Damage detection

Västerbron in central Stockholm is a steel arch road bridge and is one of the major bridges in Stockholm, opened in 1935. The bridge has a total length of about 600 m, 340 m of which stretches over water. The bridge consists of three sections where two of the sections (steel arch sections) crosses over the water and one section (concrete beam section) crosses over a park area.

A wireless sensor system was installed in June 2020. The system consists of 5 strain gauges, 1 inclinometer, 2 three directional accelerometers and 1 temperature sensor. The IoTBridge Bridge Monitoring System is used. This includes sensor integration modules, wireless gateways, communication modules, MQTT Message Broker, GOST database for aggregation and storage of measurements and cloud infrastructure with algorithms and machine learning modules.

Bridge condition assessment is generally based on information obtained by inspection and monitoring. Visual and manual inspections of bridges in Europe costs every year large sums, they are time-consuming and also unsafe. Traffic continues to rise which increase the wear of the structure and at the same time makes it very difficult to get access time for inspection. Transportation infrastructure such as bridges are subjected to several types of exposures (e.g. weather events and scour/erosion due to high flow of water), loading (e.g. traffic) and material deterioration/degradation processes (e.g. corrosion and fatigue). To make condition assessment more efficient, different techniques are used today. Internet of Things (IoT), AI and sensor technology can help monitor bridges: both wired and wireless sensors are used to measure physical quantities such as accelerations, strains and displacements. Especially acceleration data is very useful as it provides information on changes of the structural stiffness and can be used for damage detection and model updating purposes.

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