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Due to its topography, Austria has a dense network of bridge structures. Many of these structures have now been in operation for several decades and will reach the end of their normal service life in the next twenty years. At the same time, traffic volumes are increasing, and with them the number of load cycles to be endured. Prestressed concrete bridges are particularly affected: the tendons inside the concrete are susceptible to corrosion, cannot be inspected visually and therefore pose a safety risk. The challenge is twofold: on the one hand, existing structures must remain reliably usable for much longer, and on the other hand, sustainability issues are becoming increasingly important in bridge construction. The use of recycled concrete and clinker-reduced cements is considered promising, but has not yet been comprehensively investigated. This makes new diagnostic tools, prediction models and sustainability assessments indispensable.
Project objectives: Holistic solutions along three lines of development
The NINA (Sustainability-Optimised Infrastructure) research project addresses these issues with an innovative, interdisciplinary approach.
- New methods for damage detection
- Further development of acoustic emission analysis for early detection of wire breaks.
- Combination of several fibre optic measurement methods (distributed acoustic sensing, distributed strain sensing) for comprehensive, reliable monitoring.
- Development of new criteria such as ‘crack before break’ and wire break gap width model for realistic representation of damage processes.
- Reliability and service life assessment
- Integration of location-specific traffic and temperature models that take into account climate and traffic developments in addition to historical data.
- Quantification of the remaining service life of bridge structures based on combined monitoring data and load models.
- Expansion of existing safety concepts to better reflect fatigue behaviour and shear force reserves.
- Life cycle assessment and sustainability
- Analysis of the global warming potential (GWP) of different measures.
- Assessment of the potential of recycled concrete and clinker-reduced cements in new construction and bridge reinforcement.
- Development of systematic assessment criteria that quantify the ecological effects of construction measures, including traffic-related emissions.
The results are transferable guideline modules for evidence-based assessment of prestressed concrete bridges and innovative measurement and monitoring methods embedded in digital twins for real-time monitoring.
AIT contribution: Precise models and systematic sustainability assessment
The AIT Austrian Institute of Technology is taking on key tasks in the areas of load modelling and life cycle assessment in the project.
- Traffic models: Based on actual measured axle loads, location-specific load models are being developed that enable significantly more precise forecasts than today's standard approaches.
- Temperature models: Virtual sensing techniques can be used to model local temperature profiles without the need to install additional sensors in the structure. Particular attention is paid to abrupt temperature drops, such as those that played a role in the collapse of the Carola Bridge.
- Life cycle assessment: In addition to direct emissions from the measures implemented, the AIT analysis also takes into account indirect effects from traffic influences – a dimension that has rarely been considered to date, but which is crucial for the overall assessment.
‘We bring together innovative measurement methods, assessment models and sustainability: with fibre optic monitoring and sound emission, we can detect tension wire breaks at an early stage; with location-specific traffic and temperature loads, we can make more precise assessments; and with the life cycle assessment, we show how safety and climate protection can be strengthened together,’ explains Marian Ralbovsky, researcher at AIT and project manager of NINA.
Interdisciplinary consortium: From research to construction practice
Partners from research and industry are working closely together on NINA, combining expertise in building ageing, inspection, measurement technology, structural assessment, sustainability analysis and construction practice to create a comprehensive solution. The partners are:
The project is funded by the FFG as part of the program Mobilitätswende 2024/2 – Mobilitätssystem.
Conclusion: Using bridges longer, more safely and more sustainably
The NINA project is creating a holistic research and development programme that combines new measurement methods, reliability models and life cycle assessments into a continuous process. The results provide practical foundations for the maintenance and further development of Austria's bridge infrastructure – safer, more precise and more climate-friendly than was previously possible.