|
Posted by William Wixon on February 25, 2009, 11:29 am
Please log in for more thread options
>
>> daestrom,
>>
>> Excellent explanation!
>>
>> Basically, if tower weighs 500lbs and turbine weight 500lbs then there
>> is 1000lbs of static (or gravitational) force on the tower base.
>
> More that that! Don't forget the down thrust from the tension on the
> guy wires, (and I suppose, even the weight of the guy wires). If you
> insist on the guys being banjo-string tight, you could add thousands of
> pounds of stress.
>
> For my personal ham radio towers, I always went for a bit more sway, and
> a lot less guy tension. With the big communications towers that I managed
> at work, I listened to the engineers and insured the guy wires were tuned
> to the specified stress.
>
> Vaughn
>
apologies, not on-topic.. the this one totally amazed me when i first saw
it.
http://www.youtube.com/watch?v=udenD7RXGg0
"In April of 2001, in Mont-Carmel, Quebec,Canada, a small plane crashed into
a 1200 foot tower. The plane and its pilot remained wedged in the tower (the
pilot died on impact) and the tower was taken down one week later with
controlled explosions. This was the only way to get the plane down as the
tower was no longer stable due to the impact."
various other tower demolitions/collapses.
http://www.youtube.com/watch?v=z-sVm5hgiwU
http://www.youtube.com/watch?v=tKPr2SE2onQ
http://www.youtube.com/watch?v=JfZwJ3w3OL0
http://www.youtube.com/watch?v=tww3jF2NcdE
http://www.youtube.com/watch?v=plUud_Rsd80
|
|
Posted by vaughn on February 25, 2009, 4:00 pm
Please log in for more thread options
>
> "In April of 2001, in Mont-Carmel, Quebec,Canada, a small plane crashed
> into a 1200 foot tower. The plane and its pilot remained wedged in the
> tower (the pilot died on impact) and the tower was taken down one week
> later with controlled explosions. This was the only way to get the plane
> down as the tower was no longer stable due to the impact."
>
I have had two experiences with unstable guyed towers:
1) I was once hired to take an unstable tower down. Explosives were not an
option for various reasons, so we simply bought a thousand foot roll of guy
wire, and started our way up the tower replacing the guy wires with new
(from the bottom up, of course). Then we started our way back down
dismantling the tower. All ended well.
The next story does not end so well...
2) On my job I hired a professional tower company to remove a tower that I
had determined was unstable. The crew showed up and went to work. As I was
congratulating myself for hiring exactly the right folks to do this
dangerous job, they sent two men up the tower to start work. That kinda
surprised me. I wasn't about to climb that tower. 15 minutes later I heard
a terrible noise. Those two men rode the tower all the way down to the
tarmac (120 feet for the guy at the top) . It was a miracle that both
survived, but not without a whole lot of heartache in the hospital, in
rehab, and later in court.
Towers are a serious business.
Vaughn
|
|
Posted by Michael B on March 8, 2009, 11:25 am
Please log in for more thread options Distressingly enough, your comments are relatively on-topic.
What a shame that those towers were removed in a fashion
that caused them to be buckled and twisted. They could
have been the basis for a whole bunch of wind generator
towers.
> apologies, not on-topic.. =A0the this one totally amazed me when i first =
saw
> it.
>
> http://www.youtube.com/watch?v=3DudenD7RXGg0
>
> "In April of 2001, in Mont-Carmel, Quebec,Canada, a small plane crashed i=
nto
> a 1200 foot tower. The plane and its pilot remained wedged in the tower (=
the
> pilot died on impact) and the tower was taken down one week later with
> controlled explosions. This was the only way to get the plane down as the
> tower was no longer stable due to the impact."
>
> various other tower demolitions/collapses.
>
http://www.youtube.com/watch?v=3Dz-sVm5hgiwU
http://www.youtube.com/watch?v=3DtKPr2SE2onQ
http://www.youtube.com/watch?v=3DJfZwJ3w3OL0
http://www.youtube.com/watch?v=3Dtww3jF2NcdE
http://www.youtube.com/watch?v=3DplUud_Rsd80
|
|
Posted by Curbie on February 25, 2009, 3:19 pm
Please log in for more thread options Good points vaughn.
Initial tension on the guys and weight of the rigging.
How do they "tune" the pre or static (no horizontal loading) stress of
guys?
Do you know if 100% the above-anchor rigging-weight is transferred to
the base through the mast, or only a part of the weight because of guy
tension?
Thanks for the light.
Curbie
On Wed, 25 Feb 2009 14:33:39 GMT, "vaughn"
>
>> daestrom,
>>
>> Excellent explanation!
>>
>> Basically, if tower weighs 500lbs and turbine weight 500lbs then there
>> is 1000lbs of static (or gravitational) force on the tower base.
>
> More that that! Don't forget the down thrust from the tension on the guy
>wires, (and I suppose, even the weight of the guy wires). If you insist on
>the guys being banjo-string tight, you could add thousands of pounds of
>stress.
>
> For my personal ham radio towers, I always went for a bit more sway, and
>a lot less guy tension. With the big communications towers that I managed
>at work, I listened to the engineers and insured the guy wires were tuned to
>the specified stress.
>
>Vaughn
>
|
|
Posted by vaughn on February 25, 2009, 3:42 pm
Please log in for more thread options
> Good points vaughn.
>
> Initial tension on the guys and weight of the rigging.
>
> How do they "tune" the pre or static (no horizontal loading) stress of
> guys?
The professionals use dtrain guages to do the measuring & turnbuckles and/or
sliding preforms to do the adjusting.
>
> Do you know if 100% the above-anchor rigging-weight is transferred to
> the base through the mast, or only a part of the weight because of guy
> tension?
Is this a trick question? ;-)
Yes, on reflection I think all of the rigging weight gets transfered to the
base. Any wizards out there agree or disagree?
Vaughn
|
| Similar Threads | Posted | | Re: Calculating wind turbine tower loads | February 25, 2009, 12:54 pm |
| Re: Calculating wind turbine tower loads | February 25, 2009, 3:45 pm |
| Re: Calculating wind turbine tower loads | February 25, 2009, 3:52 pm |
| Re: Calculating wind turbine tower loads | March 2, 2009, 5:37 pm |
| Re: Calculating wind turbine tower loads | March 3, 2009, 4:43 am |
| Re: Calculating wind turbine tower loads | March 3, 2009, 10:30 am |
| Wind-Turbine Tower Forces | October 1, 2009, 5:09 pm |
| are you happy with your wind turbine? | January 18, 2007, 7:25 am |
| Looking at a gryphon wind turbine | October 18, 2007, 9:55 am |
| New (to me) type of wind turbine | May 12, 2007, 11:11 pm |
|
|
Yahoo! 
Google 
Windows Live 
del.icio.us 
digg 
Netscape 
XML Sitemap