[TowerTalk] Fwd: Achor bolts?

[jimlux]

On 3/24/18 11:39 AM, Hans Hammarquist via TowerTalk wrote:
> 
>   Jim,
> 
> So what you are telling me is that it would be OK to use the $3 anchor bolts for  freestanding tower?
> 
No, it's just that you can design something to use whatever components 
you want to use. Not every design needs A286 bolts that have been 
individually x-rayed for defects.

Regular old Grade 2 5/8" bolts from the bin at Home Depot might well be 
more than good enough, depending on the loads and the redundancy in the 
design.




> I guess I was overly pessimistic when I anchored my tower with 12 bolts into granite and added guy wires to it. My calculations show that it should withstand 130 mhp wind with 20 foot^2 on top. Could I take the guy wires off maybe? It would make it a lot easier to haul up antennas that way.
> 

130 mi/hr is about 40 lb/square foot, so that's a 800 pound lateral load 
at the top of your tower, plus whatever the load on the tower itself is.

What did the engineering calculations show? Most guyed towers (as in 
"designed to be guyed") have very weak base attachment (if any, beyond 
what's necessary to keep it from skidding), and can't take a lot of 
bending.  they take compression loads, and the guys take the lateral loads.

On the other hand, you're probably not going to be hauling antennas up 
in 100 mi/hr winds...
<grin>