Awl--

Been fooling around w/ this program/utility. Pretty neat.

Quick Qs:

For a W beam, you can orient it so that it looks like an "I" or like an "H".
Which orientation does the X-X value for the moment correspond to? I
believe X-X corresponds to the "I" orientation, judging from comparisons w/
channels, whose relative deflections is intuitively clear.

For a "4x13" W beam, whose flange width (4.060) is about equal to the main
web depth (4.160), and considerably thicker (flange thickness .345 vs web
thickness of .280), the program indicates deflection in the H position to be
*3 times* the deflection in the "I" position--about .311" vs. .106", for a
10 foot beam supported at the ends, w/ a 1000 lb point load at the center.

Does this make sense? I would have expected the deflection in the H
position to be only 1/2 the deflection in the I position.

Whazzup?
--
Mr. P.V.'d
formerly Droll Troll

"Proctologically Violated©®" wrote in message
...
Awl--

Been fooling around w/ this program/utility. Pretty neat.

Quick Qs:

For a W beam, you can orient it so that it looks like an "I" or like an
"H".
Which orientation does the X-X value for the moment correspond to? I
believe X-X corresponds to the "I" orientation, judging from comparisons
w/
channels, whose relative deflections is intuitively clear.

For a "4x13" W beam, whose flange width (4.060) is about equal to the main
web depth (4.160), and considerably thicker (flange thickness .345 vs web
thickness of .280), the program indicates deflection in the H position to
be
*3 times* the deflection in the "I" position--about .311" vs. .106", for a
10 foot beam supported at the ends, w/ a 1000 lb point load at the center.

Does this make sense? I would have expected the deflection in the H
position to be only 1/2 the deflection in the I position.

Whazzup?
--
Mr. P.V.'d
formerly Droll Troll




Without getting into a lot of "stuff" one would expect less deflection in
the "I" position. For the beam to deflect, the upper plate has to stretch
and the lower plate has to compress. This is the primary contributor to the
rigidity of the beam. The secondary contributor is the distributed
stretching and compression of the center web. In the "H" position, you only
have the distributed stretching and compression of the sides and the center
web contributes very little.

Jerry

Wide Flanged beams are designed so that they can carry maximum load with the
flanges top and bottom with the web between.
The objective is to locate the maximum amount of material at the
positions of maximum tension and compression. You don't need the material
concentrated at the center of the beam which is what you do when you arrange
a beam horizontally in an "H" position. The web is at the neutral axis.
A similar mistake in understanding occurs when people try to stiffen a
sheet steel wall with angle iron. They stitch it with the "V" against the
skin rather than with on leg of the "L" touching the skin and the other leg
as far away from the skin as possible to increase the moment arm.
Randy

"Proctologically Violated©®" wrote in message
...
Awl--

Been fooling around w/ this program/utility. Pretty neat.

Quick Qs:

For a W beam, you can orient it so that it looks like an "I" or like an "H".
Which orientation does the X-X value for the moment correspond to? I
believe X-X corresponds to the "I" orientation, judging from comparisons w/
channels, whose relative deflections is intuitively clear.

For a "4x13" W beam, whose flange width (4.060) is about equal to the main
web depth (4.160), and considerably thicker (flange thickness .345 vs web
thickness of .280), the program indicates deflection in the H position to be
*3 times* the deflection in the "I" position--about .311" vs. .106", for a
10 foot beam supported at the ends, w/ a 1000 lb point load at the center.

Does this make sense? I would have expected the deflection in the H
position to be only 1/2 the deflection in the I position.

Whazzup?
--
Mr. P.V.'d
formerly Droll Troll

Thank you for a very illuminating explanation!

I was thinking only in terms of rigidity of the one dimension, which I know
varies as the square. ie, a 2x8 is 4 times as stiff as a 2x4, etc.
Thus, I thought the H position of a beam would be "additively" stiffer than
the I position, in the case where the flanges were the same dimension as the
web.

