Original question from jacky89:
Autopipe currently supports ALA guideline seismic wave propagation analysis. However, does it support analyzing fault line crossings per the same guideline? If not, will this feature be supported in an upcoming release?
Would it be appropriate to design fault line crossings by applying an offset to the pipeline? Are there any other way to model this?
Is there anyway to calculate pipe strain for buckling analysis?
AutoPIPE provides the ability to the user to be able to generate soil stiffness properties using the method provided in ALA guideline (ASCE 2001: Guidelines for the Design of Buried Steel Pipe). Using the imposed support displacement with a buried pipe model, it may be possible to model a fault line crossing. There is no specific workflow currently in AutoPIPE to model a fault line crossing.
You can model a buried pipeline by provide the soil stiffness values in four directions, and then apply imposed support displacement values (e.g. If your total fault line displacement is say 10", you may start by providing 1" imposed support displacement from one piping node, increment that until you reach 10" total displacement). You may continue the imposed displacement after the fault line crossing keeping it at 10" until a virtual anchor is reached.
The displaced model would look something like the one shown below:
For your second question, can you please post it separately and provide a little background on the issue?
I hope this helps.
Regards,
Bilal Shah
In the past few years, the importance of seismic adequacy of the water pipelines has seen an enormous rise in municipalities and water agencies in the US. One area of analysis that has been frequently requested by water utilities owners are seismic fault line crossing and other seismic induced ground displacement conditions in their transmission and distribution mains.
The ALA guideline (ASCE 2001: Guidelines for the Design of Buried Steel Pipe) Section 8.3 and 8.4 talks about using finite element analysis software for analyzing fault offsets. The acceptance criteria is based on pipe strain and not stress per Appendix A, page 66 of the same document.
www.americanlifelinesalliance.com/.../Update061305.pdf
Design Guideline for Seismic Resistant Water Pipeline Installations Part 2 Section 7.4 provides the finite element analysis design methodologies for landslides, liquefactions, and fault line offsets.
www.americanlifelinesalliance.com/Products_new3.htm
Can this feature be included in future versions of Autopipe? This is a hot area in the water industry that is really picking up, especially after the industry's awareness of seismic hazards after the 2011 earthquake in Japan. Having this feature will really make Autopipe standout from other similar piping software.
Jacky,
Thank you for your detailed response and the references. I assume you are referring to the Longitudinal strain from ground moments criteria from Appendix A. This feature suggestion is interesting and after going through the referenced documents we can evaluate it's inclusion in a future version of AutoPIPE.
Any further input from your end would be much appreciated.
HI Bilal,
Yes longitudinal strain is what I am referring to. Would be wonderful if you guys can include the finite element section of the ALA in Autopipe!