Damaged Steel Beam, Top Flange Bent During Install 2

[bigmig]

I walked out to my job site the other day and noticed that a steel member in a truss I designed has a dent in the top flange (see photo).
Any advice on references for fixing this or "did that regretted it" would be appreciated.

 

[KootK]

Unless it's exposed, I probably wouldn't worry about it. If it's a chord that will always be in tension, the dent will tend to straighten out under load. Under compression loading, the dent is probably too close to the panel point to seriously impact strong axis buckling capacity unless the design relied upon a continuous, multi-span buckling shape. If the bottom chord sees compression and is not braced laterally at the panel points, you may need to worry about weak axis buckling capacity.

A possible fix might be to weld a short cover plate over top of the dented flange to replace its strength and stiffness.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[TehMightyEngineer]

Similar to what KootK said. You could also try to heat-straighten it as an acceptable solution.

There are a number of papers and articles on this. Google for more but here's one long one from the FHWA:

http://www.google.com/url?sa=t&rct=...cd=2&cad=rja&uact=8&ved=0CCgQFjAB&url=http://

http://www.fhwa.dot.gov/bridge/stee...=bg0KkSL4hdM1Rcm65d0feg&bvm=bv.84607526,d.eXY

Also:

http://www.eng-tips.com/viewthread.cfm?qid=106922

Maine Professional and Structural Engineer.
(Just passed the 16-hour SE exam, woohoo!)

 

[KootK]

Nice reference TME. If I was the owner, I'd opt for the heat straightening.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[TehMightyEngineer]

Thanks KootK. Downloadable version for your eLibrary:

http://www.fhwa.dot.gov/bridge/steel/heat_guide.pdf

As KootK pointed out, assuming the beam only yielded and doesn't have cracks or major discontinuities, and is a tension member with limited bending; you likely will find it's acceptable as is or with minor reinforcement (cover plate). Heat-straightening would only make sense to me if it was a compression or major flexural member, or was required to be exposed in some way.

Maine Professional and Structural Engineer.
(Just passed the 16-hour SE exam, woohoo!)

 

[KootK]

How did you know about the eLibrary?? Do you have any sense for the cost of heat straightening? If it's reasonable, I might just adopt is a my default position.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[TehMightyEngineer]

You strike me as the kind of person who has a carefully organized drive of downloaded pdfs. I know I do.

Heat straightening costs vary wildly, mostly due to contractor inexperience and the complexities involved in the repair process. We utilized it twice on large truck dumper frames where the main girders had warped (one due to collapse, the other due to overload). In that case it was clearly cheaper than rebuilding the frame from scratch.

For a simple beam like the OPs, my gut says that cover plates or similar repairs are cheaper. However, heat-straightening is essentially just controlled heating and cooling and is almost comparable to pre-heating of welds. You could likely make a rough comparison using data for pre-heating and I bet you would get close. If you look at one of the example in the FHWA guide they show an extremely distorted bridge girder which I wouldn't have given another thought it they went to replace it but someone must have figured that heat-straightening was more cost-efficient. Perhaps that had something to due with road closures, though.

For what it's worth it's my bosses go-to method when someone dents a beam or column and I have adopted a similar approach.

It's worth noting that extreme damage or mistakes made during heating can ruin the beam, thus there is a risk that you could attempt to heat-straighten a beam only to have to replace it in the end.

Maine Professional and Structural Engineer.
(Just passed the 16-hour SE exam, woohoo!)

 

[TehMightyEngineer]

Also to consider in the cost is jacking or clamping arrangements, staging, and any attachment hardware for the jacks/clamps.

Maine Professional and Structural Engineer.
(Just passed the 16-hour SE exam, woohoo!)

 

[KootK]

Lucky guess. I catalog my PDF engineering files in an Access database. The "Link" buttons fetch the files from my Dropbox folder and display them before my eyes at my leisure. I have three children and, thus far, none of their achievements even remotely compares to this.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[TehMightyEngineer]

Hah, poor kids.

Beats my method of just sticking PDFs in folders under their topic.

Maine Professional and Structural Engineer.
(Just passed the 16-hour SE exam, woohoo!)

 

[TehMightyEngineer]

Maine Professional and Structural Engineer.
(Just passed the 16-hour SE exam, woohoo!)

 

[3DDave]

OT:

The answer to the file organization business is - Wiki. They are typically built over a database, so can be handled that way, but also expose links to other information as well as content searches. For example, I've used it to record drawing contents, which include drawing notes. I can link directly from notes to related information, such as specs, and because the back-links are automatic, when a spec is viewed I see all the documents that refer to that spec. Because forward links are created ahead of creating the linked page, it means that there's no need to stop and deal with extraneous information until it is required, at which time -all- forward links become live without having to revisit all the pages that are home to those links.

I'd give up CAD if forced to choose between CAD and the Wiki.

The main development over other schemes is that in the Wiki I can record where the info came from and why it was important. As far as I'm concerned folders is where information goes to die.

 

[bridgebuster]

TME,

I use the same method of filing as you. I have over 10K files and the system generally serves me well. I also have an Excel sheet on which I list certain items or topics so I can easily retrieve them.

 

[XR250]

KootK - you clearly are neglecting your kids if you have time for a project like this :>
Just like Ted, mine are store in a folder.

 

[KootK]

Yes. I actually live in constant fear over it. I used to be something of an Access programming rock star. Now, I can barely handle updating my own database to work with new Access releases. Eventually, the wheels will come off and I'll just have a bunch of oddly named files in a very loosey goosey file structure.

@3DDave: thanks for your input. My IT department has actually been trying to talk me into something like that but I've been resistant. I clearly don't know the technology well enough. Can you point me to anything that might enlighten me?



I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

[wadavis]

Heat straightening, from the picture: 8hr on site, two men with minor equipment and a manlift, apply local rates for one skilled labor and one helper. Source: My time holding the torch.

I'm seeing that heat straightening is coming up frequently in this forum, do you guys think there is a demand for specialists preparing engineered heat straightening procedures and consulting?

Structural E.I.T., Alberta