Hello TowerTalkians: I need a favor from the list: I'm in the process of determing the capacity of and AB-105 tower for a building permit. I have a copy of the old TM for the AB-105 but the cross-sec
To all: Thanks to all who responded especially KK9A, K4XS and Frank ,W3LPL, who probably has forgotten more about this tower than I will ever learn. If I left some out of my list, I apologize, but wh
T'Talkers and Jim: Let's get some fundamentals out of the way first. In regards to design wind velocities: The IBC uses V3sec, Velocity of a 3 sec gust; the UBC uses the fastest mile wind velocity Vf
To the list: The IBC, both 2000 and 2003, and the UBC all refer to the TIA/EIA-222-F specification when they discuss the wind load and analysis of towers. The actual design criteria for towers can be
Alan: I find this interesting to say the least. The IBC never references the UBC it does reference the ASCE 7. In IBC 1609.1.1 which states that the wind loads are to be determined in accordance with
Bill,Jim,List and original poster: You are correct as you move the guys inward the vertical component of the guy force increases and the horizontal component decreases. This increases the vertical lo
Bill: The easiest way, if you bought it from a supplier is ask for a copy of the mill certification for the component. Sometimes the tubing is stamped or stenciled with the alloy demarcation on it. I
Hold on here: Just what does this thread have to do with Towers and the installation of amateur radio stations, especially when it drifts to political agendas of those posting?? Lets get back to the
Gary: I have engineered at least a 100 installations you are describing. Using a Steel W section or some Pipe or Structural tubing if sized correctly does not need to be back guyed. The UBC or IBC in
Sorry about the bandwidth. Mahlon I can't reply to your e-mail as your isp e-mail address bounces my reply. Please confim e-mail or add me to approved list if necessary. Thanks Hank / KR7X __________
That was a good thing to do. My standard specifications for concrete work requires that: Flat work - slabs and foundations can be stripped after 7 days of curing and loaded with component dead load o
I am really curious as to how this works. When I calculate the bending moment for a 40 foot section of 25G with a bracket at 8' up using TIA/EIA-222-F specifications for 130 mph design wind velocity,
Joe: Rohn 55g legs are 0.5203 sq in and 45g legs are 0.3043 sq in each. That is 71% larger, this is significant. Give the leg clear spacing (between the horizontals) and 50 ksi yield steel the allowa
Malcolm: If you notice the sections get larger as you go downward from the top. The tower sections get stronger and can handle more moment as you go downward. Just like the moment diagram for a canti
Blake: I beg to differ with you. Using TIA/EIA 222-F wind loading criteria and 70 mph wind velocity (min. recommended) a 40 foot section of Rohn, 25g un-guyed and cantilevered will develop a moment a
Well you are correct in that it is shown in the consumer catalog and the chart is dated 1987 and references 222-E. 222-F the latest standard differs from 222-E. I would not bet on a 40' 25g and ever
Pat: Actually the vertical load is indeed passed thru the cables and is transferred to the next lower section by the pulley connection to its top thru the stiffening band around the section. This dis
Since I was included by reference, here is my input. Steves' comment was for another installation where after using the appropriate stress allowable; I caclulated the load capacity of some A307(or A3
Laurent: I appreciate your problem. The best thing to do is to extend the concrete above ground so you can visually monitor the condition of the base concerning rust. I would leave the hole as it is.
Alan: Based on my experience your quote is not too far out of line. You have: 8 cy of concrete at $250/yd in place for $2000. 14 cy of excavation at $15 for $210 6 cy of backfill/compaction at $15 fo