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Report No.: CCEER-13-1

Title: Instrumentation and Dynamic Characterization of the Galena Creek Bridge

Authors: Carr, T. and Sanders, D.

Date: January  2013

Performing Organization:
Department of Civil Engineering/258
University of Nevada, Reno
Reno, NV 89557

Abstract:

The Galena Creek Bridge is a concrete arch bridge that was completed in 2012 as part of the I-580 freeway in Northern Nevada. The research in this report covers the instrumentation and in–field experiments conducted to dynamically characterize the structure in its baseline condition.

A system of accelerometers was installed in the superstructure of the bridge and several experiments were performed to determine its basic dynamic characteristics. Live loading through the use of construction haul trucks produced excitation in the vertical direction. An eccentric mass shaker was then used to excite the bridge transversely. Acceleration data collected from these experiments was compared to predictions from analytical models. The truck live loading was difficult to recreate through dynamic modeling. The comparison between experimental data and analytical data shows that the analytical models typically underestimate the acceleration values experienced by the real bridge. From the mass shaker data, basic modal properties were calculated, and a reasonable correlation is seen between the experimental data and analytical data. The damping of the structure was calculated from the experimental data to be 2% vertically and 3% transversely, typically.

The instrumentation system will now serve as a permanent health monitoring system for the bridge. Future experiments may be performed and compared to the results presented here to determine any changes that may occur in the bridge’s properties. Additionally, the monitoring system will be able to capture the structure’s behavior in seismic events.

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