[TowerTalk] Tower Collapse in South Dakota

[Steve Maki]

Sorry if this is a dupe, I'm having a problem posting to Towertalk today.

****************

Not always true. We regularly work on a 900' broadcast tower that is not 
on a pier pin. It's a Dresser-Ideco
built in the late 50's. I suspect that (from that era) it's not an outlier.

A tower can be engineered this way, but it's certainly not the most 
efficient way to do it material-wise.

-Steve K8LX


On 1/21/2023 11:43 AM, Rob Atkinson wrote:
 > Professionally constructed guyed lattice towers are always on pier
 > pins even if a base insulator isn't needed.  No commercial guyed tower
 > is ever put in the ham way of sinking the legs in concrete because the
 > tower has to be able to turn without twisting, because twisting will
 > cause a failure.  Hams seem to think that if their 100 foot R25 tower
 > loses its guys, it will stay vertical because the base is sunk in
 > concrete.  You can't treat a uniform cross section guyed tower as if
 > it is free standing.  The only reason hams get away with that business
 > of sinking the legs in concrete is that the majority of guyed ham
 > towers aren't very tall relative to face width and aren't heavily
 > loaded.  Any guyed tower hundreds of feet tall will _never_ be sunk in
 > concrete; they have to be on a pin or they won't survive.  The pin
 > likely helped the tower stay up at least at first, because the added
 > wind loading caused by ice added to the turning force.  If it had been
 > twisting with ice it would have collapsed a lot sooner.
 >
 > 73
 > Rob
 > K5UJ