Need a formula for shear strength of a pipe

[dicksewerrat]

I just got asked a question I hadn't heard before. I need to know the shear strength of an 48" RCP pipe buried 12 feet to invert in what i believe is saturated soils. The pipe will be lined with CIPP. I know the Flex Modulus, Flex Strength and Tensile Strength of the liner.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[rconner]

I think this is maybe not an easy question to answer (at least without more information). I would think the shear strength would be dependent on the many varied constructions available for such pipes and by different specifications/mfgr etc. (e.g. dimensions and amount/orientation of steel reinforcments etc.), as well as the actual condition of the materials now in th epipe wall (at least if this is an existing/old installation?)

 

[BigH]

Dick:
Am sure you did a search - but this is what I quickly found - which isn't "much" for free. Do you think that he might have been talking about the "shear strength" of the concrete (i.e., compressive strength)?

http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA199894

http://books.google.co.id/books?id=...vLkPkM&sa=X&oi=book_result&ct=result&resnum=1

http://www.humes.com.au/ProdsServices/downloads_HMS/CPAA Fact Sheet -Shear strength of FRC Pipes.pdf

 

[Ron]

Dick,
I'm not sure there would ever be enough confinement to mobilize the shear strength of the whole pipe cross section, except possibly within the bell of a joint. But that would also require rigid confinement of the bell, which isn't likely in saturated soil.

Typical shear is not a failure mode for which the pi;e is tested or required to meet under ASTM standards. Pipe load capacity is based on load testing under a crack width criterion.

The Concrete Pipe Design Manual of the American Concrete Pipe Association does not list shear strength as a variable, a parameter, or a criterion for any of the pipe characteristics.

 

[gbam]

Ron makes a good point. Typically RCP strength is based on the d=0.01 based on psi and classification of pipe. There is a section on structural design based on bedding material in the design manual. I am not sure if you can dl a PDF of the manual, I got a disc with the pfd on it.

 

[dicksewerrat]

Thanks Guys. I don't think the Engineer writing the spec. has any idea of what apipe does under load. I'm going to ignore him until I can't. Then maybe I will ask him how to do the Calc.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[Ron]

Dick...good move. He probably wouldn't be able to rebut if you challenged him.