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Posted by Proctologically Violated©® on November 18, 2006, 4:10 pm
Awl,
(See the original thread on alt.machines.cnc, where Elson dissed me and I
thusly started the usual web-bristling, w/ the usual huff, puff, and
attendant dance. But really, he shouldna dissed me, man, shouldna dissed
me....)
But moving onwerd and forwerd:
Even tho I had it on good authority that no goddamm builder on earth uses
the earth's
curvature ceptin builders of long-assed bridges, the image of oh-so slowly
diverging radii
of the earth did bring this to mind:
For a tall building building to be "truly plumb", *each wall* would have to
be plumb, ie, lie exactly along the *line of the earth's radius*, from the
point where sed wall touches the ground.
*Necessarily*, then, the walls of a tall building must **diverge**, just as
the earth's radii diverge, from the earth's center to the base of the
building.
Rough calcs indicate that a 1500 ft tall building, w/ a 400' x 400' base,
would have its top floor about 1/2" longer on an edge than the ground floor.
(!!!)
Iow, a "properly" constructed building will be a very long truncated
pyramid, point-side down, base up.
If a skyscraper is constructed w/ strictly parallel walls, as far as gravity
is concerned there is actually a tipping "moment", sorta like the Leaning
Tower of Pizza.
Not significant, of course, but hey, 1/2" is 1/2".
Which gives the top floor an area of 160,400 sq ft, vs the ground floor's
160,000 sq ft.
Which is, hey, but another lawyer's/stockbroker's office, which is, hey, but
even mo' rent.
Or, inversely/conversely/obversely/reversely/obtusely,
A tall building might have to be built pyramidally, *narrow end up*, to
*counteract* the slight tipping moment of one (or both) of the walls not
lying strictly in line w/ the earth's radii.
Uh oh, there goes the lawyer's office....
I can see Elson now, w/ his gadget at the Sears tower....
--
------
Mr. P.V.'d (formerly Droll Troll), Yonkers, NY
Stop Corruption in Congress & Send the Ultimate Message:
Absolutely Vote, but NOT for a Democrat or a Republican.
Ending Corruption in Congress is the *Single Best Way*
to Materially Improve Your Family's Life.
The Solution is so simple--and inexpensive!
entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie,
all d'numbuhs
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Posted by Jeff R. on November 18, 2006, 4:46 pm
>... For a tall building building to be "truly plumb", *each wall* would
>have to
> be plumb, ie, lie exactly along the *line of the earth's radius*, from the
> point where sed wall touches the ground.
>
> *Necessarily*, then, the walls of a tall building must **diverge**, just
> as
> the earth's radii diverge, from the earth's center to the base of the
> building.
>
> Rough calcs indicate that a 1500 ft tall building, w/ a 400' x 400' base,
> would have its top floor about 1/2" longer on an edge than the ground
> floor.
> (!!!)
> Iow, a "properly" constructed building will be a very long truncated
> pyramid, point-side down, base up.
1/2" on an Empire-State-sized building? I trust your calcs, but do you
really think there are builders working at that scale to *that* accuracy?
(Other than just interesting "measuring" exercises, that is)
Interesting concept, (I've often pondered it myself), but swallowed up
entirely in the tolerance (or margin for error).
You could argue, f'r'instance, that any one "vertical" strut would indeed
have the earth-centre-pointing vector contained entirely within itself,
unless it was considerably less than 1/2" thick.
--
Jeff R.
(pass me another beer)
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Posted by Proctologically Violated©® on November 18, 2006, 4:50 pm
You're preaching to the choir here. :)
Read the claims in the original thread. goodgawd....
1/2" is positively *gargantuan* compared to the other stuff. :)
--
------
Mr. P.V.'d (formerly Droll Troll), Yonkers, NY
Stop Corruption in Congress & Send the Ultimate Message:
Absolutely Vote, but NOT for a Democrat or a Republican.
Ending Corruption in Congress is the *Single Best Way*
to Materially Improve Your Family's Life.
The Solution is so simple--and inexpensive!
entropic3.14decay at optonline2.718 dot net; remove pi and e to reply--ie,
all d'numbuhs
>
>>... For a tall building building to be "truly plumb", *each wall* would
>>have to
>> be plumb, ie, lie exactly along the *line of the earth's radius*, from
>> the
>> point where sed wall touches the ground.
>>
>> *Necessarily*, then, the walls of a tall building must **diverge**, just
>> as
>> the earth's radii diverge, from the earth's center to the base of the
>> building.
>>
>> Rough calcs indicate that a 1500 ft tall building, w/ a 400' x 400' base,
>> would have its top floor about 1/2" longer on an edge than the ground
>> floor.
>> (!!!)
>> Iow, a "properly" constructed building will be a very long truncated
>> pyramid, point-side down, base up.
