defl = (5 x W x l^3)/(384 x E x I)
Yes. For a simply supported, distributed load only.
l is the length in inches
W = w x l or the total load in pounds while w is the load per inch.
E is the modulas of elasticity for wood.
About 2,000,000 (Steel is 30,000,000)
Modulus of wood is listed as 1-2 E6 PSI. Check the exact number for
the wood you are using. Machinery Handbook should have the most
common.
I is the moment of inertia for the beam and is equal to
1/12 x height of the beam to the fourth power or I = 1/12 x h^4
I, for a rectangular beam, is 1/12 x bh^3. Your formula only
works for square beams. b is the width, h is the height. For I beam
or other sections you must calculate I.
=====
Kevin Russert Walsh
Process & Equipment Development Engineer
Thanks for correcting me on that Kevin. It has been years since
I used those formulas. I glanced in the book and took the first
one I found :-)
Paul Lamar
Ok, so how does one calculate "I" for a steel I-beam? (A36).
I have a catalog listing depth, flange width and thickness, and web
thickness.
Problem: size a W beam 50' long, 75 pounds/inch distributed loading
(laterally supported all the way with 2' spacing).
I want to build a hangar/house like Tracy's but 50' x 50', but with steel
structure.
BTW, what is the formula to dimension the vertical supports, knowing the
weight they'll have to carry?
Finn
You need to get another steel catalog. Many of them list I.
It depends on a lot of things like fillet radii and flange
taper.
What you need Finn is a Florida building code book. All that is spelled
out. There is dead load (weight of the structure) and live load
(the load you are going to put in the house expressed in pounds per square
foot).
In theory you don't know the dead load until you design the
house so you don't know the size of the beams until you know
how heavy they are :-) Chicken and egg. One must write a computer
program to iterate back and fourth until the error is small.
That's where the building codes comes in. They tell you what size
beams to use for how many stories you are going to put on your
house.
Paul Lamar
The AirCraft Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site. Copyright 1998-2002 All world wide rights reserved.
http://home.earthlink.net/~rotaryeng/ http://www.linux.org