Need pole advice from any engineering folks ............
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geneinmurphy
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next season I plan to build a new gourd rack (using PVC pipe gourds) that will use a 20' 1.90 OD 1.61 ID 6061 aluminum pole.......any idea as to how much weight this pole would support??? Thanks!!
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apundt-TX
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geneinmurphy
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apundt....nice link which compares different materials, but I can't figure out how to compute this into the load bearing capacity of my pole.....maybe someone else out here can assist.....
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apundt-TX
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60lbs according to Chuck's formulas
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geneinmurphy
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apundt.....thanks for the help!
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Guest
Gene,
I'm not a mechanical engineer, but I think I have a feel for what Chuck Abare wrote in the reference that Alton Pundt gave you. You asked how much weight the pole that you are planning on would support. This has so little relation to the forces that tend to make the pole fail that in Chuck's assumptions (to simplify his calculations), he assumes that the weight at the top of the pole is negligible.
The main forces that would tend to make the pole fail (blow over) are those produced by high winds. Chuck assumes that the force per unit area of some wind speed times the effective area of the house (or gourd rack in your case) is 20 lbs. This horizontal force at the top of poles of different heights and materials would make the poles deflect by the distances in Chuck's table.
To perfform a complete calculation, one would have to know the effective area for wind loading of the gourds, gourd arms, and pole. Then when a rigorous analysis is complete, an abitrary safety factor would be applied anyway.
Another approach might be to see what the specifications are for poles that commercial manufacturers use to support the sort of gourd rack that you are planning on.
Tony
I'm not a mechanical engineer, but I think I have a feel for what Chuck Abare wrote in the reference that Alton Pundt gave you. You asked how much weight the pole that you are planning on would support. This has so little relation to the forces that tend to make the pole fail that in Chuck's assumptions (to simplify his calculations), he assumes that the weight at the top of the pole is negligible.
The main forces that would tend to make the pole fail (blow over) are those produced by high winds. Chuck assumes that the force per unit area of some wind speed times the effective area of the house (or gourd rack in your case) is 20 lbs. This horizontal force at the top of poles of different heights and materials would make the poles deflect by the distances in Chuck's table.
To perfform a complete calculation, one would have to know the effective area for wind loading of the gourds, gourd arms, and pole. Then when a rigorous analysis is complete, an abitrary safety factor would be applied anyway.
Another approach might be to see what the specifications are for poles that commercial manufacturers use to support the sort of gourd rack that you are planning on.
Tony
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apundt-TX
- Posts: 986
- Joined: Thu Jan 22, 2004 7:34 pm
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2022-1 pair
1 pair 2021
2020- Didn't get setup fast enough in Pflugerville
2019- Apartment
2018 Divorce lost Colony in Dripping Springs
19 pair 2017
17 pair 2015
12 pair 2014
8 pair 2013
5 pair 2012
2 pair 2011
Tony,
I see what you are saying. "How much will it bend if a force (W) of 20 lbs, is applied horizontally to the very top of it."
I was thinking vertically here but it is a horizontal formula.
I see what you are saying. "How much will it bend if a force (W) of 20 lbs, is applied horizontally to the very top of it."
I was thinking vertically here but it is a horizontal formula.
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Guest
You guys are correct. Chuck's calculations let you know how much the ple will deflect when a force of 20 lb is applied. This gives you an idea how stiff the pole will be with a given weight at a given height and doesn't necessarily tell you the pole will break. If a pole did break, it wouldn't be from overloading. It would probably "work harden" from flexing in the wind, become brittle, and eventually snap after several years. The futher the pole flexes in the wind, the faster it will work harden. No one can predict exactly when it might/will fail. I would decide how much flex you are comfortable with (watching your box sway back and forth in the wind) and select the size and shape of the pole accordingly by playing with Chuck's numbers.