Great American Tower Rooftop Tiara Wins National Architecture and Engineering Award
July 16, 2012 from American Institute of Steel Construction
(Chicago, IL) – The steel tiara that crowns Cincinnati’s tallest building, the Great American Tower at Queen City Square, has earned national recognition in the 2012 Innovative Design in Engineering and Architecture with Structural Steel awards program (IDEAS2). In honor of this achievement, members of the project team will be presented with awards from the American Institute of Steel Construction (AISC) during a ceremony at the building on Thursday, July 19 at 2 p.m.
Conducted annually by AISC, the IDEAS2 awards recognize outstanding achievement in engineering and architecture on structural steel projects across the country. The IDEAS2 award is the highest, most prestigious honor bestowed on building projects by the structural steel industry in the U.S.
The project team members include owner/developer Port of Greater Cincinnati and Eagle Realty Group, Cincinnati; architect HOK, St. Louis; structural engineer and steel detailer Thornton Tomasetti, Inc., Chicago; general contractor Turner Construction Co., Cincinnati; steel fabricator Owen Steel Company, Columbia, S.C. (AISC Member/AISC Certified Fabricator); and bender/roller Chicago Metal Rolled Products, Chicago (AISC Member).
The Great American Tower rooftop tiara is a Merit award winner in the category of projects Less than $15 Million, making it one of only four projects around the country to receive the Merit honor. Each year, the IDEAS2 awards honor National and Merit award winners in three categories, based on constructed value: projects less than $15 million; projects $15 million to $75 million; and projects greater than $75 million. Each project is judged on its use of structural steel from both an architectural and structural engineering perspective, with an emphasis on: creative solutions to project requirements; design innovation; aesthetic and visual impact of the project; innovative use of architecturally exposed structural steel; technical or architectural advances in the use of the steel; the use of innovative design and construction methods; and sustainable design and construction.
The steel rooftop tiara atop the 41-story Great American Tower is an iconic presence on the city’s skyline. The 400-ton, 130-ft-tall tiara was conceived by Gyo Obata, a founder and design principal of HOK. Obata was inspired by a photograph of a tiara worn by Diana, Princess of Wales, and by Cincinnati’s nickname, the Queen City.
“The project really used steel to create an architectural focus for the building,” commented Dan Labriola, LEED AP BD+C, a project manager with Pepper Construction Company in Tinley Park, Ill., and a judge in the competition. “The night views of the project really differentiate this building from the rest of the skyline.”
Several design iterations were required to ultimately produce a cost-effective and graceful crown. Working closely with HOK, structural engineer Thornton Tomasetti helped rationalize the tiara’s geometry and produce a structural framing layout that could easily be fabricated and constructed. Thornton Tomasetti also provided HOK with a detailed 3D Tekla model containing all proposed framing sizes, geometries and connection information. The Tekla model enabled HOK to approve the aesthetic appearance of the structure before shop drawing production, thereby facilitating a smooth shop drawing preparation and review process.
The tiara has a hyperbolic silhouette and its plan dimensions measure 159 ft in the east-west direction and 93 ft in the north-south direction. Geometrically complex, it is composed of 15 ornamental structural steel arch elements uniformly supported by 14 arching structural steel columns woven through the tiara, creating a two-way support system. It features more than 750 individual hollow structural section (HSS) elements, ranging in diameter from 4 in. to 16 in. The smallest of the tiara’s structural steel members account for nearly 50% of the pieces and serve to improve the aesthetic appearance of the structure. Fundamentally, the tiara is a self-supporting, two-way steel space frame possessing stiffness and strength both vertically and laterally.
To overcome complexities associated with the irregular geometry of the tiara, Thornton Tomasetti collaborated closely with Owen Steel Company and Runyon Erectors regarding shipping methods, delivery methods and potential erection procedures for structural steel framing members. And Chicago Metal Rolled Products was relied upon for its precision curving of the HSS sections. Loadbearing structural framing members needed to be designed to the tightest tolerances. To help ensure this, Thornton Tomasetti suggested a network of subassemblies for these members that were shop fabricated, leading to fewer construction components and allowing for geometric verification of the elements before erection began.
They also provided on-site fabrication consultation, assisting in the development of specialized tools that helped specify geometry of the members where control points were inaccessible due to their location within the volume of the HSS members. This collaborative, shop-intensive process amounted to 80% of the assembly effort, reducing the number of pieces handled in the field and resulting in a total number of field modifications not exceeding 1% of the more than 750 individual components of the structure.
The 10 IDEAS2 winners for 2012 were chosen from nearly 100 submissions received from architectural and engineering firms throughout the U.S. Each submission is reviewed and award winners are selected by a nationally recognized panel of design and construction industry professionals.
The IDEAS2 award dates back more than 70 years to the earliest years of AISC’s existence. Roger E. Ferch, P.E., president of AISC, said, “The entire Great American Tower rooftop tiara project team has shown how structural steel can be used to create structures that combine beauty and practicality. The result is a structure that serves its patrons extremely well, while providing an example of what can be achieved when designing and constructing projects with steel.”
High resolution images of the Great American Tower rooftop tiara are available upon request by contacting AISC’s Tasha Weiss at 312.670.5439, [email protected].
Photo by Rick Mayer
For more information contact:
American Institute of Steel Construction
The American Institute of Steel Construction, headquartered in Chicago, is a not-for-profit technical institute and trade association established in 1921 to serve the structural steel design community and construction industry. AISC’s mission is to make structural steel the material of choice by being the leader in structural steel-related technical and market-building activities, including: specification and code development, research, education, technical assistance, quality certification, standardization, and market development. AISC has a long tradition of service to the steel construction industry of providing timely and reliable information.
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