The objective of the research was to determine the frequency and cause of resonant vibrations of truss verticals on bridge A4497 over the Missouri River in Jefferson City, MO. Wireless accelerometer instrumentation was installed on the bridge to monitor the vibrations of four verticals over a period of 42 days. Local weather data was used to analyze the weather conditions causing resonant vibrations of the verticals. Eleven vibration “events” were identified in which the vertical members vibrated with higher than normal accelerations. It was concluded that the frequency of resonant vibration events is likely 0.25 events per day or less. Based on the monitoring results, the vibrations are caused by average winds from the WNW/NW or SW of ~17 mph or greater. Based on the research, recommendations included: 1) The effect of the vibration events on the durability of the members should be analyzed further to determine if a retrofit is necessary. The data provided through the field monitoring should be used in the analysis; and 2) Other vertical members of a similar length should be monitored to determine if they are affected by resonant vibrations.
VIEW REPORT
Report number: cmr16-012
Published: May 2016
Project number: TR201605
Author(s): Glenn Washer, Pedro Ruiz Fabian, James Dawson
Performing organizations: University of
Missouri-Columbia Department of Civil & Environmental Engineering
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