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UPDATE: 2.29.08

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The Science of the Magic Carpet Roof

The Connecticut Science Center’s Magic Carpet roof is a gigantic work of art suspended nearly 250 feet from street level, and made possible by science. It is an extraordinary architectural, engineering, and construction undertaking. The roof, one of three covering the towers of the dramatic building, is up to 49 feet wide and 280 feet long.

The roof design is especially exciting because of the way each end extends far beyond the structure of the building itself. On the east side the roof extends 90 feet towards the Connecticut River. On the west side, it reaches 49 feet towards Columbus Boulevard.  These extensions, in engineering terms, are called cantilevers. 

About Cantilevers
Cantilevers extend horizontally away from a vertical support, so that there is nothing appearing to hold them up from beneath. This is a very significant area of construction technology, where science helps architects and builders create dramatic artistic shapes that appear to be magical.  About Cantilevers:Wikipedia

The Roof Correction
During routine review, the Science Center’s special construction inspector determined that the roof may not have been erected in exactly the right position. He believed that the east edge of the roof may have been hanging lower than specified in the design. After extensive surveys and other analysis, the project team confirmed that the cantilevered portions of the Magic Carpet roof were out of position.

A crane was assembled to make the appropriate adjustments to the west cantilever in the air.  These adjustments to the west side cantilever were completed in January 2008. In March 2008, work continued on the east cantilever, overlooking the Connecticut River. The design team developed a new method to provide supplemental support for the east side cantilever using a new cable stayed-type of system. 

About Cable-Stayed Systems
A cable-stayed system draws on the same engineering principles used on many bridges to support long, horizontal structures.  In a cable-stayed system, the central bearing point, (the tower in the case of a bridge), is the primary load-bearing structure.  Here’s a picture of Boston’s Leonard P. Zakim Bunker Hill Bridge, which uses a cable-stayed system as both an engineering solution and an architectural feature.

Unlike the bridge shown above, the Science Center’s support system will be hidden on the bottom inside of the Magic Carpet roof structure, as shown below, so the roof will look exactly as designed from the outside.  Instead of cables distributing weight over a center point, steel rods will extend about 50 feet on one side and 25 feet on the other side to add support to the cantilevered roof structure.  In fact, the rods are adjustable so that engineers can set the precise angle of the cantilever when it is re-erected, by tightening the nuts which connect the rods to the center point and each end. For the Science Center roof, the center point is positioned on the strongest area of the roof (indicated in green on the drawing below), and the rods connect the weight of the cantilever back to that point, and beyond, on the opposite side of the center point. 

What’s Next
To complete the corrections to the east end of the Magic Carpet roof, the cantilever structure will first be raised into position 183 feet above the plaza level.  The cable stayed-type system will then be attached to the roof and the steel rods that form the major components of the cable stayed-type structure will then be tightened to adjust the angle of the cantilevered roof to the proper position.  The result of this new design is a high level of accuracy in the roof’s position and increased structural strength.  Engineers will continually survey the work to assure that it is correct. Revisions to the east side cantilever are expected to be completed in May, which puts the schedule completion date for the Science Center building at March 2009.

Learn more about cable-stayed systems on Wikipedia. 
Click here for cable-stayed learning activities. 

Construction work on all other aspects of the project continues at a brisk pace.  Currently the building is being enclosed, utilities systems installed, floors poured, and windows secured.  Details of the progress can be viewed in our latest project update.

For additional information:
Science Center’s Live Web Cams.  
Science of Building Videos
Construction Update & Photos