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<DIV><EM><FONT face=Arial size=2>Burying steelwork in masonry is fundamentally
very dodgy.<BR>There is a lousy thermal miss match causing differential
expansion<BR>problems.</FONT></EM>
<P><EM><FONT face=Arial size=2>Rod Bickerton, 22/2/07</FONT></EM></P>
<P><EM></EM><FONT face=Arial size=2>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:-</FONT></P><FONT face=Arial
size=2></FONT></DIV>
<DIV><FONT face=Arial><FONT size=2>mild steel: CoE 11.0 x </FONT><SPAN
style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><FONT
size=2>10<SUP>-6</SUP><?xml:namespace prefix = o ns =
"urn:schemas-microsoft-com:office:office"
/><o:p></o:p></FONT></SPAN></FONT></DIV>
<DIV><FONT face=Arial><FONT size=2>concrete: CoE 13.0 x </FONT><SPAN
style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><FONT
size=2>10<SUP>-6</SUP><o:p></o:p></FONT></SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>For comparison: copper 16.3 x <SPAN
style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><FONT
size=2>10<SUP>-6</SUP><o:p></o:p></FONT></SPAN> and aluminium 23.0 x <SPAN
style="FONT-SIZE: 11pt; FONT-FAMILY: Arial"><FONT
size=2>10<SUP>-6</SUP><o:p></o:p></FONT></SPAN></FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Concrete actually expands fractionally more
than steel. </FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>(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.)</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>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.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>The problems at Kings Lynn and Kelvedon have,
I believe, much more to do with some quite different fundamentals of
burying steelwork in masonry.</FONT></DIV>
<DIV><FONT face=Arial size=2></FONT> </DIV>
<DIV><FONT face=Arial size=2>Chris Povey</FONT></DIV>
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