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Publication Number: FHWA-HRT-07-008
Date: November 2006
On April 18, 1906, what came to be known as the Great Earthquake struck San Francisco, California, resulting in devastating loss of life and property. The 100-year anniversary of that catastrophic event brought nearly 500 attendees from around the world to the city for the Federal Highway Administration's (FHWA) Fifth National Seismic Conference on Bridges and Highways. Held September 18-20, 2006, the conference focused on the theme of "Innovations in Earthquake Engineering for Highway Structures." The conference also introduced FHWA's new Seismic Retrofitting Manual for Highway Structures.
Conference cosponsors included the California Department of Transportation (Caltrans), Transportation Research Board, and the Multidisciplinary Center for Earthquake Engineering Research.
"The conference's purpose was to increase awareness of seismic and geological hazards and to enhance the technical expertise of engineering professionals so they can mitigate the risk of failure or damage to our bridges and highways," says conference cochair Phillip Yen of FHWA. More than 10 countries were represented at the conference, including Korea, China, Taiwan, Turkey, Japan, Canada, Israel, and Denmark.
Conference session topics ranged from the design and analysis of major bridges and use of innovative technologies and materials to emerging design and retrofit technologies, instrumentation and monitoring systems, and lessons learned from recent earthquakes. Sessions also looked at international technologies and practices.
Innovations highlighted included Caltrans' development of a Visual Bridge Catalog to use in assessing damage and the remaining load capacity of earthquake-damaged reinforced concrete bridge elements. The catalog documents damage from laboratory experiments and historic earthquakes and classifies the performance of an array of bridge components, sub-assemblages, and systems in a consistent format. Caltrans has also developed training and inspection manuals to aid in the post-earthquake visual inspection of reinforced concrete bridges, as well as an online training class for the agency's maintenance and inspection engineers.
|Innovations highlighted included Caltrans' development of a Visual Bridge Catalog to use in assessing damage and the remaining load capacity of earthquake-damaged reinforced concrete bridge elements.|
FHWA's new Seismic Retrofitting Manual for Highway Structures made its debut at a special preconference workshop on September 17. "There was a great deal of interest in the new manual, with nearly 60 people attending the workshop," says Yen. The manual is being issued in two volumes: Part 1—Bridges (Publication No. FHWA-HRT-06-032) and Part 2—Retaining Structures, Slopes, Tunnels, Culverts, and Roadways (Publication No. FHWA-HRT-05-067). The publication is a major revision of FHWA's 1995 Seismic Retrofitting Manual for Highway Bridges. New information added includes current advances in earthquake engineering, field experiences with retrofitting highway bridges, and the performance of bridges in recent earthquakes in California and elsewhere.
Part one of the manual introduces a performance-based retrofit philosophy that is similar to the one used for the performance-based design of new buildings and bridges. Bridge performance criteria are given for two earthquake ground motions with return periods of 100 years and 1,000 years, respectively. A higher level of bridge performance is required for the event with the shorter return period than for the one with the 1,000-year return period. Retrofit criteria are recommended according to bridge performance and anticipated service life. A more rigorous performance is required for important or new bridges, for example, with a lesser level for standard bridges nearing the end of their useful life.
Part one also provides recommendations for screening, evaluating, and retrofitting bridges according to an assigned Seismic Retrofit Category. Various retrofit strategies are described and a range of related retrofit measures are explained in detail, including restrainers, seat extensions, column jackets, footing overlays, and soil remediation.
Part two of the manual focuses on the seismic vulnerability screening, evaluation, and retrofitting of retaining structures, slopes, tunnels, culverts, and roadways. It is the first known guide to formally examine how seismic evaluation and retrofitting can improve the performance of highway system structural components other than bridges.
The manual will be available this month in print and PDF formats. FHWA is looking at adapting some of the conference workshop materials and revising them as needed to serve as a new National Highway Institute course.
Planning for the Sixth National Seismic Conference in 2008 is underway, while the 2010 event is tentatively scheduled to be the first international seismic conference.
For more information on the conference or to obtain a copy of the seismic retrofitting manual, contact Phillip Yen at FHWA, 202-493-3056 (email: email@example.com). Information on the conference is also available online at www.mceer.buffalo.edu/meetings/5nsc.
|FHWA's Fifth National Seismic Conference on Bridges and Highways featured a range of sessions and exhibits on innovations in earthquake engineering for highway structures.|
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