Seismic analysis of buried pipe with uniform load F/L

Hello

In buried pipeline seismic analysis is not true. If i can define uniform load as F/L instead of gravity load g can we do seismic analysis in buried pipelines. Also, to find uniform load as F/L, can we use seismic wizard?

Thanks...

You cannot define linearly distributed force on a buried pipe, because Caesar II approach is to assume zero mass properties for the buried elements. Read Caesar II manual and also do a search on this Forum, you'll find interesting older posts on this topic.

Otherwise, you may perform a test to see yourself what you get...

In general, seismic action on buried pipework is evaluated by imposing equivalent thermal expansion loadings, which assimilate soil-pipe interaction-induced strains distribution.

I suggest to have a look in American Lifelines Alliance (ALA) Guidelines for the Design of Buried Steel Pipe.

Best regards,

I think buried pipeline need completely different analysis method: http://bit.do/seismicburied

Zall,

The comments above are correct for the buried piping stress analysis. You have not defined the code that you are using this application, but ALA guidance is the best source for your application in addition to the CAESAR II reference within ASME B31.1 for modelling. You will find the short-cut to the ALA reference.

https://www.americanlifelinesalliance.com/pdf/Update061305.pdf

As Dorin has explained the ALA guideline gives you how to apply the seismic force as a thermal load. In addition to this you need to read the modelling issues within the CAESAR II guides, it is different from the aboveground piping model. You may have to increase the nodes at certain locations to be able to see the behaviour of the piping.

The more you read guidelines on the issue you will have more question in mind. Fault lines are going to be an issue if you are dealing with long distance pipeline. They may need special attention.

It seems that you are a beginner for the buried piping analysis, I wish you passion and good luck.

Thank you for your replies.

I modeled line and defined soil properties. But all cases failed even hydrostatic and sustained load case. I couldn't solve why it was failed in hydro case and sustained case. Failed locations are generally large bends and elbows.

When you say that you modelled, it is important how you modelled the buried piping. Especially, bends, elbows and close lengths to these fittings need to have sufficient number of nodes in the model. Span lengths between nodes on the buried pipe are have to be in line with CAESAR II user guide or shorter. If you have already done this, check units of your inputs, especially the densities.

After checking you still cannot solve the problems you are facing you need to send your model to the Coade to ask for their help.