Monitoring Vibrations on the Jefferson City Truss Bridge

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

Field Testing of Hand-Held Infrared Thermography, Phase II, TPF-5(247) Final Report

This final report (also referred to as volume II) documents results from the pooled fund study TPF-5 (247), Development of Handheld Infrared Thermography, Phase II.  It provides a summary of field testing conducted to evaluate the capabilities of two different IR imaging technologies for detecting subsurface damage in concrete.  The IR-UTD technology collects thermal images over a period of time; these data are processed to measure thermal inertia of a material.  The IR-DSS technology automatically captures thermal images while the system is moved from one position to another.   

 In general, it was found that the IR-UTD technologies had capabilities that exceeded the capabilities of conventional IR imaging.  The technology provided highly accurate data that documented the size and shape of delaminations in bridge decks and other structures.  The IR-UTD technology also provided data on the depth of damage and could image the structural features of a bridge.  Traffic control was not required to implement the IR-UTD technology. The IR-DSS capability was demonstrated to include the ability to produce spatially-referenced images that provided accurate depictions of subsurface damage, and these data were presented to-scale in a plan-view image of an entire deck.  Traffic control was required to implement this technology, because the travel speed of the system is limited to < 10 mph.

VIEW REPORT

Report number: cmr16-007
Published: May 2016
Project number: TRyy1144
Author(s): Dr. Glenn Washer, James Dawson, Pedro Ruiz-Fabian, Ali Sultan, and Mike Trial 
Performing organizations: Department of Civil and Environmental Engineering, University of Missouri-Columbia