Stiffness of Buried FLexible Pipe

[stanier]

I am looking for references that cover the calculation of the stiffness of a pre insulated plastic pipe material.

The ring bending moment of inertia is required as is the location of the neutral axis. From this data I rpesume one can calulate the stiffnes using the various moduli of the core, insulation and outer sheath.

Neither Moser or Watkins cover this in their buried pipeline books, no standards appear to cover this apsect either.

Has anyone in the district heating field had to do this type of design where the criteria of stress, strain, deflection, combined loading and buckling are determined for external loads such as wheel loading, impact loading superimposed loads and soil loads?

Apologies for posting on two forums but I need an answer from as many people as possible.

 

[LCruiser]

Check the NRCS website - maybe TR8? I don't remember which...

 

[sqrt]

Let me see now, civil engineers developed the beam on elastic foundation theory back in the railroad days (when civil was king). The theory was extended to cover hooping stresses in pipes etc..

It would seem that your dealing with a beam on elastic foundation, as a pipe and a as a beam? Sounds interesting.

http://www.cpchem.com/enu/performance_pipe_engineering_manual.asp

 

[dicksewerrat]

Pipe stiffness is talked about in the Plastic pipe Institute web site. I think it is PPI.com. Pipe stiffness is a measurement of deflection at a specific load. Not very useful in my opinion. And the person asking for it probably can't calculate it either. Disregard the insulation.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[mrwhiteOH]

See A.P. Moser text on "Buried Pipe Design" by McGraw Hill or Pipe Mechanics (I think this is the title) by Watkins

 

[stanier]

mrwhiteOH

Thanks, I have both of these books to hand however they do not provide the information that I seek. i will end up with some non linear FEA program to undertake this matter.

DickSewerrat

Stiffness is one of the important criteria in the design of soil/pipe structures. In the design the computation of the stress, strain, buckling, deflection and combined loading criteria in undertaken.

GRP is sold under stiffness ratings as it is difficult to define the properties of such an anisotropic material.

Suggest you read AS 2566, BS7199 or ISO 14692 or the references given previously