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Re: [TowerTalk] Climbing and working on Rohn 25g/45g towers -

To: "Richard Elizondo" <>, <>
Subject: Re: [TowerTalk] Climbing and working on Rohn 25g/45g towers -
From: "Bill Aycock" <>
Date: Mon, 24 Nov 2008 13:55:09 -0600
List-post: <">>
I  still consider that your post contains statements that are essentially 
meaningless, because they relate to loads in terms  that do not directly 
relate without more explanation and definition.

My career was as a Rocket motor designer, and , of necessity, included a 
working knowledge of material properties and how they relate to applied 
loads. My problem with your statements is that there is no meaning to the 
phrase "shear strength" without knowing how the loads are applied. The 
primary loads on a guyed tower are compressive and tensile; on an unguyed 
tower, bending becomes more important. In a tower, the applied loads are 
compression and tension, with shear being induced, not directly applied. The 
resistance to shear in a complex structure is different for different parts 
of the structure, and can not be determined if the point of force is not 
given, with respect to the geometry.

When a climber hangs on a tower, the total load is his weight, but the 
stresses are distributed differently if he is in line with a 'point' or a 
'face'; to determine factor of safety, one must know where he is. This is a 

At one point in your answer you claim that  you have just stated the facts. 
To be a useful fact, the statements you made need more clarification.  Where 
did the shear strength statement come from, and did it originally
come with a definition?


----- Original Message ----- 
From: "Richard Elizondo" <>
To: "Bill Aycock" <>; <>
Sent: Monday, November 24, 2008 11:24 AM
Subject: Re: [TowerTalk] Climbing and working on Rohn 25g/45g towers -

> The strength of the section is made up of its parts. If the section fails 
> to
> provide a 5000lbs anchor point, in no way will any of the welds, legs or
> lattice, provide it either.
> I am not stating the 25g tower is worthless. I actually quite fond of this
> tower and own several gin poles that are made of 25g, 45g and 55g 
> sections.
> What I have stated are just the facts. Like it or not, take it to heart, 
> or
> with a grain of salt.
> Ever wondered why Rohn used to make comments about climbers being less 
> than
> 250lbs in their field erection manuals ? (Hmmmm ...250lbs ...10-1 safety
> factor for positioning.... I must not know what I am talking about.)
> Seriously though however, I am open to discussion on what you see as
> erroneous in my post, since it is the same lecture given in all comtrain,
> belltech, and Radian fall protection classes.
> Richard
> ----- Original Message ----- 
> From: "Bill Aycock" <>
> To: "Richard Elizondo" <>; 
> <>
> Sent: Monday, November 24, 2008 8:31 AM
> Subject: Re: [TowerTalk] Climbing and working on Rohn 25g/45g towers -
>> This Whole post contains a major flaw that makes the real part 
>> irrelevant.
>> The statement about the strength of 25g is worthless, because the shear
>> strength is not define with respect to direction and method of loading,
>> and
>> is not related to the type of load applied by a falling body.
>> If the loading is cleared up, the rest might be germane.
>> Bill-W4BSG


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