I have a T beam web 6'-6"x3/8" thick, flange 31.5" x 3/4". The T beam
is 76'-6" long.Let me know if you can help to find the Section
Modulus.

thanks,

Ray

wrote in message
s.com...
I have a T beam web 6'-6"x3/8" thick, flange 31.5" x 3/4". The T beam
is 76'-6" long.Let me know if you can help to find the Section
Modulus.

thanks,

Ray


Break the cross section into two rectangles. Find the area of each and y, the distance
their centroids are from the bottom. Multiply the area of each by the y of each. Add those
up, then divide by the sum of the areas. That gives the centroid of the cross section.

Next, calculate the moments of inertia of each section, then use the parallel axis
transfer theorem to calculate their I at the centric of the cross section and add them up.

Now you can calculate the section modulus.

As I recall, that's how we did it in the old days, someone else will tell you the answer
from some computer program shortly!

"Rick" wrote in message ...

wrote in message
s.com...
I have a T beam web 6'-6"x3/8" thick, flange 31.5" x 3/4". The T beam
is 76'-6" long.Let me know if you can help to find the Section
Modulus.

thanks,

Ray


Break the cross section into two rectangles. Find the area of each and y, the distance
their centroids are from the bottom. Multiply the area of each by the y of each. Add
those
up, then divide by the sum of the areas. That gives the centroid of the cross section.

Next, calculate the moments of inertia of each section, then use the parallel axis
transfer theorem to calculate their I at the centroid of the cross section and add them
up.

Now you can calculate the section modulus.

As I recall, that's how we did it in the old days, someone else will tell you the answer
from some computer program shortly!

Must have been one hell of a dumpster you found THAT in!

http://www.efunda.com/math/areas/IndexArea.cfm

Suggest that you do the manual calculation also to verify that they agree.

David Merrill

wrote in message
s.com...
I have a T beam web 6'-6"x3/8" thick, flange 31.5" x 3/4". The T beam
is 76'-6" long.Let me know if you can help to find the Section
Modulus.

thanks,

Ray

On Oct 2, 10:16 am, "Rick" wrote:
wrote in message

s.com...

I have a T beam web 6'-6"x3/8" thick, flange 31.5" x 3/4". The T beam
is 76'-6" long.Let me know if you can help to find the Section
Modulus.

thanks,

Ray

Break the cross section into two rectangles. Find the area of each and y, the distance
their centroids are from the bottom. Multiply the area of each by the y of each. Add those
up, then divide by the sum of the areas. That gives the centroid of the cross section.

Next, calculate the moments of inertia of each section, then use the parallel axis
transfer theorem to calculate their I at the centric of the cross section and add them up.

Now you can calculate the section modulus.

As I recall, that's how we did it in the old days, someone else will tell you the answer
from some computer program shortly!

ANYBODY that knows of or has a proven subroutine to calculate the
section modulus of any reasonable cross section by spreadsheet, or
whatever, please let me know. I am sick and tired of doing this by
hand!!! A Tee section is tedious but straight forward; try an I-beam
section where each of the 4 flange legs is a different thickness!

Wolfgang

I highly recommend the program engineering power tools, at
http://www.pwr-tools.com/ Freeware version is very useful, and the full
version price is only $50. Has a section properties calculator where
you can draw arbitrary shapes, hollow or solid, and it will calculate
the moment of inertia and other properties. I checked a few geometries
by hand and they were fine. Also has a properties calculator for
several standard geometries, and I check them and found a bug, which the
author fixed quickly.

I drew this so that the base of the web was centered at (0,0), in
inches, so the top of the flange starts at (-15.75,78.75) and ends at
(15.75,78.75), and got these results:

Area 52.875
Xcg 0.00
Ycg 56.593
Ix 204440.
Iy 1953.83
Ixy 0.00
Ix0 35093.14
Iy0 1953.83
Ixy0 0.00
J 37046.98

Whe

Area - Total area (adjusted for any defined voids)
Xcg - Centroid of section (distance from X axis)
Ycg - Centroid of section (distance from Y axis)
Ix - Moment of inertia (about the X axis)
Iy - Moment of inertia (about the Y axis)
Ixy - Moment of inertia (about the XY axis)
Ixo - Moment of inertia (about centroidal X axis,
parallel with original X axis)
Iyo - Moment of inertia (about centroidal Y axis,
parallel with original X axis)
Ixyo - Moment of inertia (about centroidal XY axis)
Theta - Angle between the principal axis and the XY axis

Ix' - Moment of inertia (calculated at the specified
"Delta Angle from Principal Axis" )
Iy' - Moment of inertia (calculated at the specified
"Delta Angle from Principal Axis")
J - Polar moment of inertia about principal axis



Engineering Power Tools - Copyright 2002, Barry J. Opdahl

Hope this is useful.