>
>
> 1/2" on an Empire-State-sized building? I trust your calcs, but do you
> really think there are builders working at that scale to *that* accuracy?
> (Other than just interesting "measuring" exercises, that is)
>
> Interesting concept, (I've often pondered it myself), but swallowed up
> entirely in the tolerance (or margin for error).
>
> You could argue, f'r'instance, that any one "vertical" strut would indeed
> have the earth-centre-pointing vector contained entirely within itself,
> unless it was considerably less than 1/2" thick.
>
> --
> Jeff R.
> (pass me another beer)
>
>
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Posted by Don Klipstein on November 19, 2006, 10:57 pm
>
>>... For a tall building building to be "truly plumb", *each wall* would
>>have to
>> be plumb, ie, lie exactly along the *line of the earth's radius*, from the
>> point where sed wall touches the ground.
>>
>> *Necessarily*, then, the walls of a tall building must **diverge**, just
>> as
>> the earth's radii diverge, from the earth's center to the base of the
>> building.
>>
>> Rough calcs indicate that a 1500 ft tall building, w/ a 400' x 400' base,
>> would have its top floor about 1/2" longer on an edge than the ground
>> floor.
>> (!!!)
>> Iow, a "properly" constructed building will be a very long truncated
>> pyramid, point-side down, base up.
>
>
>1/2" on an Empire-State-sized building? I trust your calcs, but do you
>really think there are builders working at that scale to *that* accuracy?
>(Other than just interesting "measuring" exercises, that is)
>
>Interesting concept, (I've often pondered it myself), but swallowed up
>entirely in the tolerance (or margin for error).
>
>You could argue, f'r'instance, that any one "vertical" strut would indeed
>have the earth-centre-pointing vector contained entirely within itself,
>unless it was considerably less than 1/2" thick.
>
>--
>Jeff R.
>(pass me another beer)
I would say that buildings where this comes into play need to be
tolerant of all of this $#!+. Something as tall as a WTC tower and twice
as wide needing to be 1/2 inch wider at the top than the bottom - it
better not be so touchy as to easily topple if it ain't!
Just consider wind problems! NYC can expect to get hit by a hurricane
badly enough to get peak gusts around 90-100 MPH at "treetop level" at
least once per century. Expect that to translate to about 110 MPH on the
top half of a building that tall - even though hurricanes have their worst
winds in lower parts of the atmosphere! 110 MPH of 74 F air at barometric
pressure 28 inches works out to 27.9 pounds per square foot of
wind-hit side area assuming drag coefficient 1 if I calculated right!
The building's base would have stress a few times that of tension on the
upwind side and similar compression stress on the downwind side! In terms
of force per building footprint area, multiplied by reciprocal of fraction
of the building footprint that has structural members that withstand this
force.
Hurricanes ain't the only problem! Consider the Nor'easters of March
1932, March 1962, March 1984, October 1991, December 1992 and March 1993!
Boston might also complain about a February 1978 storm and one in
early 2005! Along with Nor'easters being worse 1,000 feet up than
tropical storms with same treetop level winds are! As for Midwest - how
about Ohio-Indiana around January 25 1978?
Also consider the downburst, microburst, gustnado and (less common but
often worse) tornado wind effects that severe thunderstorms (some of which
have deceptively little lightning and thunder, especially in off-season)
have!
LA is a minor improvement, being in a minor tornado hotspot of "western
USA" bad enough to be only a minor improvement over the USA east of the
Rockies! Worse still - irregularity of tornadoes and other severe
thunderstorm wind effects (often there with minor uptick from the
unimpressive low lightning/thunder incidence that is normal there) -
mostly during an El Nini winter rainy season! Along with bad windstorms
other than tornadoes heavily occurring during El Nino winters, and with
high incidence of bad winds worse-than-average being worse near/above
1,000 feet than at treetop level!
If a big building is so touchy that 1/2 inch off out of 400 feet is a
big structural problem, then the building design has a big structural
problem on the drawing board!
- Don Klipstein (don@misty.com)
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Posted by William Noble on November 20, 2006, 2:52 am
this all makes several invalid assumptions, one being that the earth is
nearly spherical, the other that gravity is uniform - see WGS-84 for example
for datums for earth parametrics
> wrote:
>>
>>in
>>>... For a tall building building to be "truly plumb", *each wall* would
>>>have to
>>> be plumb, ie, lie exactly along the *line of the earth's radius*, from
>>> the
>>> point where sed wall touches the ground.
>>>
>>> *Necessarily*, then, the walls of a tall building must **diverge**, just
>>> as
>>> the earth's radii diverge, from the earth's center to the base of the
>>> building.
.com)
--
Posted via a free Usenet account from http://www.teranews.com
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