Towertalk
[Top] [All Lists]

## [Towertalk] Tower Buidling 201

 To: [Towertalk] Tower Buidling 201 kr7x@attbi.com (Hank Lonberg) Mon, 2 Sep 2002 21:16:17 -0700
 ```Roger: I think you have it half right. The only time 1 guy will see all the lateral load is if the lateral load is in line with the guy direction. This holds true for a 3 guy, 4-guy, or 20-guy system. It is a matter of simple vector statics and the fact that guys are not rigid elements nor can they take compression loading. Guys are tension only elements and as soon as the line of force is not in line with the guy it is partially shared by another based on the vector statics and the angle of force on the guy system. Here I am talking in plan view or from above looking down on the system. As far as the distance from the base is concerned the closer the guy points are to the base of the tower the higher the actual tension will be. This can cause problems with the compressive strength of the tower section and the pull out strength of the guy anchor point. As to whether you use 4 or 3 or even 6 guys is a matter of land area available, anchor capacity and amount of torsion reduction desired in the completed tower system. Using 4 guys closer than 80% or 3 guys closer than 80% is not wrong you just have to calculate the forces in the guys, in the anchors and the tower to make sure everything is within allowable force ranges. N4KG is correct in saying that the maximum guy force will occur when the line of applied force is at 30 degrees to the guy direction in a 3 guy system and equates to 1.15 the amount that would be seen if it were in line with the guy direction. It is all a matter of vector mechanics and the concept of equilibrium of forces. On a couple of other notes: Galvanizing will not last indefinitely in a salt air environment, neither will aluminum. Stainless steel especially 304 will even rust in a marine environment. If you put ferrous metal no matter how protected in this environment maintenance of the coating will be required, period. The TIA/EIA 222 F standard is just that, a standard for the design of the towers not a regulation of the protective coating. I know of no building code in the US that prescribes protective coating requirements as part of any regulation or permit. The coating specifications are by the manufacturers or designers to give product or design life specifications for an item but are not regulations. The ASTM galvanizing specification was developed to give a standard of practice if one wants to utilize this particular standard. Nothing more nothing less. I hope this clears up this thread somewhat All the best 73 Hank Lonberg, S.E.,P.E. / KR7X Lonberg Design Group -----Original Message----- From: towertalk-admin@contesting.com [mailto:towertalk-admin@contesting.com] On Behalf Of Roger Borowski Sent: Monday, September 02, 2002 4:58 PM To: n4kg@juno.com; z-TowerTalk Subject: Re: [Towertalk] Tower Buidling 201 With 4 guys at 90 degrees apart there are only 4 degrees out of 360 degrees when one guy is holding the whole system up. With a 3 guy system at 120 degrees apart, there are 90 degrees out of 360 degrees when one guy has all the tension to support the whole system. This is the engineering reason for closer in spacing with a four guy system. The three guy system has each guy individually capable of providing for supporting the entire system 25% of the time the wind is blowing whereas the four guy system has each individual guy providing for support of the entire system less than 1% of the possible wind directions. All other than these 4 degrees out of 360 degrees there are two guys doing the wind load support work. This was quite an extensive tread about 4-5 years back and I guess some non-believers then still think its OK to use Rohn's guying standard for the fold over series of towers, which needed four guys to clear the backbone strut, on a conventional system using three guys. NOT! -=Rog-K9RB=- ----- Original Message ----- From: To: ; Sent: Monday, September 02, 2002 5:26 PM Subject: Re: [Towertalk] Tower Buidling 201 > Do you consider 15% to be a SIGNIFICANT increase in strength? > I don't. > > Worst case for a 3 way guy arrangement is at 30 degrees > to any one of the guys. Force in the guy is equal to the > in line force divided by COS 30 degrees (= 0.866) = 1.155 > or 15.5% more tenstion that an inline force which is the worst > case for 4 way guying. > > The old 80% guying guideline applied to the FULL rated height > of the towers (200 ft for R25). At 70 ft or less, the tower can take > more of the load from close in guys since it does NOT have to > support the weight, guy tension, and resolved wind load > of a tower extended to the full rated height. > > Tom N4KG > > On Mon, 2 Sep 2002 08:53:46 -0400 "Roger Borowski" > writes: > > > > ----- Original Message ----- > > From: > > To: > > Sent: Monday, September 02, 2002 3:01 AM > > Subject: Re: [Towertalk] Tower Buidling 201 > > > > > > > > > > Note that for tower heights under 70 ft, Rohn shows a 35 ft (50%) > > > guying radius for their (discontinued) fold over tower > > intallations. > > > > > > Tom N4KG > > > > > That is because the fold over series must be guyed with FOUR guys, > > 90 degrees > > apart, which is a significantly stronger method of guying vs. three > > guys at 120 > > degrees apart. There was a tread about this about 4-5 years ago. > > 73, -=Rog-K9RB=- > > > > > ________________________________________________________________ > GET INTERNET ACCESS FROM JUNO! > Juno offers FREE or PREMIUM Internet access for less! > Join Juno today! For your FREE software, visit: > http://dl.www.juno.com/get/web/. > _______________________________________________ > Self Supporting Towers, Wireless Weather Stations, see web site: http://www.mscomputer.com > Call 888-333-9041 to place your order, mention you saw this ad and take an additional 5 percent off > any weather station price. > _______________________________________________ > Towertalk mailing list > Towertalk@contesting.com > http://lists.contesting.com/mailman/listinfo/towertalk > _______________________________________________ Self Supporting Towers, Wireless Weather Stations, see web site: http://www.mscomputer.com Call 888-333-9041 to place your order, mention you saw this ad and take an additional 5 percent off any weather station price. _______________________________________________ Towertalk mailing list Towertalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
 Current Thread Re: [Towertalk] Tower Buidling 201, Stan & Patricia Griffiths [Towertalk] Tower Buidling 201, K7LXC@aol.com [Towertalk] Tower Buidling 201, n4kg@juno.com [Towertalk] Tower Buidling 201, n4kg@juno.com [Towertalk] Tower Buidling 201,