Watch the exclusive full episode of "Modern Marvels: Sears Tower"

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Architecture ,Engineering and Construction

• The superstructure consists of nine interlocking (square)tubes (Bundled tube system) that terminate at different heights, creating the iconic stepped-back appearance of the tower.The sides of the squares are 75 feet (for an overall width of 225 x 225 ft btw. exterior column lines and 229' at outside faces). Height to width ratio is 6.45:1
  
  
• This "bundled-tube" configuration was a revolutionary engineering concept at the time, pioneered by SOM's very own Fazlur R. Khan.

• Each tube is a rigid steel frame that performs in tandem with its neighbor to efficiently counteract all lateral and gravity loads. (This is in contrast to the popular tube-in-tube system, in which a rigid network of floor diaphrams and closely-spaced exterior columns work in unison to resist lateral loads whereas a centralized core functions to carry vertical loads exclusively.)

Click Here to view Bundled tube system and Here for Tube-in-Tube system

• It allowed for large open office spaces on the lower levels and smaller floor plates on the upper levels with unobstructed views of the cityscape.Sears, Roebuck and Company reside in the lower level .

• To aid in occupant comfort, belt trusses were rigged on the upper mechanical floors thereby further reducing shear forces (i.e. wind-induced sway).

• Building automation was a primary design consideration as well. For fire, security, and HVAC monitoring and control, engineers opted for a Honeywell computer system, one of the largest such networks ever installed at the time.

• Another technological innovation was the robotic window washers that could be programmed to descend along tracks built into the curtain wall. Currently, they operate eight times per year.

• Vertical transportation was also crucial. Designers had to ensure efficient flow of pedestrian traffic throughout the building — which, on any given day, could number in the tens of thousands. Westinghouse Electric Corp. employed "skylobbies" for this purpose, a system which Otis Elevator Co. Designated transfer-floors would be served by banks of double-deck express elevators. Separate banks of local-service elevators would carry passengers to their final destination.

Early stage of construction

Later stage of construction

Brief Hi'STOREY'

The construction of Sears Tower began in August 1970 and the building reached its originally anticipated maximum height on May 3, 1973 .When the Sears Tower was completed in 1973 it surpassed One World Trade Center in New York City, completed earlier that year as the World’s Tallest Building. It stayed the worlds tallest building from 1973 to 1998, when the Petronas Towers in Malaysia surpassed it( because of the spires atop the buildings).The Sears Tower still remained the world's tallest building, counting by roof height until fall of 2004, when Taipei 101 in Taiwan was completed, 19 feet taller than the Sears Tower’s roof.

The tower is 108 stories tall as counted by standard methods, though the building owners count the main roof as 109 and the mechanical penthouse roof as 110. The distance to the roof is 1,451 feet (442 m), measured from the east entrance.

Two television antennas were added to the structure in February 1982, increasing its total height to 1,705 feet (520 m). The western antenna was later extended to 1,730 feet (527 m)^[4]June 5, 2000 to improve reception of local NBC station WMAQ-TV. As a result of this it used to be the tallest building to the tips of the antennas till August 12, 2007, when the Burj Dubai (1,921.6 feet, 585.7 m) in Dubai, United Arab Emirates was reported by its developers to have surpassed the Sears Tower in all height categories.

A comparison of the heights is shown below.(click to enlarge)

SKY IS THE LIMIT

The Chicago skyline is one of the most picturesque views in the world.It is also the tallest.Among the soaring peaks kissing the sky, one monumental MEGASTRUCTURE stands out bearing testimony to the fact 'its lonely at the TOP'. This 145o ft ,110 storey icon has been the tallest building in United states since 1973. It is the tallest buiding in the whole of North America.It was also the world' s tallest building from 1973 to 1998.
This is the Sears Tower.






Commissioned by Sears, Roebuck and Company, designed by chief architect Bruce Graham and structural engineer Fazlur Khan of Skidmore, Owings and Merrill,the Sears Tower offers more than 3.8 million square feet of office and retail space.Sears Tower is THE business location in Chicago.

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SEARS TOWER , chicago