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# RE: NATURAL FREQ OF CANTILEVER PIER

• To: <seaint(--nospam--at)seaint.org>
• Subject: RE: NATURAL FREQ OF CANTILEVER PIER
• From: "Foy, Warren" <Warren.Foy(--nospam--at)mhgrp.com>
• Date: Tue, 28 Dec 2004 13:18:51 -0500

Rich,

From "Introduction to Structural Dynamics" by John M. Biggs, the formula for the natural frequency of a cantilever beam is:

[(0.597xpi)^2/l^2]/(sqrt(EI/m)

Feel free to call me if you like.

HTH,
Warren Foy

 Warren S. Foy, P.E.Structural Design ManagerThe Mason & Hanger Group Inc.

300 West Vine Street, Suite 1300
Lexington, KY 40507-1814
office: 859.252.9980
direct: 859.280.3572
fax: 859.389.8870
web:
http://www.mhgrp.com

-----Original Message-----
From: Rich Lewis [mailto:sea(--nospam--at)lewisengineering.com]
Sent: Tuesday, December 28, 2004 12:08 PM
To: seaint(--nospam--at)seaint.org
Subject: RE: NATURAL FREQ OF CANTILEVER PIER

I guess your assumption is wrong.  I’m not sure what I am looking for.  Is this the equation for a pendulum since it is a concrete pier?  Would this be some kind of equation that takes into account the length and stiffness of the pier?  Does someone have this equation they could post?

Thanks!

Rich Lewis

Lewis Engineering

-----Original Message-----
From: ASC [mailto:ggg(--nospam--at)bigpond.net.au]
Sent: Tuesday, December 28, 2004 10:05 PM
To: Struct EngAssoc
Subject: NATURAL FREQ OF CANTILEVER PIER

I assume you will have no difficulty finding

the formula for a NF of a cantilever. The problem may be

its base, which by nature is deformable.

You will have to increase the basic flexibility by adding translation

and rotation of the base.

Sincerely, Gregory

Analytical Service Pty Ltd
5 Warwick St
Killara/Sydney
Australia 2071
T: 612 9418-1842

From: "Rich Lewis" <sea(--nospam--at)lewisengineering.com>
To: <seaint(--nospam--at)seaint.org>
Subject: Pier Natural Frequency

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I have a requirement to have a cantilever pier supporting a machine to
have a natural frequency greater than 50 Hz.  How do you calculate the
natural frequency of a cantilever pier?

Rich Lewis
Lewis Engineering