AutPipe Analysis of Buried pipeline

[soil1999]

Hi
Those of u who use AutoPipe software for analysis of buried pipeline. I have simple question:
We are monitoring a pipeline by installing a settlement sensors. and we are getting displacements that we wish to apply in Autopipe to get the due stresses.
Now is there a way to apply these displacement to the pipeline directly. I am asking because with buried pipeline (as I understood), Autopipe will apply the displacement to the springs that simulate the soil-pipe interaction.
Definitely, by applying the displacement to the springs (rather than the pipeline surface), the consequence will be displacement transferred to the pipeline that are much less than the displacement observed by the sensors that are placed on the pipeline.
thanks

 

[BigInch]

If nothing else is possible, which I'm pretty sure is not the case, but admittedly I do not use Autopipe, simply put an artificial load on the pipe that will give you the required deflection at the point in which you have interest. Save that case, run the no artificial load case and add the two together ... provided that the deflection of the two cases have a linear relationship to load, the principle of superpositon will hold.

Any Autopipe experts out there?

 

[ColonelSanders83]

Using AutoPIPE, go to Insert>Xtra Data>Imposed Support Displacment

This will add displacment and roations in whatever direction you please. Simply select the correct load case to combine the displacments with (in your case this would be the gravity case.

Just my two cents worth.



A question properly stated is a problem half solved.

Always remember, free advice is worth exactly what you pay for it!

http://www.ap-dynamics.ab.ca/

 

[ColonelSanders83]

In giving your issue some further thought, be carfull regarding the applications of your loads in your model.

Depending on the location of your measurments in the physical pipline, your burried pipe model may or may not have supports at the appropriate locations (if not you sill need to add some. Furthermore, as burried pipe models only require the use of supports up to the rigid anchor lenths and your support spacings vary over that range, you sill need to interpalate whatever setlement values you have aquired over all the supports in that run (otherwise you end up only displacing one local point rather than the entire run as will happen with settlement). If you are using autopipe soil functions you will need to check that the displacments are correctly deflecting the pipe between run points, if not you will need to redo you model the old fassioned way with multiple supports of the correct stiffness and spacing(modeling the soil) and add an interpolated displacment to each support.

Just my two cents worth.

A question properly stated is a problem half solved.

Always remember, free advice is worth exactly what you pay for it!

http://www.ap-dynamics.ab.ca/

 

[StevenHPerry]

If you haven't already, read AutoPIPE FAQ # 47 in the help file:

"How can I simulate soil settlement on part of my piping system?"

- Steve Perry

http://www.linkedin.com/in/stevenhperry

This post is designed to provide accurate and authoritative information in regard to the subject matter covered. It is offered with the understanding that the author is not engaged in rendering engineering or other professional service. If you need help, get help, and PAY FOR IT.

 

[soil1999]

HI StevenHPerry ColonelSanders83 and BigInch
Based on the Q 47 in FAQ of Autopipe
How can I simulate soil settlement on part of my piping system?

Answer: If the piping system is buried then the imposed displacement at defined node points (with soil) would give the soil settlement profile. In other words, the base of each soil spring is subject to a displacement interpolated from adjacent nodes with imposed displacements. Hence select the range of points and Insert/xtra data / imposed support displacement = settlement value in the U1 case.



THE QUESTION is ; will the imposed displacement be applied to the pipe itself of to the base of the soil spring connected to the pipe. If it is the later case, the field displacment reading taken on the pipe surface at specific node should be applied to a rigid spring at that node .. Correct me if I am wrong.

 

[StevenHPerry]

soil,

It would be best to do a test case to prove out one way or another.

My understanding is that an "imposed support displacement" is applied to the support, not the pipe. If you try to apply a imposed support displacement where there is no support, it will generate an analysis warning. I haven't tried it with soil modeling though.

This is different than other software (CAESAR) with which you can deflect the pipe itself.

Bentley has proved helpful when submitting a trouble ticket through their website or by posting to the Bentley AutoPIPE community. They can definitively answer your question for you if a simple test doesn't work out.

- Steve Perry

http://www.linkedin.com/in/stevenhperry

This post is designed to provide accurate and authoritative information in regard to the subject matter covered. It is offered with the understanding that the author is not engaged in rendering engineering or other professional service. If you need help, get help, and PAY FOR IT.

 

[LSThill]

soil1999 (Geotechnical)& Team Members

Design Guideline for Buried Steel Pipe

This guideline presents design provisions for use in evaluating the integrity of buried pipelines for a range of applied loads. Both new and existing welded buried pipe of carbon or alloy steel fabricated to ASTM or API material specifications and constructed in accordance with ASME B31 pressure piping codes are considered. The following load conditions are addressed: internal pressure, vertical earth loads, surface live loads, surface impact loads, buoyancy, thermal expansion, relative pipe-soil displacement, movement at pipe bends, mine subsidence, earthquake ground motion, effect of nearby blasting, fluid transients, and in-service relocation. The ASME B31 Guideline Committee currently is considering integrating the ALA-developed guidance into its standard.

http://www.americanlifelinesalliance.org/pdf/Update061305.pdf

LEONARD STEPHEN THILL, Oil & Energy Professional

http://www.linkedin.com/in/leonardstephenthill

 

[waterpipe]

I am sorry but this is not intended as an answer.

May I ask the type, the model or a link to the settlement sensors that you have used for measuring the pipe displacement?

I am thinking of measuring / monitoring a pipeline deflection before and after the backfill and your help is really appreciated. Thanks in advance.

 

[soil1999]

waterpipe

sorry for my late reply. in fact we are just doing analysis and not involved in field instrumentations and readings which are looked after by an independent consultant. They just pass us the readings in Excel format.