[TowerTalk] Calculations

[Alan C. Zack]

OK, I agree with what you said.  But why can't a major manufacturer 
like UST provide these calcs when required and smaller guys like 
Tashjian Towers and Heights Towers can?

Jim Lux wrote:
> Probably because most building departments don't require IBC-2000 yet. Codes
> get revised every few years, but municipalities don't have to adopt them,
> and sometimes prefer to stay with the older code, since everyone is used to
> it.  For instance, Thousand Oaks, where I live, uses the California Building
> code, 2001 Edition, which is based on UBC97.  I would assume that most of
> California is the same. One should also bear in mind that folks doing a LOT
> of construction, or who have significant development plans might agitate for
> a change in codes in a locality to make their life easier. Since you're in
> the Las Vegas area, where there's a lot of new residential development, and
> some pretty significant resort/hotel development as well, maybe one of the
> developers likes the particular provisions of the other code, for what
> they're spending their millions of dollars on, and is willing to convince
> the city to go along.
> 
> It would probably cost a fair amount for the mfr (several thousand $,
> perhaps) to update all the calculations, etc., and unless a majority of
> their customers want it, they're not going to invest the dollars.  How many
> towers does the mfr sell in a year? How many of a particular model (because
> the calculations are model specific)?  Say they sell one tower of a given
> type a week (50 a year) at $2000 a crack, retail.  They actually only
> probably get $1500 or so wholesale for the tower, so they're making around
> $150 profit on each one.   Call it $7500 total profit on that model for a
> year.  Say it takes an engineer a week to do all the calculations. That's
> about $3000-$4000 (by the time you count the benefits, burden, taxes, etc.).
> It's just not worth it for the company to blow half their profit margin on a
> set of calculations that a small fraction of the customers need.  They'll
> figure that those folks who really need it will fork out the bucks needed to
> persuade their local building department.  As far as the retailer being able
> to get data where you can't, I would think it unlikely.  If the mfr has it,
> they'll supply it. If they don't, the retailer's probably not going to do
> any better than you, unless they can convince the mfr that they've got
> customers lined up to buy towers, if only the mfr had the calcs.
> 
> So, in summary, it's just the economics of the situation.  When it comes to
> building regulations, hams are an anomaly, with little incentive on
> anybody's part to make life easier (at least not for free).
> 
> Jim, W6RMK
> 
> 
> ----- Original Message -----
> From: "Alan C. Zack" <k7acz at cox.net>
> To: <WarrenWolff at aol.com>; <towertalk at contesting.com>
> Sent: Monday, September 13, 2004 7:53 PM
> Subject: Re: [TowerTalk] Calculations
> 
> 
> 
>>And why does a major tower manufacturer stick to outdated UBC-97 50
>>and 70 MPH wind calcs rather than the newer IBC-2000 specs.  UST did
>>send me a nice set of drawings based on UBC-97 that my Bldg Dept said
>>were great IF they were based on IBC-2000 instead.  I suppose some
>>hams will order and install the towers without a Bldg Permit or some
>>Bldg Depts still accept the UBC-97 specs, but why can't they provide
>>what the Bldg Dept requires?
>>Even my local AES store tried to get the IBC-2000 specs for me and
>>were also unsuccessful.
> 
> 
> 
> 

-- 
__________________________________________________________________________ 

Alan Zack
Amateur Radio Station K7ACZ
Las Vegas, Nevada, USA
Quality Engineer, The Boeing Company, Retired
Aviation Chief Warrant Officer, U.S. Coast Guard, Retired
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