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About 11 am EST yesterday (Wed. 2/19/2003) the 1750 foot tower of WVAH-TV collapsed due to icing. There were no injuries. Transmitter building was crushed.

More at:

http://www.wchstv.com/...room/wv/news14.shtml

http://www.wvah.com/...om/shows/wed.shtml#2

RIP,
Gardner

edited to make links clicky

Damn,
they are falling all over the place recently.
In the same story they reported 1 other one falling.One in PORTSMOUTH, OHIO; 660 ft. Plus another is ready to topple from the ice they said.
Ice certainly is a bad thing on towers, especially when it begins to melt unevenly. We had a 2000ft tower go down in NC from ice in the early 1990's. At least with ice the towers have a fighting chance... we lost a 1750ft. one last year due to a plane colliding with it. Talk about massive destruction. I went and checked out the carnage after it went down, it was amazing seeing all that steel broken and twited. Video is amazing.
The classic line from a buddy of mine as we looked over the site... "I told you we shouldn't have put 4 on the elevator!!"
Oh how I miss her
Jason BASE 570

Seems to me it might not be a bad idea to put heating elements of some sort on antennas that are prone to icing.

Might prevent this kind of thing from happening in the future.

Is there any information/data available about how much stress various types of towers (wired and freestanders) can take? I know that I was very happy to get off a 450' freestander last week that felt like it was moving a lot with 3 people up top.

Ice storms really are just another form of Natural Disasters.

I was living in Ottawa, Canada in 97, an ice storm hit, took out enough power lines to knock out power to Ottawa, Montreal and parts of upstate NY. Parts of Montreal was without power for over 3 weeks, in the middle of February.

Steel structures that are build innexpensively (like antenas and high tension power corridors) are prime targets for destruction during ice storms. Unless a particularly nasty storm hits - like the one that took out central Canada in 97 - it's cheaper to build innexpensive structures and pay for the odd one that falls over then to build them all properly.

_Am

Yeah but it'll cost ya....

TIA/EIA-222 - Complete Document
Revision: F Chg: Date: 06/00/96
STRUCTURAL STANDARDS FOR STEEL ANTENNA TOWERS AND ANTENNA SUPPORTING STRUCTURES

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later,
Gardner
hey B... pm me. got plans tonight? I'll have my ballz - too bad weather looks like shit.

You remember the tower collapse in NC? dude, I used to live there and I remember seeing that in the news. Of course I was like ten at the time and I had no idea why I thought such tall structures were sooooo cool. Now I know

A big factor in the demise of towers is compression. See, a tower (guyed or freestanding) faces major compressional forces. The bottom needs to support all the weight on top. Most towers are deisgned to withstand 100 mph winds. So, essentially 3 people on top of a 450 foot freestanding tower adds little to the compressional bearings of the tower. Think of it this way---What percentage of weight are 3 people adding to a 450 foot steel structure? Not much. Maybe one hundredth of the weight of all the other metal used in construction.
This 1750 foot tower that fell because of an ice storm most likely failed because of the weight of the ice. A compression failure at the bottom. The metal buckles, and the top comes down. Like the world trade center incident. The bottom could not support the top once the weight overcame the load bearing capability. In the WTC, the heat weakend the metal, causing the top to start downward. The bottom could support a STATIC top, but not the force of the top falling down on the bottom.
Most towers are built very strong, and a human being or 3 climbing on them causes them little extra stress.
Think about the winds these towers face. And the guy wires are set to put compressional forces on the tower's base in high winds.
There is very little worry of winds. If winds were a problem, more towers would fall.
Engineers do know what they are doing, and the numbers they are crunching when designing these towers.
But, doulbe or triple the weight of the tower with say....ice, and it will come down. As witnessed.

I have talked with engineers about this. People on towers is a very little problem, and adds very little stress to the tower.

Later,
Thomas

That's not accurate about the WTC. It wasn't dynamic failure of the building of a floor but failure at each individual floor like dominoes. What you were describing would be more like one floor falling at the top and then the very bottom collapsing. One of the engineers in my office has a writeup on it. I'll grab his link.

Sorry. I wasn't very specific. I did not mean the TOP floor fell, and every subsequent floor fell. What I meant was there was a major failure around the heat source of burning jet fuel, and that is what caused the top section to come falling down. Not one floor at a time, but many floors all came crashing into the bottom section. Not the bottom floor, but the bottom section (below the burning part).
Your engineer most likely will say that heat caused failure, eh?
The building did not fall when the plane crashed into it. It fell after jet fuel burned and weakend (sp?) the structure.
And the part about the towers and structural integrity is correct.....I still believe. Like, even 10-12 people could climb a 450 foot freestander without problems.
Unless they all started rocking back and forth in "resonant frequency", which is a whole different topic.
Towers are strong and safe for the most part. I will say that some may be old and rusty, and thus unreliable for the safety aspect. The point is BASE jumping is not safe for the most part.
We all take our risks......you decide your own involvement.
Later,
Thomas