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RE: Hot cambering vs. cold cambering

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Cold cambering in a fabrication shop is accomplished by applying enough force to cause the beam to yield and deform enough so the permanent set is equal the desired camber.  A hydraulic ram is used to deform the beam.  The beam must be supported laterally but the ends must be free to rotate.  Control of the camber requires training and experience.  Concern about excessive camber resulting from the beam trying to return to its initial profile is unwarranted.

 

Cambering with heat involves heating the steel to the point where the strain caused by the heat exceeds the elastic limit strain.  Wedge shaped areas along a beam supported near its ends are heated.  If the beam web is over ½” thick and/or if the flanges are over ¾” thick it is recommended that the heat be applied from both sides.  The heat (1100 to 1200 degrees) must be applied rapidly and uniformly in a continuous zig-zag pattern from about 2/3 into the web out to the flange.  One of the problems with heat cambering is that it takes a very experienced operator to realize what the final camber will be.

 

The above information came from an article Larry Kloiber of LeJune Co. in Minneapolis contributed AISC sponsored lecture.  The article was in a lecture handout entitled Designing for Steel Serviceability.  I don’t know the date of the lecture or the title of the lecture series.  The article was entitled “Cambering of Steel Beams”.  The article was a reprint from some other source because the type and page numbering didn’t match the remainder of the bound notes.  AISC also handed out another article by Larry (Lawrence) at another lecture.  I couldn’t find that one.  I don’t think it was the same article but it may have been.  David T. Ricker also authored and article “Cambering Steel Beams” which appeared in the AISC Engineering Journal, fourth quarter of 1989.  The two articles are fairly similar.

 

In the end, the success of cambering comes down to the experience of the fabricator doing it.

 

Roger C. Davis

Architect

SDS Architects, Inc.

205 N. Dewey Street

Eau Claire, WI 54703

(715) 832-1605

 

-----Original Message-----
From: Ken Peoples [mailto:kspeoples(--nospam--at)lvta.net]
Sent: Thursday, June 24, 2004 7:17 AM
To: Seaint
Subject: Hot cambering vs. cold cambering

 

Greetings,

 

We are bidding a detailing job that has quite a few 60' long W30 and W27 beams cambered 1 1/2".  While the method of cambering has nothing to do with our detailing, the fabricator asked what I knew about cold cambering vs. hot cambering and I had to admit that I don't know much about either.  I would like to find out what there is to know - not only for his benefit but for mine as well.  Is there anyone out there who would like to give me a lesson or point me to a good source on the subject?

 

Thanks in advance.

 

Best regards,

 

 

Ken

 

 

Kenneth S. Peoples, P. E.

 

LVTA

Lehigh Valley Technical Associates, Inc.
1584 Weaversville Road
Northampton, PA 18067-9039

Phone: (610) 262-6345
Fax: (610) 262-8188
e-mail: kpeoples(--nospam--at)lvta.net