FRP Repair/Strengthening

[abusementpark]

Does anyone here have experience in using FRP to repair/strengthen structural elements? I am curious in which applications has it been most prominently used with success.

Any info or reading material recommendations are greatly appreciated.

 

[bridgebuster]

One of my coworkers did a project involving strengthening of three bridge piers - multi columns with cap beam - using FRP.

The R J Watson Company was very helpful. They provided a lot of engineering and estimating support.

One thing to keep in mind: FRP isn't a concrete repair; it's used for additional strength. The concrete has to be repaired using conventional means

 

[Qshake]

Agree with bridgebuster. My experience is that Watson's company has the market on this presently. We've worked with them in the past on concrete strengthening, shear and flexure.

I can't think of anyone else right of hand. But I'venot searched the internet either.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[asixth]

We were looking at strengthening a carpark with FRP one-time but there was sufficient suggestions from both ACI440 and the Sika CarboDur Design Procedures to say that the structure must have sufficient capacity without the influence of FRP before externally bonded FRP can be used to strengthen the structure.

There was a bridge locally to me that was strengthened using FRP and a report was written on the topic by a local university. I have been looking at doing some research into the use of FRP but have not had the time to do any sufficient investigation into it.

One of the biggest hurdles I see myself facing is the calculations of the initial strain of the concrete cross-section when the FRP is applied.

http://eprints.qut.edu.au/26889/

 

[JohnWylie]

For my master's thesis, I did experimental testing on unreinforced masonry walls reinforced with near surface mounted (NSM) carbon FRP. I focused on out-of-plane bending, but the method works for in-plane also. There was a forum recently were I posted three (3) links for my thesis and two (2) journal papers. Feel free to look at them.

http://www.eng-tips.com/viewthread.cfm?qid=257835&page=1

I did not develop design equations using the NSM method in my thesis. I simply was demonstrating that the NSM method increased the out-of-plane bending resistance and ductility. The NSM method was equally or better than using external methods. Additionally, the NSM method preserves the aesthetics of the structure.

Attached below is another paper by some researches in Australia that have developed some design equations. They primarily focus on URM walls, but it might help you.

 

[HgTX]

http://144.171.11.40/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=279

Hg

Eng-Tips policies: faq731-376

 

[JoshPlumSE]

My imression was that the Fyfe company (at least here in California) were the guys doing most of these projects.

http://www.fyfeco.com/

I've never heard of Watson, but I haven't looked into this for a number of years.

I've seen this used to strengthen un-reinforced (or under reinforced) masonry buildings as well as to provide better confinement for concrete columns.

 

[Qshake]

Watson and Fyfe are (or were) related companies. RJ Watson started from an age old bearing company, Watson Bowman and has morphed into some hi-tech bearings (hi load types for bridges) that are polymer based.

Seems Ed Fyfe and Ron Watson teamed up and developed some products and actual applicators.

Hexcel-Fyfe was a early Fyfe company and seemed to predate the Watson teaming.

Just trying to remember how it all fit together. I've worked with both companies. Good people.

Having had a course on Infrastructure Strengthening with FRP and other composite mechanics I can tell you that the main industry for FRP strengthening is parking garages, followed by buildings and then the old conservative bridge industry. The most common type of retrofit is flexure where straps are appled at the bottom of beams. In some cases, the straps are also assisted by U shaped applications. The second common retrofit is shear strengthening with u shaped straps or continuous u shaped retrofit. In the bridge industry round concrete columns were being retrofitted in California in the early 90s.

As was pointed out earlier, to strengthen an existing member ACI requires that it meet a certain load requirement to ensure that is it not only practical to retrofit but safe to do so.

Among other books, Larwence Bank (Un of Michigan) has a very nice text.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[abusementpark]

What services do companies like Fyfe and Watson provide? Do they provide the material and assist with the engineering?
Or do they do all the engineering and provide the material?

Qshake, why is it so popular in parking garages?

 

[enginerding]

We are actually using this for the first time. We are going through Fibrwrap Construction. They are closely related to Fyfe, but I am not sure the relationship.

Fibrwrap is the contractor. Fyfe is designing the actual reinforcement per the "required additional strength" in shear and bending that we are providing to them.

They are submitting all calculations and data sheets to us for review, but they are providing the sealed engineering.

 

[Qshake]

Pretty sure that Fyfe is the material supplier and consultant, whereas Watson provides the labor for the overall application. These sorts of things are still proprietary, so one supplier is typically hooked up with one applicator.

Popularity in parking garages comes from both need and a less intrusive solution. The need is obvious, parking garages take a beating from the weather and loading plus whatever salts cars track in or are in the air. Need also covers older garages that need to strengthened for today's loads. The less intrusive application is ideal because owners what their car spaces for rent and FRP takes very little time with very little equipment to complete. No tearing down interior building material to get to the concrete beams they're right there. So it's low risk for the contractor.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[Ron]

Have experience with Sika Carbon Fiber system (Carbodur). Worked well on deteriorated concrete floor system and on elevated rapid transit application for pre-cast/pre-stressed beam elements.

 

[asixth]

This is something that the Sika Australia guys gave me. Let me know if you need some more technical resources with any design aspects.

 

[hokie66]

What is done about restoring the fire rating of concrete structures strengthened with carbon fibre? The new reinforcing is exposed.

 

[Qshake]

hokie66 - While I cannot specifically address what is done, I can say that this was an issue keeping FRP out of the retrofit/rehabilitation for some time. Today's FRP applications are developed with matrix materials that have better fire resistant properties. As to the specifics you'd have to talk to a rep.

Regards,
Qshake

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