T.Y. Lin International (TYLI), a globally recognized full-service infrastructure consulting firm, announces that the San Francisco-Oakland Bay Bridge New East Span (East Span) has won the International Association for Bridge and Structural Engineering (IABSE) Outstanding Structure Award 2015. This prestigious, annual award is given to a single project that IABSE has named “the most remarkable, innovative, creative, or otherwise stimulating structure completed within the last few years” worldwide. TYLI, in a joint venture with Moffatt & Nichol, served as Engineer of Record on the East Span project and was responsible for the design engineering of the iconic, seismically-resilient bridge.
The IABSE Outstanding Structure Award Committee 2015 made the following statement about the East Span: “With a ground-breaking advanced bridge design, the San Francisco-Oakland Bay Bridge New East Span demonstrates how innovations in seismic engineering can become the bridge to making history.”
The East Span, which is located between two faults capable of producing destructive earthquakes, is a designated regional Lifeline Structure with a 150-year design life and designed to be able to open to emergency traffic shortly after a major seismic event. The signature bridge comprises four seamless, interrelated components: the world’s longest, single-tower Self-Anchored Suspension Span (SAS) at 624 meters, also the world’s widest bridge at 79 meters; the 1,900-meter Skyway, the longest East Span portion, which ascends from the Oakland shoreline to the SAS; the Oakland Touchdown, connecting the Skyway to a major California freeway; and the Yerba Buena Island Transition Structure (YBITS), which links the SAS to the east portal of the Yerba Buena Island (YBI) tunnel.
“We are deeply honored to have our work on San Francisco-Oakland Bay Bridge New East Span recognized by the International Association for Bridge and Structural Engineering,” said Marwan Nader, Ph.D., P.E., TYLI Senior Vice President, Technical Director for the firm’s global Bridge Line of Business, and Lead Design Engineer for the SAS. “This tremendous effort has led to a unique and elegant structure that is the perfect addition to the world-class bridges in the greater San Francisco Bay Area.”
Engineering innovations and advancements found in TYLI’s design of the East Span include the use of shear link beams in the single, 160-meter-tall SAS tower, which supply the distinctive tower with the required stiffness, absorb seismic energy, and limit damage in the tower shafts. A single, 1,387-meter-long looped suspension cable anchors in the SAS superstructure itself rather than in the ground at either end due to unique geological conditions.
“The San Francisco-Oakland Bay Bridge New East Span project came with complex design engineering challenges, such as the region’s high seismicity and the San Francisco Bay’s formidable geological features,” said Sajid Abbas, Ph.D., P.E., TYLI Senior Vice President and Lead Design Engineer for the Skyway portion of the bridge. “As a result, T.Y. Lin International included innovations in bridge design and seismic engineering technologies in order to accomplish our primary goal: to provide the highest levels of seismic safety for Bay Area communities.”
The Skyway foundations comprise 2.5-meter-diameter raked piles that extend 90 meters below the water line to stable soil strata. For increased seismic resilience, 18-meter-long hinge pipe beams and specially-designed expansion joints were incorporated in the bridge decks to allow emergency traffic to cross the bridge after a major seismic event.
The East Span project was led by the California Department of Transportation, working in conjunction with the Metropolitan Transportation Commission, and the California Transportation Commission. TYLI and its project partners accepted the Outstanding Structure Award 2015 at the IABSE Conference 2015 in Geneva, Switzerland on September 23, 2015.