Description:
EngAnalysis deployed a customized structural health monitoring system to monitor and quantify the extent of bearing and abutment movement that is occurring in this heritage listed bridge structure.
Our client wanted the following questions answered in order to understand and manage their risk on the bridge:
- If and how the abutments are moving in a cumulative manner over time?
- The extent of movement with respect to live load and thermal cycling
- Are the bearings operating as designed?
- Is the truss propping the abutments?
Sensors and Hardware
We specified and installed a custom system to meet the monitoring scope which included tilt sensors, laser displacement sensors, strain gauges, cameras, weather sensors, data aggregation and modem.
Our system was powered by a local solar installation with battery storage and the modem software was configured to collect data, package and transmit to EngAnalysis servers.
Results and Data Analysis
A key part of the success of our projects is our experience and capability in data analysis and reporting. Using the strain gauges, we were able to detect and identify high frequency train movements on the bridge , so that results from “live load events” could be separated from thermal cycles.
We found excellent correlation of the bearing and abutment displacements with temperature and were able to report to our client the extent of movement. One of the exciting results of the analysis we undertook was that we were able to compare:
- Predicted movement due to thermal expansion
- Measured bearing movement
- Equivalent length change due to strain development in truss chords
We found the calculated predicted movement very closely matched the cumulative measured bearing movement and strain development in the truss which gives great confidence in the monitoring outcomes.
We used our video installation to verify the measured movements, and were able to see the bearings moving with thermal cycles!
