BUILDING BIG: Databank: Georgia Dome

On March 1, 1992, as workers placed the last fabric roof panel in place, the Georgia Dome became the largest cable-supported fabric roof in the world. Stretching more than 395,000 square feet, the Teflon-coated Fiberglas fabric roof is quite an engineering marvel. The roof weighs just 68 pounds, but it is strong enough to support a fully loaded pickup truck. How? The answer lies with a fundamental engineering breakthrough, one that architect-engineer Buckminster Fuller dubbed "tensegrity."

Put simply, tensegrity is a complex sequence of triangles. Short, vertical posts carry the weight of the Georgia Dome roof. The posts are held in place by pre-stretched cables, attached to the top and bottom of each post with steel pins and welded connections. The cables pull on the posts with equal force in all directions to form strong, taut triangles. The cable roof is secured to a reinforced concrete ring along the perimeter of the dome. The 2,750-foot concrete ring rests on slide-bearing Teflon pads that allow the roof to flex slightly during high winds.

It is this precise dance of pulling and pushing that allows tensegrity roofs like the Georgia Dome to soar far above the stands and the playing field below.

Fast Facts:

The Georgia Dome contains 110,000 cubic yards of concrete, enough to build a sidewalk from Atlanta to Cincinnati.
The dome is as tall as a 29-story building, as tall as an average redwood tree, and three feet taller than the United States Capitol building.
At a rate of 750,000 gallons of water per second, Niagara Falls would take 12 minutes to fill the Georgia Dome.
The Georgia Dome contains 8,300 tons of reinforced steel -- more than the weight of iron and steel used in the Eiffel Tower.