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Re: Long pipeline seismic design

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Chris' advice is good. But another factor to consider is that if you are asking the questions you are asking, you need to get help from someone experienced in the process to at least peer review your work and the criteria developed.  For a sleeper supported pipeline in any significant seismic environment, the displacements can be substantial and your design needs to account for that.  It is particularly important to recognize whether the pipe crosses a fault zone or is affected primarily by ground shaking.  For a reference on some actual behavior at a fault zone, see the attached link for a paper on the Alaska Pipeline in the Denali EQ.
Bill Cain, S.E.
Berkeley CA
-----Original Message-----
From: chrisw(--nospam--at)
To: seaint(--nospam--at)
Sent: Mon, 17 Jul 2006 11:57 AM
Subject: Re: Long pipeline seismic design

On Jul 17, 2006, at 10:02 AM, joraljim(--nospam--at) wrote: 
> What is the criteria for the structural design? Who is supposed to > give the parameters for structural design, the geologist or the > geotechnical engineer? What codes apply here? 
Normally you'd do a multi point response spectrum analysis, although you might start with a single point response spectrum that you'd fiddle to provide a rocking effect. ANSYS does this and probably most general purpose FEA codes. I don't think there's a very good manual approach because the actual dynamic response of a long pipeline isn't much like the static response. The best situation is to have site-specific spectra provided by the facility. These would have been developed by geotechnical investigation, but you want spectra which have been properly smoothed and broadened by people familiar with site requirements for safety-related equipment. Ordinarily ASME or API Codes are used, although seismic requirements in either aren't specific enough to provide loading for every site in the world. 
Christopher Wright P.E. |"They couldn't hit an elephant at 
chrisw(--nospam--at) | this distance" (last words of Gen. 
.......................................| John Sedgwick, Spotsylvania 1864) 
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