Dynamic Testing of Alfred Zampa Memorial Bridge
Publication: Journal of Structural Engineering
Volume 134, Issue 6
Abstract
This paper describes a set of dynamic field tests performed on the Alfred Zampa Memorial Bridge (AZMB), also known as the New Carquinez Bridge, which is located northeast of San Francisco on interstate Highway I-80. The AZMB, opened to traffic in November 2003, is the first suspension bridge in the United States with an orthotropic steel deck, reinforced concrete towers, and large-diameter drilled shaft foundations. The dynamic field tests described herein were conducted just before the bridge opening to traffic. They included ambient vibration tests, mainly wind induced, and forced vibration tests based on controlled traffic loads and vehicle-induced impact loads. Four different controlled traffic load patterns and seven different vehicle-induced impact load configurations were used in the forced vibration tests. The dynamic response of the bridge was measured through an array of 34 uniaxial and 10 triaxial force-balanced accelerometers deployed along the whole length of the bridge. These dynamic field tests provided a unique opportunity to determine the dynamic (modal) properties of the bridge in its as-built (baseline) condition with no previous traffic loads or seismic excitation. Such properties could be used to validate and/or update the finite element models used in the design phase of this bridge. They could also be used as baseline for future health monitoring studies of this bridge. At the end of the paper, the ambient vibration test data were used to identify the bridge modal parameters (natural frequencies, damping ratios, and mode shapes) using the data-driven stochastic subspace identification method.
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Acknowledgments
Support of this research by the National Science Foundation under ITR Grant No. NSF0205720 is gratefully acknowledged. The joint UCSD-USC-UCLA research team who conducted the dynamic field tests reported and studied in this paper were assisted by several individuals and organizations: Brian Boal (Caltrans), Louis Bates (Caltrans Consultant Engineer), Joe Reyes (Caltrans), and Frank Daams (FCI/Cleveland Bridge). Their help is very much appreciated. The writers are also thankful to Mark Ketchum (OPAC Consulting Engineers) for very useful and interesting discussions about the conception and design of the Alfred Zampa Memorial Bridge. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the writers and do not necessarily reflect those of the sponsor.
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Information & Authors
Information
Published In
Journal of Structural Engineering
Volume 134 • Issue 6 • June 2008
Pages: 1006 - 1015
Copyright
© 2008 ASCE.
History
Received: Aug 18, 2006
Accepted: Aug 17, 2007
Published online: Jun 1, 2008
Published in print: Jun 2008
Notes
Note. Associate Editor: Sashi K. Kunnath
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