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...

_ fired this volley in
:

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...


I don't have my blue manual handy, but unless that thing is a brake-
formed sheet metal beam, it'll probably handle the car, engine and
all. In that size, it's gotta run at least 11-lb per foot.

Your assignment is to get the beam mounted in such a way so that it
cannot twist _at_all_ when loaded. Probably the best way to do that
is to weld the ends to some substantially larger mounting plates onto
which A-frame legs would attach.

Get a trolley for that size beam, and you'd have a nice gantry crane.

LLoyd

On Wed, 18 Mar 2009 11:57:21 GMT, _
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 at least 3 standard wide-flange beams that fit that
description, running from 10 to 15 pounds per foot. It'd be
irresponsible to make a firm recommendation based on incomplete
information, but I think it's unlikely you'd have any problems lifting
a 4 cylinder engine with a W8x10 (the lightest of the standards) wide
flange beam spanning 13 feet as long as you use a little common sense.

--
Ned Simmons

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".

As Lloyd pointed out, mount that sucker so it absolutely positively
cannot turn on it's side or fall off of it's supports.

--
http://www.wescottdesign.com

On Wed, 18 Mar 2009 07:32:24 -0500, Lloyd E. Sponenburgh wrote:

_ fired this volley in
:

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...


I don't have my blue manual handy, but unless that thing is a brake-
formed sheet metal beam, it'll probably handle the car, engine and all.
In that size, it's gotta run at least 11-lb per foot.

Your assignment is to get the beam mounted in such a way so that it
cannot twist _at_all_ when loaded. Probably the best way to do that is
to weld the ends to some substantially larger mounting plates onto which
A-frame legs would attach.

Get a trolley for that size beam, and you'd have a nice gantry crane.

LLoyd

My father once arrived at a house fire driving the fire truck. The house
was located across a stream from the road, with an obviously owner-built
bridge between him and the house. So he set his right-seat guy out to
take a look to see if the bridge was sturdy enough.

"Wow! It's got 12 inch I-beams under there!"

Well, that's gotta be stout enough for ten fire trucks, right? So off he
goes, and in the middle of the stream the bridge sags badly. It's still
passable, but it's obviously ruined.

After the fire he goes and looks at the bridge. There are the 12" I-
beams -- on their sides, by design.

--
http://www.wescottdesign.com

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

not bend if I hook up a hoist to the centre and lift that motor?
Supported on the ends only...
....
Get a trolley for that size beam, and you'd have a nice gantry crane.

I have this exact beam in my garage. I have a trolley for it with a
one ton hand "rolling chain" hoist. Very handy.

Karl

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".

Machinery's Handbook.

Hope This Helps!
Rich

"Tim Wescott" wrote in message
...
On Wed, 18 Mar 2009 07:32:24 -0500, Lloyd E. Sponenburgh wrote:

_ fired this volley in
:

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...


I don't have my blue manual handy, but unless that thing is a brake-
formed sheet metal beam, it'll probably handle the car, engine and all.
In that size, it's gotta run at least 11-lb per foot.

Your assignment is to get the beam mounted in such a way so that it
cannot twist _at_all_ when loaded. Probably the best way to do that is
to weld the ends to some substantially larger mounting plates onto which
A-frame legs would attach.

Get a trolley for that size beam, and you'd have a nice gantry crane.

LLoyd

My father once arrived at a house fire driving the fire truck. The house
was located across a stream from the road, with an obviously owner-built
bridge between him and the house. So he set his right-seat guy out to
take a look to see if the bridge was sturdy enough.

"Wow! It's got 12 inch I-beams under there!"

Well, that's gotta be stout enough for ten fire trucks, right? So off he
goes, and in the middle of the stream the bridge sags badly. It's still
passable, but it's obviously ruined.

After the fire he goes and looks at the bridge. There are the 12" I-
beams -- on their sides, by design.

--
http://www.wescottdesign.com

There's one born every minute, Tim
Paul

_ 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...

I could be wrong but are rule of thumb in my head is a beam should only deflect 1" over
360" of lenght.

Made up beams must be constrained so they don't twist.

Stay inside that, life is good if I didn't blow it.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

On Mar 18, 7:02*pm, Wes wrote:
_ 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....

I could be wrong but are rule of thumb in my head is a beam should only deflect 1" over
360" of lenght. *

Made up beams must be constrained so they don't twist.

Stay inside that, life is good if I didn't blow it.

Wes

That rule is for beams supporting sheetrock walls, so they don't
crack. More deflection is allowed otherwise.

Wes wrote:
_ 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...

I could be wrong but are rule of thumb in my head is a beam should only deflect 1" over
360" of lenght.

Made up beams must be constrained so they don't twist.

Stay inside that, life is good if I didn't blow it.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller


My shop / hangar was made with 4" square pipe posts and 10" purlin
thirty feet long - unsupported. But I never hung much weight from them.

cavelamb fired this volley in
m:

My shop / hangar was made with 4" square pipe posts and 10" purlin
thirty feet long - unsupported. But I never hung much weight from
them.



