# RE: Question on Spirals in Columns

• To: "'seaint(--nospam--at)seaint.org'" <seaint(--nospam--at)seaint.org>
• Subject: RE: Question on Spirals in Columns
• From: Eric Green <egreen(--nospam--at)exponent.com>
• Date: Tue, 12 Mar 2002 09:39:26 -0800
```no when i pull on the hoop it will be touching on the other side of the
earth. This is a rigid string in the form of a hoop, right :-)?

Eric Green, MS, PE
Managing Engineer
Exponent® Failure Analysis Associates®
10899 Kinghurst Drive, Suite 245
Houston, Texas 77099
egreen(--nospam--at)exponent.com
281-983-4018 Direct
281-983-4000 Office
281-879-0687 Facsimile
>

-----Original Message-----
From: Bill Allen, S.E. [mailto:Bill(--nospam--at)jrma.com]
Sent: Tuesday, March 12, 2002 11:34 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Question on Spirals in Columns

Wouldn't that be 1/(2*pi)?

OTOH, why would you have to increase the length of the string at all?
Doesn't the string have enough elasticity to stretch? After all the strain
would only be 3*10^(-9).

Bill Allen, S.E.

||-----Original Message-----
||From: Eric Green [mailto:egreen(--nospam--at)exponent.com]
||Sent: Tuesday, March 12, 2002 9:07 AM
||To: 'seaint(--nospam--at)seaint.org'
||Subject: RE: Question on Spirals in Columns
||
||
||It depends. Is your deck of cards thicker than 1/3.14159 inches?
||
||Eric Green
||
||-----Original Message-----
||From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com]
||Sent: Tuesday, March 12, 2002 10:55 AM
||To: seaint(--nospam--at)seaint.org
||Subject: RE: Question on Spirals in Columns
||
||
||Glen Pappas made an excellent observation on the function of spiral
||reinforcement.
||
||As an illustration of the effect of strain on effective
||confinement, the
||following puzzle is offered:
||
||Assume the earth is a perfect sphere and a string is placed around the
||sphere
||at its equator.  If you increase the length of the string one
||inch (1"),
||would you be able to slip ordinary playing cards under the
||string around the
||
||entire circumference?
||
||A. Roger Turk, P.E.(Structural)
||Tucson, Arizona

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