Extren and other pultruded FRP products

[DaveVikingPE]

Has anyone designed anything using Extren?

I've been aware of the material for many years and have the Morrison Molded Fiber Glass design manual, but other than that and anecdotal info, I've never met an engineer who actually specified it in a project.

Anyone here familiar/has experience?

 

[LPPE]

Dave- I tried using it on a few residential designs, but my boss said no. I figured it would be easier for the guys to work with it in the field (lighter, easier to cut than steel), but my boss said no ones ever used it before, so dont start now.
"Yes, sir."
So I cant help you. Sorry.

 

[redhead]

Dave:
We have used it on a number of occasions in process facilities, particularly for catwalks and pipe support structures. Strongwell Corp. has a very complete design manual. Contact them at

http://www.strongwell.com/,

or
540/645-8000.

 

[DaveVikingPE]

Thanks, redhead!

Checking out Strongwell's history... they're related to MMFG...

For catwalks, did you use just the FRP grating or did you design/build the structure completely from FRP, including connections? What did you like/dislike about the material during construction? Did your customer raise any concerns when presented with the design?

Thanks!

 

[JedClampett]

I've used CorLight shapes by IKG. These were used to support FRP grating in a sewage lift station where hydrogen sulfide exposure might get severe. I try to avoid using these whenever possible because of the lack of code guidance.
As far as connections, I used stainless angles and bolts and tried to mimic AISC connections as much as possible.

 

[Taro]

Some thoughts...

One of the main design considerations for FRP structures is deflection. The material is very strong, but has a low modulus of elasticity. You will need deeper members as compared to steel to avoid unacceptably bouncy floors.

Other brands that have useful catalogs are Fibergrate and Pultex.

Discuss the proposed system with the building official (if there is one) early on in the design. There doesn't seem to be any nationally recognized standard for FRP design, so the building official will need to buy off on it.

 

[redhead]

Dave:

We used the structural shapes, handrails and the grating for both catwalks and stairs. Main connections were mechanically fastened. Handrail sections were prefabed and used epoxy adhesives. Material choice came from the client.
We were not involved in the installation stage, so unfortunately no feedback.

 

[DaveVikingPE]

How about embeding Extren in concrete?

 

[redhead]

I haven't any experience with plastics embedded in concrete. Suggest you ask "Strongwell" if they have any recommendations.

 

[rd78]

Dave-

Any new info on this? I can't get a comfort level with connections. How does the low crosswise strength come into play?

Rick D.

 

[vooter]

Rick,

1. I did a lot of research on structural FRP connections before the whole idea was canned (due to a more economic alternative) by my superiors. However, I kept a lot of the stuff, like:

"Aspects of Joining Pultrusions"

http://www.pultron.co.nz/frames/mainframes/techmain/papermcgrath.htm

and

"Connections of Fiber-Reinforced Polymer (FRP) Structural Members: A Review of the State of the Art"

http://ois.nist.gov/nistpubs/technipubs/recent/search.cfm?dbibid=6362

and this pretty amazing site
"Advanced Polymeric Composites for Structural Applications in Construction"

http://www.cosacnet.soton.ac.uk/presentations/presentations.htm

2. I'm somewhat convinced that connection design in FRP has to be superduper conservative since the failure modes have everything to do with how the fibers are oriented, etc., etc. The Cosacnet website has tons and tons of papers on all manner of distructive testing; so much so that the FRP sheet pile manufacturer should've done a better job convincing me that splicing their product would've been not as hard as they made it out to be.

3. I drove by the Strongwell factory in Bristol, Virginia this November; it's right there on Route 81, on the way to Tennessee... I felt like stopping by to "pick up" a W8x10, but decided not to, since it was Sunday and they were closed.

 

[MotorCity]

DaveViking,

I have specified Extren many times with much success. The technical department at Strongwell has also been very helpful in the past.

I have designed FRP structures mostly for use at water treatment facilities. The following should be considered before designing with FRP:

1. Strength depends on the orientation of the pultruded fiberglass strands.

2. In can be easily corroded in certain chemical environments (check with manufacturer).

3. Its material properties become less favorable quite rapidly as the temperature increases.

4. Although labor is usually cheap (it is much lighter than steel and special tools are not required), the price per pound for the material is more expensive than stainless steel and aluminum.

5. It bonds well when embedded in concrete (similar to FRP reinforcing bars)

As a final note, material properties for FRP differ among manufacturers so be sure to follow their recommendations consistently.

Good luck.

 

[rd78]

vooter-

Thanks for the tips. I wish I could access the connections papers at Cosacnet, but the links don't work. The other papers are interesting, but a little off topic.

One of the things I'm interested in is the effect of low crosswise strength. I believe that affects both the connections (edge distance, etc) and the critical local buckling for the members.

I talked to an engineer at Strongwell, who said yes, that's true, but the engineering is proprietary.

I wonder if anyone knows the strength of materials background for the compact section/ unstiffened element criteria in steel design. Maybe there's an adaption where one could derive the effect of low crosswise properties.

Thanks.

Rick D.