The world’s tallest building and a glassed-enclosed viewing platform at the skyscraper that used to hold the record were the top winners Saturday night as the Structural Engineers Association of Illinois presented its excellence in engineering awards for 2009.

Burj Khalifa
Burj Khalifa

Skidmore, Owings & Merrill of Chicago won the most innovative structure honor for the Burj Khalifa (left), the 2,717-foot-tall, mixed-used Dubai tower that opened last January and easily surpassed a skyscraper in Taiwan to claim the world’s tallest title.

The firm of Halcrow Yolles won the jurors’ favorite award for The Ledge at Willis Tower, whose glassed-in window bays–complete with glass floors–seem to suspend tourists high above the sidewalks of Chicago. At a height of 1,451 feet, the Willis (formerly Sears) Tower reigned as the world’s tallest building from 1973 to 1996.

Magnusson Klemencic Associates won the best large structure award for Aqua, whose undulating balconies create an iconic image for the 82-story mixed-use Chicago tower.

Halvorson and Partners received the best medium structure honor for the United Arab Emirates pavilion at the Shanghai World Expo.

The Burnham Pavilions at Millennium Park, which were engineered by Rockey Structures, won best small structure honors.

The awards were presented at Preston Bradley Hall of the Chicago Cultural Center.Projects completed since Jan. 1, 2007 were eligible.

I was priviledged to be one of the jurors for these honors. Here are my comments on the winners:

MOST INNOVATIVE STRUCTURE—Burj Khalifa—This soaring tower achieves its unprecedented height and superb skyline silhouette through bold advances in structural design, construction technology and wind tunnel analysis. It is a classic Chicago synthesis of architecture and engineering, richly representing the quest for innovation that has long been part of Chicago’s design DNA.

JURORS’ FAVORITE—The Ledge (above left)–A small but striking addition to the tallest tower in the Western Hemisphere, this jewel-like viewing deck winningly joins state-of-the-art glass technology with almost-invisible structural and mechanical systems. Its remarkably transparent bay windows  give visitors a heart-racing lookout point, breathe new life into an iconic skyscraper and vividly demonstrate the value of sound engineering to the broader public.

BEST LARGE STRUCTURE—Aqua—The dazzling rippling effect of Aqua’s curving balconies and its attractively slender proportions were created in concert with structural engineers who played an essential supporting role in its captivating skyline drama.

BEST MEDIUM STRUCTURE—United Arab Emirates Pavilion—The handsomely, dune-like form of this expo pavilion (in rendering, at left) owes a considerable debt to innovative design and construction technologies, from a diagrid shell structure to “form-finding” structural analysis to bolted connections that will allow the pavilion to be deconstructed and rebuilt in its home country.

BEST SMALL STRUCTURE—Burnham Pavilions—Despite the durability problems these pavilions encountered through heavy public use in Chicago’s Millennium Park, their anything-but-conventional internal structures proved robust, putting engineering in the service of adventurous, eye-popping architecture and ambitious urban planning.

For additional information about the awards program, including a listing of last year’s winners, go to this link.