[TowerTalk] AB105

Hardy Landskov n7rt at cox.net
Tue Apr 18 22:47:15 EDT 2006

Thanks for the specs. I have never have these numbers before. Mark asked me
if I had all the specs but I have about a dozen sheets that tell how to put
it together and that's it. 
However, I have started having some cross bracing failure problems. They
start at about the 70 ft level and go to the 85 ft point. All of the
failures are braces on the outside of the tower, not on the inside and are
all on one side. When I was up there, I thought my heart was going to stop.
There were four broken braces in a row up the tower on one ten foot section
and the tower section  had a bulge. Fortunately I had some of the G8A
stronger braces to fix the problem.  The tower is 140 ft with a 2el 80 mtr
beam and a 4el 40mtr. Probably way over loaded at 35 sq ft. wnd area.
Hardy N7RT

At 06:14 PM 4/18/06 -0400, donovanf at starpower.net wrote:
>I have a set of 20 year old AB-105 installation drawings 
>prepared for me and stamped by a P.E., but he died more than 
>10 years ago!   I'll be happy to send you a copy if that would 
>assist you.
>Penn-Tech International still manufactures AB-105 under their 
>commercial model number 2400. 
>Here's a transcription of the Penn-Tech Model 2400 (i.e., AB-
>105) Physical Properties.  They are probably of little value to 
>you, but would be essential for a P.E. who might prepare 
>drawings for you.
>Maximum practical height:  280 ft
>Max allowable bending moment at tower top:  20,000 ft-lbs
>Max vertical span between guys under max loading: 35 ft
>Weight of steel per lineal foot of tower height:  11.2 lbs
>Width of tower face between center of gravity of legs:  22.59 in
>Projected area of one face per lineal foot of tower:  0.5513 sq ft
>Wind pressure per lineal foot of tower:  27.99 lbs
>Radius of Gyration (least) of tower:  9.04 ins.
>Cross-sectional area of one leg:  0.603 sq in
>Moment of intertia (least) of tower:  147.76 in**4
>Distance from center of tower to center of gravity of leg: 13.04 
>Section modulus (least) of tower:  11.33 in**3
>Section modulus of one leg:  0.171 in**3 least
>Radius of gyration of one leg:  0.56 ins. least
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