To: "SEAOC Newsletter" <seaint(--nospam--at)seaint.org>
Subject: Re: Horizontal vessels-Friction forces
From: Christopher Wright <chrisw(--nospam--at)skypoint.com>
Date: Fri, 2 Mar 01 16:20:33 -0600
>Their reason is that the vessel
>moves on the sliding end (and, probably on the fixed
>end also because the hole diameter on the fixed end is
>larger than bolt diameter)and, any friction force that
>may develop is so quick and instantaneous that the
>bolt will not experience it.
That's not right. The friction builds up slowly, just as though the
vessel were fixed. At the point where the fixed end load equals the
normal force times the friction coefficient, the vessel starts to slip.
The sliding friction force, usually less than the static friction,
actually is almost instantaneous because the slip relieves the load.
Your approach sounds fine. I expect you get into the same situation with
bridges where one wnd is more or less fixed and the other slips as
necessary. My personal preference is to fix one end (round bolt holes)
because it seems like a good idea keep the vessel in one place. You might
also want to check the vessel wall for the lengthwise forces (which
impose local shell bending loads) and piping reactions which build up
when the vessel slips.
Christopher Wright P.E. |"They couldn't hit an elephant from
chrisw(--nospam--at)skypoint.com | this distance" (last words of Gen.
___________________________| John Sedgwick, Spotsylvania 1864)