On Wed, 18 Mar 2009 18:25:43 -0700, Stuart Fields wrote:
"Ned Simmons" wrote in message
...
On Wed, 18 Mar 2009 08:57:36 -0500, Tim Wescott
wrote:
On Wed, 18 Mar 2009 11:57:21 +0000, _ wrote:
One of the projects involves both re-doing the garage and lifting a
ford 4-cyl motor out of a car. There's a fellow selling an I-beam
locally, 13 feet long, 8 inches deep, 4 inches wide (no web thickness
specified).
This would span the garage nicely - could I rely on it to not bend
if I
hook up a hoist to the centre and lift that motor? Supported on the
ends only...
There are engineering tables for that sort of thing. I don't know
where the right place to look is, but that's all been reduced to "look
it up and run a couple of numbers".
The tables are in the AISC Steel Construction Manual, but first you
need to know which table or chart to use and how to apply it
appropriately. There's lots of jargon and abbreviations in the data
that the user needs to interpret and then determine whether any of it
is relevant to the case at hand.
For example, the charts and tables assume a factor of safety for
structural applications which is much lower than the practice for
overhead lifting.
As Lloyd pointed out, mount that sucker so it absolutely positively
cannot turn on it's side or fall off of it's supports.
That's a good start. g
--
Ned Simmons
Ned: Baumeister and Marks Standard Handbook for Mechanical Engineer
that I have just about ground into unreadable by repeated usage, and I'm
not a mechanical engineer, has a table 2 on page 5-32 that shows a
simply supported beam which means the ends are only restricted
vertically and not welded into a vertical column max deflection is:
f
=
(W* (5* L^3))/(384* E*I) W= weight applied to center of
beam in pounds
L= length in
inches
E= 29* 10^6
if
it is steel
I = the
moment
of inertia of the I beam section. Note the way to calculate this is
found on page 5-38 of the same book. The drawing is a bit messy but the
I factor does depend on the web thickness. It is a no brainer if you
have the picture from page 5-38 and all the dimensions from the I- beam
The moment of inertia may depend on web thickness, but you'll find it
doesn't depend _much_ on web thickness.
--
http://www.wescottdesign.com