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RE: Cylindrical domes

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There are two assumption concerning the structure.  A rigid structure that
takes all the load or a flexible one that allows the soil to support some of
its own weight.  It appears that you have assumed a rigid structure.

For a flexible structure, the soil supports some of its weight based on the
deflected shape of the structure and the soil properties.  This is an
indeterminate solution that is ideal for a computer program.

You can get more information from "Foundation Engineering Handbook",
Winterkorn, Fang, Chapter 23 Buried Structures"

Ron Hill
HILL Consulting Engineering
Birmingham, Alabama  35260 USA
Email: ronhill(--nospam--at)
-----Original Message-----
From: DougSnow(--nospam--at) [mailto:DougSnow(--nospam--at)]
Sent: Wednesday, May 05, 1999 9:12 AM
To: seaint(--nospam--at)
Subject: Cylindrical domes

Hello all,

I have been asked to design a concrete cylindrical dome.  The radius is 35
feet and the apex is 5 feet below grade (A tunnel).  We based our
analysis on a vertical load that increased as the depth of soil increased
a lateral component as an equivalent fluid.  This, of course, created large
stresses for which we designed the concrete thickness and reinforcing.  The
developer says that our results are way too high because we are not
considering the "arching effect" of the soil.  The soils engineer says that
this effect has been documented but that based on the fact that the soil
the structure is fill as opposed to native soil and the fill will be
relatively granular in addition to the effects from vehicular traffic, the
arching effect is minimal. I have spoken with an engineer that says that
got a computer program that can analyze this condition and it's been done a
lot.  Does anyone have any experience with this?  Is this science or more
documented proof that you can write a computer program to say anything you
want to say?

Thanks in advance.

Doug Snow
Snow and Associates
Scottsdale, Arizona