Utilizing ASTM F1216 for Composite Pipe Repair Systems

[blaxabbath]

As more FRP manufacturers are moving to pipe installations with carbon fiber composites, the typical design approach has been to run the F1216 CIPP calculations with the FRP properties (I also utilize the ACI 440 reduction factors but find that it generally provides little difference in the final design). While I think this is a 'good enough' approach, there are some considerations that make me think that an FRP-specific calculation should be pursued as FRP is sticking around as a viable long term internal pipe rehab solution.

The specific consideration that has me scratching my head has to do with the fact that the CIPP does not intimately bond with the pipe wall. As such, considerations are taken into account with regard to the voids where the pipe and CIPP are not bonded (which makes sense). However, it is difficult to look at a pipe and say it is anything other than fully deteriorated or partially deteriorated. So I find myself staring at the calculations wondering if there really is a better way. Does any else have any experience analyzing the 1216 equations for use with repair methods other than CIPP?

Composite Strengthening Systems, LLC
Turnkey Design and Installation Services
Coming Fall 2012: COMPOSITE-STRENGTHENING.COM

 

[dicksewerrat]

If you are using F1216 Fully DET., then you have the stand alone liner or pipe. Do you have all the test data or are just using manufacturuers data? what numbers are you plugging in for the physical properties of your FRP ?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[blaxabbath]

dick,

I am working with the manufacture data as is derived from appropriate testing. So I know the values I am plugging are correct but your point about the stand alone liner or pipe is where, I think, I need to elaborate.

With the exception of ASME PCC-2 testing, which allows for a full steel pipe to erode away by design, civil applications (using ACI 440 as the guideline) require the existing structure to maintain it's own capacity to a certain extent, and then the FRP is bonded to the structure to provide additional reinforcing. In the case of a concrete column or slab, for example, the design expectation is not a fully deteriorated substrate. Rather, the existing damage is appropriately repaired and then the system is installed.

To clarify, I don't feel like the issue is that the equations do not apply to composites -- I do and trust the output. Just from an application standpoint, I feel there is an inconsistency where we cannot design stand alone FRP systems for structures but we can for pipes. I don't really know if this is right or wrong (they both seem to work) but I wonder if anyone else has seen it the same way and, if so, if they had any comments.

 

[dicksewerrat]

I work with pipes only now. ASCE is working on some new wats to design liners. should be done in a year or so. Relating to structural reinforcing, can you look at the individual members as a composite. Old slab repaired to original and FRP reinforcing. My guess would be to put the FRP where you need more tensile strength. I don't think there would be much advantage on the compression side.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[blaxabbath]

dick,

You are correct about the lack of compressive value in the FRP designs. They really provide the most bang for their buck in pressure situations where the external loading isn't greater than 6'-12'.

I learned this week that the AWWA provided a sizable grant to a firm (I can't recall the name right now) to essentially study this situation and, within the next couple years, provide an FRP standard for internal PCCP lining so the CIPP standard won't need to be used as the 'best available' option.

Composite Strengthening Systems, LLC
Turnkey Design and Installation Services
Coming Fall 2012: COMPOSITE-STRENGTHENING.COM