Intelligent, networked systems for structural monitoring

The safety and durability of transport and building infrastructure are in the interests of both operators and users. To maintain the best possible building condition at the lowest possible cost, effective monitoring is required to improve condition assessment.

Although there are suitable monitoring systems, they are usually not properly networked, not directly integrated into the building management system and their data is often not usable in the long term due to incomplete documentation and non-standardized evaluation procedures.

In the PreMainSHM project, a team at Graz University of Technology (TU Graz) led by Markus Krüger from the Institute of Technology and Testing of Construction Materials (IMBT) and Werner Lienhart from the Institute of Engineering Geodesy and Measurement Systems (IGMS) has tackled this issue and developed a preventive structural monitoring system with intelligent, networked systems that can be integrated directly into standard structural management software.

Data must be usable

“The technologies we have for infrastructure monitoring provide a lot of data that complement each other well,” says Werner Lienhart.

“But simply collecting data aimlessly is not helpful for forecasting the development of the building’s condition and its service life, including proactive maintenance planning.

“Our aim was therefore to develop a holistic solution that would make it possible to gain directly usable findings from structural monitoring for service life forecasts and maintenance planning in a long-term and cost-efficient manner. This allows building operators to act proactively rather than reactively.”

The centerpiece of the project was the intelligent linking of various monitoring technologies. A crucial role is played by the high-precision fiber-optic monitoring developed at the Institute of Engineering Geodesy and Measurement Systems, which provides detailed insights into material behavior, as well as cost-effective and flexible wireless sensor networks, which have been further developed at the IMBT.

By combining these technologies, comprehensive data on the condition of and stress loads on structures can be recorded. The researchers paid particular attention to the application of the FAIR data principles (Findability, Accessibility, Interoperability, Reusability) in order to ensure the long-term usability and exchange of the data obtained.

Linking with BIM and GIS

To close the gap between data acquisition and building management, the project partners developed a simple but flexible, entity-based data model. This model enables a hierarchical structuring of the buildings and links the measurement data with the corresponding components and sensors.

This facilitates access to relevant information and enables interoperability with other software systems such as BIM (Building Information Modeling) and GIS (Geographic Information Systems). A digital twin was also implemented to visualize and manage the building data.

It was also important to ensure that the sensor data collected was reliable. Although sensors are currently calibrated in advance, this is done under controlled conditions that are rarely found in a building. Instead, the temperatures and humidity change and there are other influences such as vibrations. To this end, the project team developed appropriate methods that take into account the influence of the environment on the sensor data.

Practical testing on Laxenburg Bridge

The practical testing and validation of the developed concepts took place at Laxenburg Bridge in Vienna. Various sensor technologies were used there, including wireless sensors for monitoring inclinations and crack widths as well as fiber-optic systems for high-resolution strain measurement and crack detection under traffic load.

“PreMainSHM has demonstrated the potential of intelligent and networked structural monitoring for the safe and sustainable maintenance of buildings and infrastructure,” says Markus Krüger.

“This potential must now be utilized to make the management of bridges and other engineering structures fit for the future. That’s why we have also created a guidance document in the project, which should help to ensure that future monitoring projects not only provide data, but also usable information for well-founded decisions in building management.”