Some time, look up the dead/live load capabilities of a 3-1/2" x 12"
lam-beam. You'd be amazed.

Consider, they use them to span garage door openings (supporting roof
structures) up to 22'.

LLoyd

"_" wrote in message
. ..
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...

Without knowing the exact flange width, thickness at the edge and web
thickness it's going to be a guess, but as someone else mentioned, on a 13'
span you are probably real safe.

I can affirm by experience that a 6" standard I-beam, 16' between concrete
walls, will support a 1300 pound welding machine in the center.

"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

"Elliot G" fired this volley in
m:

I can affirm by experience that a 6" standard I-beam, 16' between
concrete walls, will support a 1300 pound welding machine in the
center.



Extrapolate from this, if you can (I can't G). I know from having
built a press around one, that 8" x 8" beam with 3/8" web and 3/8"
flanges will take 27,000lb at the center of a 16" span, without any
_visible_ deflection. And that's on the flat (web vertical), rather
than with the bending moment on the flanges.

LLoyd

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

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"Elliot G" fired this volley in
m:

I can affirm by experience that a 6" standard I-beam, 16' between
concrete walls, will support a 1300 pound welding machine in the
center.



Extrapolate from this, if you can (I can't G). I know from having
built a press around one, that 8" x 8" beam with 3/8" web and 3/8"
flanges will take 27,000lb at the center of a 16" span, without any
_visible_ deflection. And that's on the flat (web vertical), rather
than with the bending moment on the flanges.

LLoyd

Me neither, I was just trying to offer a near comparison. A beam one size
smaller, 20% longer, and a known load.

But my WAG would be that his beam will FAIL at 7100, mine at 3300, and yours
at 210,000.

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


And that's a perfect example of the hazards of putting too much faith
in handbook tables. Look beyond Table 2 and you'll see a section
"Maximum Safe Load on Steel Beams." It deals with load reductions for
beams without lateral bracing, which is quite likely what the OP has
in mind. That's also one of the factors I alluded to that's in the
AISC charts, and it's easy to miss there as well unless you know to
look for it.

BTW, the deflection formula you gave is for a uniformly distributed
load, not a concentrated load like a hoist at the middle of a span
would apply. And in any case, the deflection isn't going to tell you
whether the beam is adequate to support a given load.

Was it Rumsfeld who said it's the stuff you don't know you don't know
that's the most worrisome?

--
Ned Simmons

"Elliot G" wrote in message
m...

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote in message
. 3.70...
"Elliot G" fired this volley in
m:

I can affirm by experience that a 6" standard I-beam, 16' between
concrete walls, will support a 1300 pound welding machine in the
center.



Extrapolate from this, if you can (I can't G). I know from having
built a press around one, that 8" x 8" beam with 3/8" web and 3/8"
flanges will take 27,000lb at the center of a 16" span, without any
_visible_ deflection. And that's on the flat (web vertical), rather
than with the bending moment on the flanges.

LLoyd

Me neither, I was just trying to offer a near comparison. A beam one size
smaller, 20% longer, and a known load.

But my WAG would be that his beam will FAIL at 7100, mine at 3300, and
yours at 210,000.






All I know is a 12" 20' I beam dropped 8 stories will cut a car in 1/2. My
dad in the 1950's was dismantling a build near the Port of Oakland and some
lady parked her new Buick right by the no parking construction zone sign.
My dad did not stop working as he was the owner of the company and was not
going to eat the cost for her stupidity. And the cable broke. Dad said was
funny as the police were there when the lady came back yelling screaming and
saying she was going to sue them. Cop asked lady to sign this paper. When
she asked what is was, he informed her it was a parking ticket. For parking
in a no parking zone. Dad did not have to pay for the car.

Rule of thumb is that for wood beams you do the deflection calc first,
then the strength calc since wood has a relatively low modulus of
elasticity. Steel is the opposite, you figure the strength first since
that is likely the limiting factor.


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

On Wed, 18 Mar 2009 19:49:44 -0500, Lloyd E. Sponenburgh wrote:

cavelamb fired this volley in
m:

My shop / hangar was made with 4" square pipe posts and 10" purlin
thirty feet long - unsupported. But I never hung much weight from
them.



Some time, look up the dead/live load capabilities of a 3-1/2" x 12"
lam-beam. You'd be amazed.

Consider, they use them to span garage door openings (supporting roof
structures) up to 22'.


The I-beam is $75.

I know sort-of about the laminated beams; put a pair of 'em in the kitchen
where someone had taken out a wall 40 years ago. The single 2x10 they put
in had sagged about 2" in the middle...didn't help that on one end it was
notched to about 3" height to sit on the top plate - not a stud; and one
the other about 1/2 inch was on a stud, that was all.

When I saw the state it was in one of the first things I did was tell the
teenager not to do any jumping on the floor in the room above - not that he
had, but he's a teenager, they're unpredictable.

_ fired this volley in
:

The I-beam is $75.


A 16-foot lam would cost a tad more -- well... a couple of tads G.

