Odigeetria Church, Corfu – Structural Monitoring
Challenge
Odigitria church was built in 1815 and displays inevitable signs of wear and tear after 200 years in use. Those responsible for the building and its visitors became concerned following recent observation of external cracks on both the North and South walls.
An additional concern is the high level of seismic activity of Corfu, and more broadly, Greece, due to the country being located in a complex geological boundary zone at the Africa-Eurasia convergence. This means buildings in Corfu are subject to relatively frequent earth tremors and earthquakes, making it even more important that at-risk structures are carefully monitored.
Solution
Because the church remained open to visitors, civil engineering firm Laisergo and monitoring experts Landmark noted the urgent need for an immediate monitoring solution to assess the safety of the building.
Landmark recommended Senceive’s wireless remote technology due to the benefits of continuous and precise data. Frequent data sampling would ensure any trends in movement would be quickly revealed. Remote access to the data was an added benefit, as both time and cost of monitoring would be reduced compared to more traditional optical monitoring approaches.
Due to the small size of the church only four wireless sensors were needed - one Triaxial Tilt Sensor and three Optical Displacement Sensors – both with measurement repeatability of 0.0005°. The sensors were easily fixed to the masonry walls with appropriate mounts and screws.
During installation the sensors were configured to provide scheduled reporting of detected movements every 25 minutes and to send immediate alerts to stakeholders in the event of any pre-set movement thresholds being exceeded.
A cellular gateway fixed to a nearby telephone pole provided a reliable wireless communication link between the sensors on site and remote stakeholders. Online data was available immediately via Senceive WebMonitor™ software – accessible on computer, tablet or phone.
Outcome
After two months of monitoring, it was apparent that the two sidewalls were moving, with the behaviour characterised by a twisting action in which the north-west and south-east corners were moving outwards and the two other corners remained relatively stable.
Laisergo and Landmark will take the results to the Archaeology service in Greece to inform them of the movement and so they can proceed with the necessary restoration work to achieve structural integrity of the building.
The project provides a good example of how the use of just a few sensors to assess the behaviour of a small but historic building can very quickly reveal patterns of structural movement.
Financial resources for restoration of heritage structures are often scarce; structural health monitoring can help to prioritise which buildings should most urgently need maintenance attention.
Now that movement in this church has been verified, the sensors will likely be moved elsewhere to another cultural heritage site.
View the case study video here
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Created on: Tue 23rd May 2023
In a short amount of time, our team was able to use the precise data from Senceive’s wireless sensors to confirm this historic church is indeed moving.
Key Points
- Visible cracks on the walls of a 200-year-old church meant monitoring was necessary to determine if structural integrity was at risk.
- Quick and easy to deploy wireless sensors provided rapid insight into the deformation of the historic building.
- After less than two months of data sampling, it was clear that two diagonally opposite corners of the building were moving outwards in what amounted to a twisting motion.