But the compression/stretching aspect of the flanges is an eye-opener, and
makes a lot of sense!
Bless you!
I mighta gotten myself into a fair amount of trouble down the road, as in:
Damn, what are all those cracks doing in my new concrete floor--and why are
the beams sagging????
--
Mr. P.V.'d
formerly Droll Troll
"Jerry Foster" wrote in message
...

"Proctologically Violated©®" wrote in message
...
Awl--

Been fooling around w/ this program/utility. Pretty neat.

Quick Qs:

For a W beam, you can orient it so that it looks like an "I" or like an
"H".
Which orientation does the X-X value for the moment correspond to? I
believe X-X corresponds to the "I" orientation, judging from comparisons
w/
channels, whose relative deflections is intuitively clear.

For a "4x13" W beam, whose flange width (4.060) is about equal to the
main
web depth (4.160), and considerably thicker (flange thickness .345 vs web
thickness of .280), the program indicates deflection in the H position to
be
*3 times* the deflection in the "I" position--about .311" vs. .106", for
a
10 foot beam supported at the ends, w/ a 1000 lb point load at the
center.

Does this make sense? I would have expected the deflection in the H
position to be only 1/2 the deflection in the I position.

Whazzup?
--
Mr. P.V.'d
formerly Droll Troll




Without getting into a lot of "stuff" one would expect less deflection in
the "I" position. For the beam to deflect, the upper plate has to stretch
and the lower plate has to compress. This is the primary contributor to
the
rigidity of the beam. The secondary contributor is the distributed
stretching and compression of the center web. In the "H" position, you
only
have the distributed stretching and compression of the sides and the
center
web contributes very little.

Jerry

The scary thing about wide flange is that you can make a set-up that is
quite strong enough but downright scary when you see the amount of
deflection.
Stiffness is separate from strength.... almost. A real "eye opener"
is a stop action photo of a large aluminum airplane wing during rough
weather. The wing is certainly strong enough but flexes several feet up and
down at the wing tip. Often building codes provide a maximum deflection
value for floors when loaded simply because the occupiers would freak
otherwise. It is prudent to ask yourself if the structure you are building
has to be rigid or just strong. I was involved in building a free standing
jib crane for loading some type of heavy dies. The dies weighed around a
ton. The new crane was modified once then taken out and replaced simply
because the flex was not acceptable. We built a monster that I am sure
would fail at something like twenty times what its service load was.
The modern steel wide flange is a very efficient design. In the years I
have been fabricating structural I have seen total weights of buildings go
down yet the strength is still there. This is especially so when large
tubing started to appear for columns and bracing. It caught some
contractors by surprise who were bidding on the weight of steel rather than
the complexity of joints and type of members.
Randy

"Proctologically Violated©®" wrote in message
...
Thank you for a very illuminating explanation!

I was thinking only in terms of rigidity of the one dimension, which I know
varies as the square. ie, a 2x8 is 4 times as stiff as a 2x4, etc.
Thus, I thought the H position of a beam would be "additively" stiffer than
the I position, in the case where the flanges were the same dimension as the
web.

But the compression/stretching aspect of the flanges is an eye-opener, and
makes a lot of sense!
Bless you!
I mighta gotten myself into a fair amount of trouble down the road, as in:
Damn, what are all those cracks doing in my new concrete floor--and why are
the beams sagging????
--
Mr. P.V.'d
formerly Droll Troll
"Jerry Foster" wrote in message
...

"Proctologically Violated©®" wrote in message
...
Awl--

Been fooling around w/ this program/utility. Pretty neat.

Quick Qs:

For a W beam, you can orient it so that it looks like an "I" or like an
"H".
Which orientation does the X-X value for the moment correspond to? I
believe X-X corresponds to the "I" orientation, judging from comparisons
w/
channels, whose relative deflections is intuitively clear.

For a "4x13" W beam, whose flange width (4.060) is about equal to the
main
web depth (4.160), and considerably thicker (flange thickness .345 vs web
thickness of .280), the program indicates deflection in the H position to
be
*3 times* the deflection in the "I" position--about .311" vs. .106", for
a
10 foot beam supported at the ends, w/ a 1000 lb point load at the
center.

