[TowerTalk] "I" beam question

[John Langdon]

The answer is: "it all depends".  Without actually calculating the tension in the guys and the loads on the anchors, there is no way to specify the materials you will need.  The loads are complex.  Not only do you need to know the I beam spec, but the proper size and orientation of the concrete base, how tall the I beam should be, the placement of the I beam within the concrete, the rebar within the concrete, and the type of concrete that should be used.

I am an electrical engineer, not a registered professional civil engineer. That is who you need. Your question is equivalent to: "What resistor should I use in my transceiver".  There is no general answer.  How much tower, what kind, how many guys, how far from the base, what antenna loads, what guy material, .... 

If you do not actually calculate your requirements, you would have to do massive "overkill" to be safe.  Use 50# per foot I beam in a pad 7' deep, 7' wide, and 7' long, with lots of rebar.  

Whoa!.  Too much!  Absolutely it is too much!  That's what the calculations do - tell you what is a reasonable specification to achieve your goals for the minimum amount of materials and labor.  That's why you should find someone to actually do the calculations.  Otherwise you will always be uncertain as to whether or not your installation will stay up, or whether you spent too much time and money on the anchors, or both.

I understand the urge to get out there and start digging, but this is a time for a little more contemplation. Decide in haste, repent at leisure.

73 John N5CQ

-----Original Message-----
From:	Rick Bullon [SMTP:kc5ajx@hotmail.com]
Sent:	Monday, October 12, 1998 9:47 PM
To:	towertalk@contesting.com
Subject:	[TowerTalk] "I" beam question


  OK I still need info on I beams for my elevated guys. I was told that 
there was a thread in the archives but I have gone though there till my 
eyes blurred.
 I went to the local metal yard today to see what they had. All of it is 
4 inches on the wide side of the beams with the difference in the 
distance between then they had 6,8,and 12 inches I figured that the 12x4 
inches stuff was to big so my question is is the 6x4 big enough or do I 
need the 8x4 inches beam?
 Another question is it is also lbs per foot the 6 in stuff is 12# per 
foot and the 8in is 13# per foot. is this the right stuff or am I 
looking at the wrong place.
  I.m getting desperate as I plan to start the digging and pouring next 
weekend when my vacation starts.
73
Rick
KC5AJX


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