Message - Re: Tower-Skyscrapper.. What's the difference???

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Posted by  MAT on October 29, 2003 at 21:48:14:

In Reply to:  Tower-Skyscrapper.. What's the difference??? posted by Djati on March 13, 2000 at 01:54:07:

Another View: Sear's Tower - World's Tallest Building
by John Zils, Associate Partner - Skidmore, Owings & Merrill LLP

Click 1 or 2 for accompanying diagrams

Since 1973, Sears Tower has held the undisputed title of "World's Tallest Building." Only
the Empire State Building held the title for a longer period of time (1931-1972). Recently,
the Petronas Towers in Kuala Lumpur, Malaysia topped off their building with a 242-ft-tall
spire, bringing the total height of the building to 1,483 ft. This height, measured to the top
of the Petronas Towers' spires, exceeds the height of the 110th floor of Sears Tower by 33
ft. As a result, Petronas Towers claims to be taller than Sears Tower and, therefore, the
new "World's Tallest Building." At this point, a closer look at the criteria used for
determining building height is in order.

Currently, the Council on Tall Buildings and Urban Habitat (CTBUH), headquartered in
Lehigh, Pennsylvania, defines building height as the height "measured from sidewalk level
of main entrance to structural top of building (television, radio antennae and flag poles are
not included)." This definition allows for the inclusion of decorative, architectural,
nonfunctional tops or spires but does not allow it to be included if the spire is functional
(antenna, etc.). The logic defies explanation, other than to say that is the way it is.

However, I believe that even this definition has not been consistently applied to each
building. Sears Tower was designed and constructed to include two 12-ft-diameter steel
tubes, which emanate from the building's structure at the 106th floor and project above the
110th floor an additional 68 ft - for a total building height of 1,518 ft. These two structural
steel tube bases were constructed as part of the original structure of Sears Tower, and the
building remained in that configuration until 1982. In 1982, antennae were designed and
mounted on these two existing structural bases. The 12-ft-diameter bases are clearly not
antennae, but rather extensions of the original building's structure, which were provided to
mount future antennae. Consequently, the existing criteria, when consistently applied to
both buildings, results in Sears Tower's height being 1,518 ft, rather than 1,450 ft, which
is a total of 35 ft higher than the top of the spire on Petronas Towers.

However, the author maintains that backing up a little further in our definitions to solve this
dilemma is needed. The significant word in this whole issue is the word "building." Both
Sears Tower and Petronas Towers are undeniably "buildings," so let's define what a
"building" is. A "building" is a structure which has floors, walls and roofs to enclose space
to house people. Therefore, the significant difference between a transmission tower, sign,
monument or spire is that a building has floors for the purpose of human habitation. It
seems rather clear and logical, therefore, to measure the structural component of a
"building" that qualifies it as a "building" (floor or roof), rather than a nonfunctional
component of the building (spire) - which if it were not located on top of a building would
not qualify to be measured at all. In other words, the current criteria allows for a
"nonbuilding" component to be located on top of a "building" and, therefore, extend the
height of the building. This reasoning is not logical. In fact, this criteria precipitates the
current situation, whereby an 88-story building is considered taller than a 110-story
building. Obviously, the criteria is flawed. Take one look at the accompanying graphic of
the two buildings and see if there is any doubt in your mind which building is taller. This
argument could be carried to ridiculous extremes by suggesting that we build a 1000-ft
spire on top of a 500-ft tall building and claim to be the tallest.

During the "Modernist" period of architecture, between the 1950s and 1980, this issue of
spires was not a problem; most tall buildings ended with the roof over the last floor in a
rather flat configuration. Recent architectural styles have returned to rather sculptural and
ornate building tops. As a result, the buildings "height" is extended beyond its last floor.
Petronas Towers has served to illustrate the problems and difficulties with determining a
tall building's height. We need to get back to basics and measure the element which really
defines a building - floors. By doing this, we will be measuring the true height of a
building and not an artificial extension which has no real basis for building height

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