LLoyd

"Ned Simmons" wrote in message
...
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


And that's a perfect example of the hazards of putting too much faith
in handbook tables. Look beyond Table 2 and you'll see a section
"Maximum Safe Load on Steel Beams." It deals with load reductions for
beams without lateral bracing, which is quite likely what the OP has
in mind. That's also one of the factors I alluded to that's in the
AISC charts, and it's easy to miss there as well unless you know to
look for it.

BTW, the deflection formula you gave is for a uniformly distributed
load, not a concentrated load like a hoist at the middle of a span
would apply. And in any case, the deflection isn't going to tell you
whether the beam is adequate to support a given load.

Was it Rumsfeld who said it's the stuff you don't know you don't know
that's the most worrisome?

--
Ned Simmons

Oops! Ned you are right. I grabbed the wrong beam condition. BTW I
designed a sail boat trailer for a full keel sail boat using the deflections
as the limiting condition for obvious reasons. Also a spiral staircase, a
hydraulic engine hoist and a building addition, and a helicopter trailer
modification. As well as the deflection calcs for a 30' non standard I beam
with both distributed and concentrated loads. All had some safety factors
added and all have been in use for some time with no failures to perform.
With all that said, the table 4 on page 5-35 does have an easier to use
formula for safe loads. Given that the ends of the I beam are restricted
from rolling or departing from their location, I fail to see that using
deflection, and keeping it small, doesn't yield a safe condition. This
technique was used on the building addition, as well as the 30' non standard
I beam with the concurrance of a P.E.

Stu Fields

Well, I certainly hope you don't build things that I have to use with
your methods. I ran some calcs on standard 12" A36 steel I beams. Using
the published yield strength (the point where it bends and takes a set)
http://www.matweb.com/index.aspx search on A36

of 36,000 psi, I can get deflections in the 1/240 range. This is the
equivalent of NO factor of safety.

These calcs assume multiple beams that are cross braced and do not
include any derating to account for mid space twisting

Oops! Ned you are right. I grabbed the wrong beam condition. BTW I
designed a sail boat trailer for a full keel sail boat using the deflections
as the limiting condition for obvious reasons. Also a spiral staircase, a
hydraulic engine hoist and a building addition, and a helicopter trailer
modification. As well as the deflection calcs for a 30' non standard I beam
with both distributed and concentrated loads. All had some safety factors
added and all have been in use for some time with no failures to perform.
With all that said, the table 4 on page 5-35 does have an easier to use
formula for safe loads. Given that the ends of the I beam are restricted
from rolling or departing from their location, I fail to see that using
deflection, and keeping it small, doesn't yield a safe condition. This
technique was used on the building addition, as well as the 30' non standard
I beam with the concurrance of a P.E.

Stu Fields

On Thu, 19 Mar 2009 07:36:41 -0700, "Stuart Fields"
wrote:


Oops! Ned you are right. I grabbed the wrong beam condition. BTW I
designed a sail boat trailer for a full keel sail boat using the deflections
as the limiting condition for obvious reasons. Also a spiral staircase, a
hydraulic engine hoist and a building addition, and a helicopter trailer
modification. As well as the deflection calcs for a 30' non standard I beam
with both distributed and concentrated loads. All had some safety factors
added and all have been in use for some time with no failures to perform.
With all that said, the table 4 on page 5-35 does have an easier to use
formula for safe loads.

Is that titled "Approximate Safe Loads in Pounds on Steel Beams?" (I'm
looking at the 5th edition, which I suspect is older than yours.) Note
that this is an approximation, and uses a very conservative value for
allowable stress. It'd be interesting to compare results from that
table to the AISC code.

Given that the ends of the I beam are restricted
from rolling or departing from their location, I fail to see that using
deflection, and keeping it small, doesn't yield a safe condition.

Here's an example: Take the OP's 8" beam (let's assume it's a W8x13)
and set it up as a simply supported beam 5 feet long and apply a 12
ton point load at the middle. It'll deflect .090", which is less than
1/600 of the span, but the stress in the flanges will be over the
yield of A36 steel, and about 1.6 times the allowable stress.

Make the beam even shorter and you'll get to a point where shear
rather than bending stress is the limitation on loading.

This
technique was used on the building addition, as well as the 30' non standard
I beam with the concurrance of a P.E.

Quite often deflection *is* the controlling factor. Presumably your PE
evaluated the design and signed off on your deflection calculations as
appropriate in that instance. He might not have agreed if the beam was
unbraced or being used for overhead hoisting.

--
Ned Simmons

We have 4000 lb jib cranes with a 8"I beam as the boom. It was bolted to a mast and was supported at twelve feet. This beem had not measurable flex anywhere along its lenght.just make sure the load is lifted by tha bottom rail so not to roll

wrote in message
...
We have 4000 lb jib cranes with a 8"I beam as the boom. It was
bolted to a mast and was supported at twelve feet. This beem had not
measurable flex anywhere along its lenght.just make sure the load is
lifted by tha bottom rail so not to roll

Which 8" I or WF (WideFlange) beam?
http://www.saginawpipe.com/steel_i_beams.htm