Methods for Life Time Extension of Railway Bridges with Active Elements (T01*)

• Subject Area: Structural Engineering, Building Informatics and Construction Operation
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 279064222

The aim of this transfer project is the development, implementation, and experimental demonstration of a system for extending the service life of existing railway bridges through active vibration reduction. The focus is on the use of hydraulic actuators that can respond to a wide range of dynamic loads and thus effectively reduce fatigue effects on structures. The project builds on previous work from the CRC 1244, particularly on experience gained with the adaptive high-rise demonstrator D1244. Trains generate periodic loads that induce vibrations in bridges. The excitation frequencies largely depend on the ratio between train speed and the largest axle spacings. The number of load cycles a bridge can withstand is primarily determined by the vibration amplitude, which is especially high near natural frequencies but can also cause fatigue outside this range. Therefore, an effective approach to prolong service life is to reduce vibrations over a wide frequency range. State-of-the-art systems are typically vibration dampers that manipulate the interaction between inertia and internal forces. These systems include passive Tuned Mass Dampers (TMDs), which are usually tuned to specific natural frequencies and are thus only partially effective under varying excitation frequencies. In contrast, the system developed in this project directly manipulates the external forces using actuators that are effective across a wide, continuous frequency range. The focus is on steel trough bridges, which offer great potential for life extension, because they are widely used and often approach the end of their service lives. The new system is based on the application of a moment boundary input, implemented using hydraulic linear actuators and a lever-arm mechanism at the bridge support on one end of the bridge. The research project initially comprises the development and control of the new system. This includes the design of the actuator components, the development and configuration of the hydraulic system, as well as the design of a control strategy for vibration reduction, taking into account the structural feedback effects on the hydraulic system and its nonlinear dynamics. A central element of the project is the experimental demonstration of the new system on an out-of-service bridge in Cottbus under artificial excitation. For comparison, a passive, semi-active, and active TMD will also be installed and tested. Furthermore, an online estimation method for estimating individual axle loads and the bridge’s state will be developed and tested on a parallel, in-service bridge. The then known load information will be employed in the vibration control and for fatigue monitoring to assess the service life extension. The application partners are MAURER SE, Liebherr COK, DB InfraGO AG, which provides the test bridges, and the German Centre for Rail Transport Research (DZSF).

• DFG Programme: Collaborative Research Centres (Transfer Project)
• Subproject of: SFB 1244: Adaptive Hüllen und Strukturen für die gebaute Umwelt von morgen
• Applicant Institution: Universität Stuttgart
• Business and Industry: DB InfraGO AG; Liebherr-Components Kirchdorf GmbH; Maurer Engineering GmbH
• Project Heads: Professor Dr.-Ing. Manfred Bischoff; Professor Dr.-Ing. Oliver Sawodny