Re: [TowerTalk] misaligned vertical towers

[Grant Saviers <grants2@pacbell.net>]

Another take away from K7NV's analysis is how there is significantly 
less stress in a pier pin base tower to tilt than the usual tower 
section in concrete.  Perhaps it is more important to follow the tilt of 
an embedded section rather than stress the near to bottom sections by 
making the rest of the tower plumb with the guys.  That is staying in 
column (straight) with the embedded or first freestanding section.  As 
his analysis shows it doesn't take much sway before the tower is 
overloaded at or near the base with an embedded section base. 
http://k7nv.com/notebook/towerstudy/towerstudy1.html
Your tension meter guy setup should prevail as it insures there are no 
forces bending the tower in the static (no wind forces) situation.  If 
unequal guy tensions are applied to make a tilting tower plumb then 
there are built in unequal leg stresses which if the wind load is from 
the wrong direction might overload the tower. On even a 1 degree tilted 
tower, the asymmetrical guy loads from the tower weight probably won't 
be measurable on a Loos gauge.  Bottom line IMO - adjust guys to stay in 
column and have equal guy tensions and if there is a little tilt declare 
it a propagation advantage.
Grant KZ1W


On 3/22/2013 6:36 AM, Jim Lux wrote:
> On 3/21/13 1:00 PM, Steve K7AWB wrote:
> > I have two towers up.  A 90 foot Rohn 45 with a 6-el 20 meter beam on it
> > and
> > a 102 foot Rohn 25 without anything on it yet.  Both are guyed. In 
> > putting
> > them up, a group of us used a Loos tension meter and our eyesight at the
> > bottom of each tower to make them vertical.
> >
> > But when I look and align the two towers next to each other by walking
> > around until they are "next" to
> > each other, one or both are off vertically with respect to each other.
> >
> > How do I figure which is straight and which is off or maybe both are
> > slight off?
> > I really don't want to climb them now in the bad weather and drop a 
> > plumb
> > bob and do not have a survey level.  They are really 135 feet apart.
>
> How far off from vertical are they?  You might not care.   A foot at 
> 90 feet is less than a degree. The loads won't be appreciably different.
> K7NV's website (http://k7nv.com/notebook/towerstudy/towerstudy1.html) 
> shows displacements of more than a foot on a 100 ft Rohn45 tower in a 
> 90 mi/hr wind.  with aramid guys, displacements were more than 4 feet..
>
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