Joseph and Choi of Thornton Tomasetti to co-chair Council on Tall Buildings and Urban Habitat's Outrigger Design Working Group

Thornton Tomasetti Irvine principal Leonard Joseph, P.E., S.E. and New York senior principal Hi Sun Choi, P.E., LEED AP have been named co-chairs of the Council on Tall Buildings and Urban Habitat's Outrigger Design Working Group. The working group, which also includes co-chairs Neville John Mathias from Skidmore, Owings & Merrill and Dr. Goman Wai-Ming Ho from Ove Arup & Partners Hong Kong, is currently developing the first-ever outrigger system design guide, which will provide an overview of the history, design considerations and recommendations for outrigger systems. It is expected that the guide will be published this year. With more than 35 years of experience, Joseph has analyzed, designed and reviewed high-rise buildings, sports facilities, hangars, hotels, historic buildings, manufacturing facilities and parking garages. Choi has more than 18 years of experience in structural analysis, investigation, design and review of a variety of building types, including commercial and residential high-rise properties. Key Points * The design guide will describe in detail the application of outriggers within the lateral load resisting systems of tall buildings, effects on building behavior and recommendations for design. It will also address concerns specific to this structural system such as differential column shortening and construction sequence impacts. * The document will illustrate the impact of outrigger systems on tall building designs and demonstrate ways in which the technology of such systems is continuously advancing. Project examples will be presented for various types of outrigger systems. * Joseph has worked in a wide variety of materials, including structural steel, reinforced concrete, precast and post-tensioned concrete, masonry, wood and light gage framing. * His project credits include Shanghai Tower and Ping An International Financial Center in China; Taipei 101 in Taiwan; and the Petronas Twin Towers in Malaysia. * Joseph graduated from Cornell University with a bachelor's degree in civil engineering, and from Stanford University with an MBA and a master's degree in structural engineering. * Choi's expertise includes the design of super tall buildings for seismic risk assessment, building motion due to wind, performance-based design, and waterfront developments on reclaimed land. * Her key projects include Barclays Center and Queens Crossing in New York City; We've the Zenith, Metapolis and Incheon 151 in South Korea; Shanghai Center in China; Socar Tower in Azerbaijan; and Lotte Center Hanoi in Vietnam. * Choi holds a bachelor's degree in civil engineering from the Cooper Union and a master's degree in civil engineering from the Massachusetts Institute of Technology. Joseph said, "The most important thing a guideline can do right now is to prioritize the issues. Some people requested that we produce a complete how-to manual, which would extend far beyond our few dozen pages. Also, every building is different. It is a very dangerous mistake to think if you just follow these steps, you will come up with the right answer. You really have to look at the building and understand how it behaves to determine the right approach. However, presenting some basic principles of outrigger design certainly makes sense." Choi said, "Although outrigger systems are common in building construction, the outrigger system is not listed as a seismic load resisting system in any code, so the response modification factor R for this system is not defined per code. While we hope to make the guidelines as complete as possible, this really is just the beginning. We hope it will serve as a platform for others to contribute ideas, new approaches and strategies, which will likely be added to subsequent versions of the document."