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Re: Steel Building in Alaska

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To Syed Faiz Ahmed,

	It is essentially a fracture mechanics problem with material toughness,
flaw size, magnitude of tensile stresses, and strain rate being the
principal variables.

	As I said earlier, buildings are not usually troubled by brittle
fracture at low temperature so David Chan probably doesn't have to deal
with it.  Other structures such as bridges, bollards, industrial and
transportation equipment exposed to the weather can be seriously
affected.

	Steel undergoes a transition from high toughness (as measured by tests
like the Charpy test) to extremely low toughness over a very narrow
temperature range.  The challenge steel makers face is the desirability
of lowering that transition range (and, of course, this costs money). 
The use of older steel in restored or rehabilitated structures can also
pose problems.  Some of the "Liberty" ships built in the U.S.A. during
World War Two actually did split in half as shown an the cover of your
magazine and I understand that even the Titanic may have been affected.

	The text book I have, "Fracture and Fatigue Control in Structures -
Applications of Fracture Mechanics" by Rolfe and Barsom (from Kansas
City, I believe.  Rolfe was involved in investigating the hotel failure
there.), is now nearly 25 years old.  I'm sure there are other, newer
ones available today if you wish to research the subject in more detail.

				Regards,

				H. Daryl Richardson

syed faiz ahmad wrote:
> 
> Gentlemen
> 
> These episodes on steel construction in sub-freezing zones reminds me of a
> title picture on a text book on  FRACTURE MECHANICS. The picture showed a
> ship, somewhere in the arctic, visibly split into two, with a grafitti on,
> "oh! shit".
> 
> Does it throw any light on the issue? Regards,
> 
> SYED FAIZ AHMAD; MENGG, Mem ASCE
> SENIOR STRUCTURAL ENGINEER
> SAUDI OGER LTD
> RIYADH, SAUDI ARABIA.
> 
> >From: h.d.richardson(--nospam--at)home.com
> >Reply-To: seaint(--nospam--at)seaint.org
> >To: seaint(--nospam--at)seaint.org
> >Subject: Re: Steel Building in Alaska
> >Date: Mon, 18 Jun 2001 17:17:51 -0600
> >
> >David,
> >
> >       You're much more likely to have foundation problems than steel
> >problems.  It's imperative that you get good professional geotechnical
> >information that's specific to each site.  Foundation designs and
> >construction techniques are very much different in Alaska and Canada
> >than they are in California.
> >
> >       You also may have problems with your building envelope details since
> >you have a much greater temperature gradient through the building
> >envelope; but this is not my area of expertise.
> >
> >       For steel it's much like what you are already used to.  We use A325
> >high strength bolts for structural applications, and A7 for anchor bolts
> >except when we need something with higher strength.  The steel
> >specifications we commonly use are CSA G40.21-350W for rolled shapes and
> >CSA G40.21-300W for plate (these are metric designations, the imperial
> >designations were 50W and 44W for yield strength = 50 k.s.i. and 44
> >k.s.i. respectively).  These steels should be available from most U.S.
> >suppliers selling into Canada for little or no price premium relative to
> >A36 material.  For bridges we may elect to use CSA G40.21-350WT, which
> >has specified Charpy values determined at lower temperatures to protect
> >against brittle fracture; but for buildings you shouldn't need to do
> >this.  This WT material may have a price premium and/or minimum order
> >quantities may apply.
> >
> >       Steel can become brittle at low temperatures but this is not usually a
> >problem for buildings for two reasons: structural frames are usually
> >INSIDE of the building envelope and are, therefore not subjected to low
> >temperatures; and buildings are usually not subjected to high impact
> >loading.  There are literally thousands of buildings in Canada and
> >Alaska fabricated from 300W material and A36 material providing
> >satisfactory service.  One of the main differences between the above
> >listed CSA materials and A36 is that the CSA materials have minimum
> >Charpy (impact test) values specified while the A36 does not.
> >
> >       I hope this is helpful.
> >
> >                               Regards,
> >
> >                               H. Daryl Richardson
> >
> >Bob Hanson wrote:
> > >
> > > The Canadian Codes I believe have provisions for steel in cold climates.
> >If
> > > memory serves me you will need to specify steel that has chemical
> >properties
> > > that allow its use at those low temperatures. The problem is some steel
> > > types get very brittle.HTH
> > > Bob Hanson, SE
> > > Torrance, CA.
> > >
> > > -----Original Message-----
> > > From: David Chan [mailto:dchan(--nospam--at)johnmartin.com]
> > > Sent: Monday, June 18, 2001 12:08 PM
> > > To: seaint(--nospam--at)seaint.org
> > > Subject: Steel Building in Alaska
> > >
> > > I am doing some preliminary work/research for a steel building to be
> >located
> > > in Alaska.  I have been told that the temperature can go as low as
> >negative
> > > 60 degress F.  Are there any AISC publications or special requirements
> > > (steel, bolts, welding, etc.) that I should be aware of?  I have tried
> >the
> > > AISC website and listserver archives but could not find anything.
> > >
> > > Thanks in advance.
> > >
> > > David S. Chan, P.E.
> > > Los Angeles, CA
> > >
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