From the Nibelungs to the digital twin

ASC GmbH: The German Federal Institute for Materials Research and Testing (BAM), Berlin, is breaking new ground in future-oriented structural testing and monitoring of buildings. As part of the DFG priority program SPP 2388 "One hundred plus – Extending the service life of complex building structures through intelligent digitalization" (SPP 100+), which uses the historic Nibelungen Bridge in Worms as a demonstration and validation object, the BAM is carrying out a project to develop new, pioneering methods for digital structural monitoring and proactive maintenance management. On board: smart ASC sensor systems from the ASC AiSys® ECO series.

Safety and sustainability

The condition of a structure can be affected by evolving material fatigue as it ages due to stress. Although bridges and other critical infrastructure are generally designed for a long service life, wear and degradation can take effect after around 40 years.

To extend the economic usability of complex building structures, significantly more measurements are required at a much earlier stage than is common today. "In our research project, we want to remedy this deficit and develop a predictive maintenance approach that can be quickly transferred to other comparable structures based on valid reference data," explains Dr. Ralf Herrmann, scientist at the BAM’s Structural Health Monitoring division.

But it is also about the sustainability of transport infrastructure. "We want to help keep structures in optimum condition with less effort so that they can be used for longer. This also applies to structures of historical and engineering significance, such as the Nibelungen Bridge in Worms, as well as bridges in the highway and railroad network.

Smart reference data for preventive monitoring

Since May 2023, two complementary structural health monitoring systems have been in operation on the Nibelungen Bridge Worms as part of SPP 100+, which collect basic data on current stress conditions at relevant measuring points. These provide a realistic picture of the structural loads and environmental impacts, and are supplemented by the recording of additional load-related vibrations caused.

In the first SPP phase, each of the 20 projects can add further, individual sensor applications to the validation structure or carry out their own measurements. BAM used this opportunity to install smart ASC AiSys® ECO-3321-008-CAN accelerometers specially configured for the conditions of the test bridge. By expanding the overall system to include vibration monitoring, additional reference data for the predictive monitoring of the condition of this and similar bridges is now being recorded, digitally transmitted and evaluated.

The innovative MEMS-based acceleration sensor systems from ASC offer a good complement to traditional, reference-based monitoring methods. Their precise, dynamic real-time deviation measurement expands the range of applications. Their easy installation increases flexibility and offers valuable additional possibilities.

Digital twin for safe bridge operation

Further, the CAN bus capability of smart sensor technology comes as one major advantage. Not only can sampling rates and measuring ranges be configured flexibly, but filter settings and frequency analyses are also integrated already. This allows for the efficient adjustment of the setup from a computer, without having to go to the bridge every time to pull new cables to the data acquisition systems.

"This enables us to provide well-founded answers to specific technical questions – including for other bridges that have been in service for a long time," explains Herrmann. Smart sensor systems on the structure can be used to record data and link it digitally to a data platform. There, they are integrated with structural information, basic historical knowledge and external factors. Mathematical algorithms use this complex mix of data to calculate models for estimating the condition of the bridge: its digital twin. Using this model and continuously adding further data and load profiles, future requirements, change processes in the structure and materials as well as maintenance and repair requirements can be estimated in good time.

Innovative partners for pioneering solutions

Digital data transmission and evaluation in real time based on the ASC AiSys ECO provides a solid yet flexibly adaptable basis for such an enormous monitoring scope. The sensors offer exciting new possibilities due to their special new features – such as high-frequency data sampling, advanced filtering and data reduction, double integration and drift correction, real-time adaptive DC offset compensation, phase correction and elimination of unwanted influences, as well as integrated data processing and output.

"What we particularly like about the ASC team in the field of research is that we can discuss ideas and requirements, clarify questions and solve problems in direct conversation. That's not a given in this market."