<div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div class="gmail_quote"><div dir="ltr">On Sat, 27 Oct 2018 at 10:28, Greg Troxel <<a href="mailto:gdt@lexort.com">gdt@lexort.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>
So where I think we are is:<br>
<br>
there is almost zero support for the notion that guy wires or not is<br>
critical and therefore these must not be part of definitions. (Maybe<br>
just Graeme.)<br></blockquote><div><br></div><div>Sorry if I sound pedantic about it - I'm not an engineer of any sort, I'm just working off the definitions shown on the tower wiki page, & many other spots found by a mast v tower Google search eg</div><div><br></div><div><a href="https://en.wikipedia.org/wiki/Guyed_mast">https://en.wikipedia.org/wiki/Guyed_mast</a><br></div><div><br></div><div><span style="font-family:sans-serif;font-size:14px">A </span><b style="font-family:sans-serif;font-size:14px">guyed mast</b><span style="font-family:sans-serif;font-size:14px"> is a tall thin vertical </span><a href="https://en.wikipedia.org/wiki/Structure" title="Structure" style="text-decoration-line:none;color:rgb(11,0,128);background-image:none;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;font-family:sans-serif;font-size:14px">structure</a><span style="font-family:sans-serif;font-size:14px"> that depends on </span><a href="https://en.wikipedia.org/wiki/Guy-wire" title="Guy-wire" style="text-decoration-line:none;color:rgb(11,0,128);background-image:none;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;font-family:sans-serif;font-size:14px">guy lines</a><span style="font-family:sans-serif;font-size:14px"> for stability. The mast itself has the compressive strength to support its own weight, but does not have the shear strength to stand unsupported, and requires guy lines to resist lateral forces such as </span><a href="https://en.wikipedia.org/wiki/Wind_load" class="gmail-mw-redirect" title="Wind load" style="text-decoration-line:none;color:rgb(11,0,128);background-image:none;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;font-family:sans-serif;font-size:14px">wind loads</a><span style="font-family:sans-serif;font-size:14px"> and keep it upright</span> </div><div><br></div><div><a href="https://en.wikipedia.org/wiki/Radio_masts_and_towers">https://en.wikipedia.org/wiki/Radio_masts_and_towers</a></div><div><br></div><div><span style="font-family:sans-serif;font-size:14px">The terms "mast" and "tower" are often used interchangeably. However, in structural engineering terms, a tower is a self-supporting or </span><a href="https://en.wikipedia.org/wiki/Cantilever" title="Cantilever" style="background-image:none;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;text-decoration-line:none;color:rgb(11,0,128);font-family:sans-serif;font-size:14px">cantilevered</a><span style="font-family:sans-serif;font-size:14px"> structure, while a </span><a href="https://en.wikipedia.org/wiki/Guyed_mast" title="Guyed mast" style="background-image:none;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;text-decoration-line:none;color:rgb(11,0,128);font-family:sans-serif;font-size:14px">mast</a><span style="font-family:sans-serif;font-size:14px"> is held up by stays or </span><a href="https://en.wikipedia.org/wiki/Guy-wire" title="Guy-wire" style="background-image:none;background-position:initial;background-size:initial;background-repeat:initial;background-origin:initial;background-clip:initial;text-decoration-line:none;color:rgb(11,0,128);font-family:sans-serif;font-size:14px">guys</a><span style="font-family:sans-serif;font-size:14px">. Broadcast engineers in the UK use the same terminology.</span></div><div><br></div><div><a href="http://braziltowercompany.com/en/mast-or-tower.html">http://braziltowercompany.com/en/mast-or-tower.html</a></div><div><br></div><p style="margin:0px;padding:0px;border:0px;outline:0px;vertical-align:baseline;background:transparent;color:rgb(51,51,51);font-family:"Open Sans",Arial,sans-serif;font-size:16px">When discussing telecommunication antennas, the words “mast” and “tower” are often used interchangeably. However, structurally, they are not the same thing.</p><div><span style="background-color:transparent;color:rgb(51,51,51);font-family:"Open Sans",Arial,sans-serif;font-size:16px">A mast is an antenna held up by stays or guy-wires, while a tower is a self-supporting structure or is held up on one end only. Often, the term “tower” is used when the antenna is attached to the ground, while “mast” is used when the antenna is mounted onto another structure like a building or a tower.</span></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
There are really multiple sorts of things we are talking about:<br>
<br>
A) towers that are more than for antennas, like Tokyo, Killesberg,<br>
Eiffel, and other similar things that aren't really buildings but<br>
which have a significant purpose beyond holding an antenna up high<br>
<br>
B) things that support antennas that are big enough that a person --<br>
almost certainly a professional antenna repairer/installer or tower<br>
maintainer -- can climb up inside of, or stand on some top platform.<br>
Usually lattice or some sort of >1.5m diameter tube.<br>
<br>
C) things that support antennas that have lattice or foot platforms<br>
and can be climbed by people externally, sort of like a ladder, with<br>
a climbing harness, again only by trained people for repair/install.<br>
Like Rohn 65. Probably includes 30cm tubes that have climbing<br>
protrusions.<br>
<br>
D) things that support antennas that are small enough that no person<br>
can climb the outside. Ranging from 2cm diamater to maybe 20cm.<br>
<br>
In my usage<br>
A is a kind of tower<br>
<br>
B and C are "antenna tower" (separate from the A type tower) in the<br>
US. I gather in the UK B is tower and C is mast.<br>
<br>
D is a mast in the US<br>
<br>
I realize many here call A and B tower, and C and D mast.<br>
<br>
B and C are often different only in scale. For example, B coudl be<br>
triangular lattic that's 1.2m on a side, and C could be 0.5m on a side.<br>
Once you can climb inside, one you can't. But they are almost the same<br>
thing.<br>
<br>
Perhaps the C tubes/steps belong in D. It is arbitrary.<br>
<br>
With respect to guys, I would expect A and B to be almost never guyed,<br>
and C sometimes guyed (especially as it gets tall), sometimes not. D I<br>
would expect to be often short and not guyed, or taller and guyed.<br>
<br>
So how we want to group and label these is really arbitrary. But it<br>
would be good if we agree on the 4 groups of reality and then group<br>
them, and stop saying that guyed/not is critically important.<br></blockquote><div><br></div><div>OK, but can you translate all of that into a very simple one-line description that a non-engineer layman, looking at an aerial photo, can say Yep, I'll call this one a man_made=mast, but this one over here is a man_made=tower? :-)</div><div><br></div><div>Thanks</div><div><br></div><div>Graeme</div></div></div></div></div></div>