--
Regards,
Carl Ijames carl dott ijames aat verizon dott net
(remove nospm or make the obvious changes before replying)

wrote in message
oups.com...
On Oct 2, 10:16 am, "Rick" wrote:
wrote in message

s.com...

I have a T beam web 6'-6"x3/8" thick, flange 31.5" x 3/4". The T
beam
is 76'-6" long.Let me know if you can help to find the Section
Modulus.

thanks,

Ray

Break the cross section into two rectangles. Find the area of each
and y, the distance
their centroids are from the bottom. Multiply the area of each by the
y of each. Add those
up, then divide by the sum of the areas. That gives the centroid of
the cross section.

Next, calculate the moments of inertia of each section, then use the
parallel axis
transfer theorem to calculate their I at the centric of the cross
section and add them up.

Now you can calculate the section modulus.

As I recall, that's how we did it in the old days, someone else will
tell you the answer
from some computer program shortly!

ANYBODY that knows of or has a proven subroutine to calculate the
section modulus of any reasonable cross section by spreadsheet, or
whatever, please let me know. I am sick and tired of doing this by
hand!!! A Tee section is tedious but straight forward; try an I-beam
section where each of the 4 flange legs is a different thickness!

Wolfgang

On Oct 2, 11:09 pm, "Carl Ijames"
wrote:
I highly recommend the program engineering power tools, athttp://www.pwr-tools.com/ Freeware version is very useful, and the full
version price is only $50. Has a section properties calculator where
you can draw arbitrary shapes, hollow or solid, and it will calculate
the moment of inertia and other properties. I checked a few geometries
by hand and they were fine. Also has a properties calculator for
several standard geometries, and I check them and found a bug, which the
author fixed quickly.

I drew this so that the base of the web was centered at (0,0), in
inches, so the top of the flange starts at (-15.75,78.75) and ends at
(15.75,78.75), and got these results:

Area 52.875
Xcg 0.00
Ycg 56.593
Ix 204440.
Iy 1953.83
Ixy 0.00
Ix0 35093.14
Iy0 1953.83
Ixy0 0.00
J 37046.98

Whe

Area - Total area (adjusted for any defined voids)
Xcg - Centroid of section (distance from X axis)
Ycg - Centroid of section (distance from Y axis)
Ix - Moment of inertia (about the X axis)
Iy - Moment of inertia (about the Y axis)
Ixy - Moment of inertia (about the XY axis)
Ixo - Moment of inertia (about centroidal X axis,
parallel with original X axis)
Iyo - Moment of inertia (about centroidal Y axis,
parallel with original X axis)
Ixyo - Moment of inertia (about centroidal XY axis)
Theta - Angle between the principal axis and the XY axis

Ix' - Moment of inertia (calculated at the specified
"Delta Angle from Principal Axis" )
Iy' - Moment of inertia (calculated at the specified
"Delta Angle from Principal Axis")
J - Polar moment of inertia about principal axis

Engineering Power Tools - Copyright 2002, Barry J. Opdahl

Hope this is useful.

--
Regards,
Carl Ijames carl dott ijames aat verizon dott net
(remove nospm or make the obvious changes before replying)

wrote in message

oups.com...

On Oct 2, 10:16 am, "Rick" wrote:
wrote in message

ups.com...

I have a T beam web 6'-6"x3/8" thick, flange 31.5" x 3/4". The T
beam
is 76'-6" long.Let me know if you can help to find the Section
Modulus.

thanks,

Ray

Break the cross section into two rectangles. Find the area of each
and y, the distance
their centroids are from the bottom. Multiply the area of each by the
y of each. Add those
up, then divide by the sum of the areas. That gives the centroid of
the cross section.

Next, calculate the moments of inertia of each section, then use the
parallel axis
transfer theorem to calculate their I at the centric of the cross
section and add them up.

Now you can calculate the section modulus.

As I recall, that's how we did it in the old days, someone else will
tell you the answer
from some computer program shortly!

ANYBODY that knows of or has a proven subroutine to calculate the
section modulus of any reasonable cross section by spreadsheet, or
whatever, please let me know. I am sick and tired of doing this by
hand!!! A Tee section is tedious but straight forward; try an I-beam
section where each of the 4 flange legs is a different thickness!

Wolfgang

Carl,

Thanks very much!

I shall check it out and try it.

Wolfgang

You can find a lot of section properties in the Corus Blue Book,
http://www.corusconstruction.com/en/...tees_from_ubs/


"David Merrill" wrote in message
news:XdxMi.114901$Xa3.551@attbi_s22...
http://www.efunda.com/math/areas/IndexArea.cfm

Suggest that you do the manual calculation also to verify that they agree.

David Merrill

wrote in message
s.com...
I have a T beam web 6'-6"x3/8" thick, flange 31.5" x 3/4". The T beam
is 76'-6" long.Let me know if you can help to find the Section
Modulus.

thanks,

Ray