[450] K1FSY Mast Strength Analysis
John Foege
john.foege at gmail.com
Fri Nov 15 04:34:34 EST 2013
Results below also attached as *.TXT file for better formatting/readability.
Analysis of Antenna Mast Strength
----------------------------------
Produced for: K1FSY
Performed by: W1QEX
Date: 11/15/2013
All calculations assume:
* Single M2-9SSB antenna with 1.2 ft^2 cross sectional wind loading area is
at top of mast
* 1-1/4 Trade Size EMT (1.51 in. OD / 0.065 in. nominal wall thickness)
* 36,000 PSI elastic yield strength / 58,000 absolute tensile strength
(standard EMT conduit)
* Antenna is broadsided into the wind for maximum wind contact surface area
* All wind speeds are rounded to the nearest whole mph value
* Point of failure is at thrust bearing / top of tower and mast interface
Case #1
-------
* Mast protrudes 20' above thrust bearing
Results:
Bending stress of 35,908 psi occurs @ 45 mph wind speed. Wind speeds in
excess of
45 mph will exceed the elastic yield strength of EMT conduit, resulting in
an irreversible
bending of the mast.
Bending stress of 57,612 psi occurs @ 57 mph wind speed. Wind speed in
excess of 57 mph
will exceed the absolute tensile strength of EMT conduit, resulting in
breaking of the mast.
Case #2
-------
* Mast protrudes 17' above thrust bearing
Results:
Bending stress of 36,194 psi occurs @ 51 mph wind speed. Wind speeds in
excess of
51 mph will exceed the elastic yield strength of EMT conduit, resulting in
an irreversible
bending of the mast.
Bending stress of 58,792 psi occurs @ 65 mph wind speed. Wind speed in
excess of 65 mph
will exceed the absolute tensile strength of EMT conduit, resulting in
breaking of the mast.
Case #3
-------
* Mast protrudes 15' above thrust bearing
Results:
Bending stress of 36,369 psi occurs @ 56 mph wind speed. Wind speeds in
excess of
56 mph will exceed the elastic yield strength of EMT conduit, resulting in
an irreversible
bending of the mast.
Bending stress of 58,462 psi occurs @ 71 mph wind speed. Wind speed in
excess of 71 mph
will exceed the absolute tensile strength of EMT conduit, resulting in
breaking of the mast.
Case #4
-------
* Mast protrudes 10' above thrust bearing
Results:
Bending stress of 36,125 psi occurs @ 74 mph wind speed. Wind speeds in
excess of
74 mph will exceed the elastic yield strength of EMT conduit, resulting in
an irreversible
bending of the mast.
Bending stress of 58,4291 psi occurs @ 94 mph wind speed. Wind speed in
excess of 94 mph
will exceed the absolute tensile strength of EMT conduit, resulting in
breaking of the mast.
73s de W1QEX
John
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.vhfwiki.com/pipermail/450/attachments/20131115/6034bdf8/attachment.html>
-------------- next part --------------
Analysis of Antenna Mast Strength
----------------------------------
Produced for: K1FSY
Performed by: W1QEX
Date: 11/15/2013
All calculations assume:
* Single M2-9SSB antenna with 1.2 ft^2 cross sectional wind loading area is at top of mast
* 1-1/4 Trade Size EMT (1.51 in. OD / 0.065 in. nominal wall thickness)
* 36,000 PSI elastic yield strength / 58,000 absolute tensile strength (standard EMT conduit)
* Antenna is broadsided into the wind for maximum wind contact surface area
* All wind speeds are rounded to the nearest whole mph value
* Point of failure is at thrust bearing / top of tower and mast interface
Case #1
-------
* Mast protrudes 20' above thrust bearing
Results:
Bending stress of 35,908 psi occurs @ 45 mph wind speed. Wind speeds in excess of
45 mph will exceed the elastic yield strength of EMT conduit, resulting in an irreversible
bending of the mast.
Bending stress of 57,612 psi occurs @ 57 mph wind speed. Wind speed in excess of 57 mph
will exceed the absolute tensile strength of EMT conduit, resulting in breaking of the mast.
Case #2
-------
* Mast protrudes 17' above thrust bearing
Results:
Bending stress of 36,194 psi occurs @ 51 mph wind speed. Wind speeds in excess of
51 mph will exceed the elastic yield strength of EMT conduit, resulting in an irreversible
bending of the mast.
Bending stress of 58,792 psi occurs @ 65 mph wind speed. Wind speed in excess of 65 mph
will exceed the absolute tensile strength of EMT conduit, resulting in breaking of the mast.
Case #3
-------
* Mast protrudes 15' above thrust bearing
Results:
Bending stress of 36,369 psi occurs @ 56 mph wind speed. Wind speeds in excess of
56 mph will exceed the elastic yield strength of EMT conduit, resulting in an irreversible
bending of the mast.
Bending stress of 58,462 psi occurs @ 71 mph wind speed. Wind speed in excess of 71 mph
will exceed the absolute tensile strength of EMT conduit, resulting in breaking of the mast.
Case #4
-------
* Mast protrudes 10' above thrust bearing
Results:
Bending stress of 36,125 psi occurs @ 74 mph wind speed. Wind speeds in excess of
74 mph will exceed the elastic yield strength of EMT conduit, resulting in an irreversible
bending of the mast.
Bending stress of 58,4291 psi occurs @ 94 mph wind speed. Wind speed in excess of 94 mph
will exceed the absolute tensile strength of EMT conduit, resulting in breaking of the mast.
-------------- next part --------------
_______________________________________________
450 mailing list
450 at lists.vhfwiki.com
http://lists.vhfwiki.com/cgi-bin/mailman/listinfo/450
More information about the 450
mailing list