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Re: big dig structural failure - epoxy anchors overhead supporting gravity

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(it was written somewhere that the ceiling was that heavy to prevent vibrations)
Whoever wrote that may have been looking for an excuse. Additional mass does not prevent vibrations. Vibration occurs when you have a mass supported elastically. More mass reduces the system frequency, but tends to make the amplitude higher for a given excitation and increases the dynamic loading. Additional mass makes the situation worse, not better.

Christopher Wright P.E. |"They couldn't hit an elephant at
chrisw(--nospam--at)skypoint.com   | this distance" (last words of Gen.
.......................................| John Sedgwick, Spotsylvania 1864)
http://www.skypoint.com/~chrisw/


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