Does this make sense? I would have expected the deflection in the H
position to be only 1/2 the deflection in the I position.

Whazzup?
--
Mr. P.V.'d
formerly Droll Troll




Without getting into a lot of "stuff" one would expect less deflection in
the "I" position. For the beam to deflect, the upper plate has to stretch
and the lower plate has to compress. This is the primary contributor to
the
rigidity of the beam. The secondary contributor is the distributed
stretching and compression of the center web. In the "H" position, you
only
have the distributed stretching and compression of the sides and the
center
web contributes very little.

Jerry

R. Zimmerman wrote:

The scary thing about wide flange is that you can make a set-up that is
quite strong enough but downright scary when you see the amount of
deflection.
Stiffness is separate from strength.... almost. A real "eye opener"
is a stop action photo of a large aluminum airplane wing during rough
weather. The wing is certainly strong enough but flexes several feet up
and
down at the wing tip.

Just a comment, but the wings on the B-52 typically flex 15 feet at the
tips. Doesn't sound like much until you see marks on the wall at the
lowest and highest positions, with a B-52 wing clamped at the midpoint
position. Don't recall where I saw that particular exhibit, but it was
impressive.

I understand that the flexing of the wings alone is sufficient to serve as a
wing deicing system.

Often building codes provide a maximum deflection
value for floors when loaded simply because the occupiers would freak
otherwise. It is prudent to ask yourself if the structure you are
building
has to be rigid or just strong. I was involved in building a free
standing
jib crane for loading some type of heavy dies. The dies weighed around a
ton. The new crane was modified once then taken out and replaced simply
because the flex was not acceptable. We built a monster that I am sure
would fail at something like twenty times what its service load was.
The modern steel wide flange is a very efficient design. In the years
I
have been fabricating structural I have seen total weights of buildings go
down yet the strength is still there. This is especially so when large
tubing started to appear for columns and bracing. It caught some
contractors by surprise who were bidding on the weight of steel rather
than the complexity of joints and type of members.
Randy

"Proctologically Violated©®" wrote in message
...
Thank you for a very illuminating explanation!

I was thinking only in terms of rigidity of the one dimension, which I
know
varies as the square. ie, a 2x8 is 4 times as stiff as a 2x4, etc.
Thus, I thought the H position of a beam would be "additively" stiffer
than the I position, in the case where the flanges were the same dimension
as the web.

But the compression/stretching aspect of the flanges is an eye-opener, and
makes a lot of sense!
Bless you!
I mighta gotten myself into a fair amount of trouble down the road, as in:
Damn, what are all those cracks doing in my new concrete floor--and why
are
the beams sagging????
--
Mr. P.V.'d
formerly Droll Troll
"Jerry Foster" wrote in message
...

"Proctologically Violated©®" wrote in message
...
Awl--

Been fooling around w/ this program/utility. Pretty neat.

Quick Qs:

For a W beam, you can orient it so that it looks like an "I" or like an
"H".
Which orientation does the X-X value for the moment correspond to? I
believe X-X corresponds to the "I" orientation, judging from comparisons
w/
channels, whose relative deflections is intuitively clear.

For a "4x13" W beam, whose flange width (4.060) is about equal to the
main
web depth (4.160), and considerably thicker (flange thickness .345 vs
web thickness of .280), the program indicates deflection in the H
position to
be
*3 times* the deflection in the "I" position--about .311" vs. .106", for
a
10 foot beam supported at the ends, w/ a 1000 lb point load at the
center.

Does this make sense? I would have expected the deflection in the H
position to be only 1/2 the deflection in the I position.

Whazzup?
--
Mr. P.V.'d
formerly Droll Troll




Without getting into a lot of "stuff" one would expect less deflection in
the "I" position. For the beam to deflect, the upper plate has to
stretch
and the lower plate has to compress. This is the primary contributor to
the
rigidity of the beam. The secondary contributor is the distributed
stretching and compression of the center web. In the "H" position, you
only
have the distributed stretching and compression of the sides and the
center
web contributes very little.

Jerry



--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)