[TowerTalk] Fall Zone

[Larry Banks]

Henry Petroski (a Civil Engineer and professor emeritus at Duke) is one of 
my favorite authors.  He has a column in the semi-monthly magazine American 
Scientist that is a must read for every engineer!  One of my favorite 
columns -- the story of the invention of the paper clip!

73 -- Larry -- W1DYJ



-----Original Message----- 
From: Wes
Sent: Monday, July 08, 2019 15:37
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Fall Zone

In 1963 the tower for KTHI-TV (now KVLY) was completed making it the tallest
structure in the world at 2063 feet.  I've been there and it is a sight to
behold. According to my GPS the guy anchors are over a 1/4 mile from the 
base of
the tower.  However the Tokyo Skytree is now the highest tower at 2080 feet 
and
it is free-standing in Earthquake land. Even though they have observation
platforms that can hold almost 3,000 people, I won't be one of them.

Roy Lewallen, W7EL, gave me a copy of Henry Petroski's book, "To Engineer is
Human", subtitled, "The Role of Failure in Successful Design" which has 
chapter
titles like, "Falling down is part of growing up" and "The ups and downs of
bridges."  If your neighbors are afraid of your tower falling on their 
property,
I don't blame them.

Wes  N7WS


On 7/8/2019 11:48 AM, Patrick Greenlee wrote:
> What was at one time the tallest man made structure in the world, a TV 
> tower at Caprock New Mexico, had available, at extra cost, de-icing 
> accessory equipment.  It was decided to forgo the extra expense and the 
> tower fell down during an ice storm that made the surrounding countryside 
> a federally proclaimed disaster area. This was the winter of 1960-1961. 
> The tower was 1610 ft tall.
>
> Overhead power distribution lines on wooden poles brought electricity to 
> the town of Tatum NM from the town of Lovington, 22 miles away. Most of 
> the 22 miles of poles were snapped off a few feet above ground.  Once a 
> wire on one side of a crossarm broke under the load of ice 4-6 inches in 
> diameter on the power wires it all came down like a row of dominoes. A 
> motorist observing the action said the poles snapped off one after another 
> with sounds like artillery fire.
>
> I walked to school the following morning and was the only person there 
> adult or child.
>
> Patrick        NJ5G
>
> On 7/8/2019 1:11 PM, Ron Baran wrote:
>> I think of a crank up tower with a DB18 atop as a work of kinetic art.  I 
>> can understand that others may not appreciate it but I'm hoping that no 
>> takes a saws-all to the base.  The maim issue with all towers is their 
>> safety.  I've seen lots of towers that were under guyed, over loaded with 
>> antennas and poorly maintained.  A municipality has every obligation to 
>> insist that a tower conform to wind loading requirements of all other 
>> structures in the jurisdiction.
>>
>> When you dropped the 200 foot guyed tower by severing one set of guys you 
>> turned it into a free standing tower with a large amount of force pulling 
>> it over.  Free standing towers, especially monopole towers, tend to fail 
>> at the base.  Way too much pressure on what is usually a set of bolts.
>>
>> I'm kind of interested in any engineering research into tower failures.
>>
>> I've seen photos of an earlier version of my tower that, indeed, failed 
>> between sections two and three of a four section tower. Severely 
>> overloaded when a squall showed up unannounced.
>>
>> Thanks for your comments Wilson.
>>
>> 73,
>>
>> Ron
>> W9XS
>>
>>
>> ________________________________
>> From: TowerTalk <towertalk-bounces at contesting.com> on behalf of Wilson 
>> Lamb <infomet at embarqmail.com>
>> Sent: Monday, July 8, 2019 10:20 AM
>> To: undefined
>> Subject: [TowerTalk] Fall Zone
>>
>> I wouldn't want a neighbor's tower/Yagi looming over my backyard...and I 
>> love towers!
>> The fall zone idea seems like simple good manners.
>>   I have been loosely involved in dropping 200' BC towers, dropped by 
>> cutting the rods at one guy anchor, thus losing all guys on that side.
>> They fell absolutely full length, with a few sections not even bent!
>> I think a foundation failure (soil, bolt, gin pole) would drop a crankup 
>> to full length.
>> Is there any experience available on this?
>> WL

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