expand at a greater rate than the concrete as temperature
increased, causing it to buckle and crack the concrete, or the opposite,
which would pre-load the steel and make it fail early. The following
coefficients of expansion (taken from Kempe's Engineers Year Book) will
illustrate the point:-

mild steel: CoE 11.0 x 10-6
concrete: CoE 13.0 x 10-6
 
For comparison: copper 16.3 x 10-6 and aluminium 23.0 x 10-6
 
Concrete actually expands fractionally more than steel. 
 
(Did some work on this a few years ago and obtained CoEs for masonry and
brickwork, but can't turn them up now. They were similar to concrete -
which is effectively stonework anyway.)
 
Steel beams embedded in tower walls have no problem thermally. Actually,
the temperature inside a tower rises comparatively little compared to
the outside temperature, because it's in the shade. On this basis there
are potentially more thermal expansion problems within the walls
themselves, from what can be a substantial temperature difference
between the inside and out faces - but they seem to cope quite happily.
 
The problems at Kings Lynn and Kelvedon have, I believe, much more to do
with some quite different fundamentals of burying steelwork in masonry.
 
Chris Povey


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