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RE: Steel column flange damage repair

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Title: RE: Steel column flange damage repair

In a complex application, heat straightening is an art and there are a few experts who can serve as consultants (Richard Avent, Dan Holt, Charles Roeder and Jeff Post come to mind). An expert will likely be needed on a very complex job, unless the fabricator's personnel have experience.

I know of one case where a long-span bridge girder got mangled in the roll, separation, fall and plunge into the river below where it was being installed. Other than being twisted, distorted and generally all banged up, there was nothing wrong with the girder. (-: The schedule, needs and economics of the job were such that heat straightening the fallen girder (after they fished it out) was a much more feasible approach than fabricating a new girder. If you had not known that plate girder had fallen and plunged already, you'd have sworn it was a new girder when the heat straightening was completed. Even the expert hired learned some things on that job.

However, for a job that's as simple as taking a dimple out of a column flange, the various papers that have been written by those experts can be used quite successfully by capable fabrication personnel. Unless I'm mistaken, the case that generated this discussion seemed about that straightforward.

A few of the papers that are available are as follows:

    "Engineered Heat Straightening", R. Richard Avent, Proceedings of the 1995 AISC National Steel Construction Conference, AISC, Chicago, IL.

    "Flame Straightening Technology", Daniel J. Holt, Proceedings of the 1995 AISC National Steel Construction Conference, AISC, Chicago, IL.

    "Designing Heat Straightening Repairs", R. Richard Avent, Proceedings of the 1992 AISC National Steel Construction Conference, AISC, Chicago, IL.

Dave Ruby also pointed out that a little heat and brute force (a jack) can be used to straighten the flange.

Regarding the potential need for reinforcement, I wonder why any reinforcement would be required if the flange has been realigned as successfully as it can be. Personally, I'd only consider adding reinforcement if that could be use in place of (and were cheaper than) heat straightening; or if the straightened flange still had waviness outside of ASTM A6 tolerances after straightening.

Charlie

-----Original Message-----
From: Paul Ransom [mailto:ad026(--nospam--at)hwcn.org]
Sent: Monday, December 11, 2000 11:05 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Steel column flange damage repair


David Ruby
>From your experience, can you provide any guidance as to when one might
use heat straightening vs heating with mechanical realignment?

You imply that there are relatively few people who are adequately
experienced at heat straightening so I assume that this is a very
expensive proposition and, therefore, not appropriate for the typical
damaged column in an industrial structure.

What degree of straightening might be achieved by each method? Would it
be possible to reasonably determine in advance when additional
reinforcing might be required?


--
Paul Ransom, P. Eng.
Civil/Structural/Project/International
Burlington, Ontario, Canada
<mailto:ad026(--nospam--at)hwcn.org> <http://www.hwcn.org/~ad026/civil.html>

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