Thicker steel usually means stronger so therefore the difference in specs. If
you want to see if 45 will do a better job if guyed heavier then you need to
get a structural engineer involved. Always follow the manufacturer's
specifications unless you have someone else qualified involved to vary from
them. Phil KB9CRY
-------------- Original message --------------
> OK, here's a toss up that should generate some real discussion:
> Rohn 45 and Rohn 55 have essentially the same face width and
> the same cross bracing. The Rohn 55 has slightly thicker wall
> side rails -- the center to center spacing of the side rails
> is only 1/4" more (about 1.5% larger) than that of Rohn 45.
> I am confused when comparing the Rohn 45 and 55 catalog specs
> for 100' at 110 MPH. The 45 design uses 1/4" EHS at the top and
> 3/16" for the intermediate guys ... it is rated for 7.9 sq. ft.
> The 55 design uses 5/16" EHS at the top, 1/4" EHS in the middle
> and 3/16" EHS at the bottom ... it is rated for 15 sq. ft. The
> guy anchors for the 55 design have about 25% more concrete (.84
> cu yd vs. .67 cu yd).
> I can't imagine the difference in rated capacity is explained by
> the modestly larger side rails. Does this indicate that Rohn 45
> could safely be loaded more heavily if the guy wires were upgraded
> (e.g., to the Rohn 55 design or by using TA45 "star" guy brackets
> and double guys at each level)? I also know that many users have
> significantly overloaded towers when compared to Rohn's catalog
> designs and gotten away with it.
> Is the added cost (about 25%) for Rohn 55 "worthwhile" -- is it
> really that much stronger or is Rohn 45 "as good" when guyed the
> same way as 55?
> ... Joe, K4IK
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
> Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
> and ask for Sherman, W2FLA.
> TowerTalk mailing list
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
TowerTalk mailing list