1. DFOS-based monitoring of prestressed concrete bridge girders : preliminary resultsKleo Lila, Max Herbers, Bertram Richter, Andrea Agreiter, Maja Kreslin, Petra Triller, Andrej Anžlin, Werner Lienhart, Steffen Marx, 2025, published scientific conference contribution Abstract: Due to bridges’ critical role in transportation networks, the assessment and maintenance of existing bridges have become a priority. Prestressed concrete bridges constitute a significant portion of Europe’s transportation network, yet many no longer meet today’s technical requirements. This is primarily due to two factors: (i) the unforeseen increase in heavy goods traffic, and (ii) insufficient experience with early reinforced and prestressed concrete construction methods, coupled with inadequate regulations, which resulted in design weaknesses and structural deficiencies. One critical failure mechanism, identified when recalculating existing bridges based on updated guidelines, is insufficient shear load-bearing capacity, which has prompted the premature demolition of numerous bridges. A thorough understanding and rigorous monitoring of shear behavior is essential since neglecting this problem could lead to notable consequences, especially for aging infrastructure. In this paper, a distributed fiber optic sensor (DFOS) based monitoring system, inspired by shear detection concepts, is tested. A decommissioned prestressed concrete bridge girder was equipped with a DFOS grid, allowing for detailed monitoring of crack width, location, and shape. Preliminary test results confirm the successful installation and early detection of cracks, highlighting the system’s potential to identify microcrack formation, monitor crack growth, and support maintenance strategies.
Keywords: structural health monitoring, distributed fiber optic sensors, microcracking, crack growths, load testing, prestressed concrete
Published in DiRROS: 27.01.2026; Views: 178; Downloads: 91
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2. Integrating distributed acoustic sensing for damage detection in old pre-stressed concrete girders : preliminary experimental resultsLisa Strasser, Werner Lienhart, Thomas Moser, Andrej Anžlin, Mirko Kosič, Maja Kreslin, Doron Hekič, 2025, published scientific conference contribution Abstract: In this study, we investigate the load-bearing capacity of pre-stressed concrete girders under various damage levels. We employed Distributed Acoustic Sensing (DAS) technology to monitor and quantify changes in the girder response as damage levels were incrementally introduced. This approach enabled the real-time measurement of dynamic behavior over the entire length of the girder, allowing for a detailed characterization of damage-induced structural changes. To complement the DASbased approach, we also applied classical acceleration-based damage detection techniques. By integrating these methods, we aimed to cross-validate the results and provide a more comprehensive understanding of damage progression and its impact on structural performance. The experimental campaign, conducted in Ljubljana, ZAG, involved full-scale testing of pre-stressed concrete girders subjected to controlled damage scenarios. This setup ensured a realistic assessment of the girders’ residual capacity and failure mechanisms. The paper presents preliminary results from this experimental study, emphasizing the capability of DAS measurements to detect and characterize damage, while also comparing its performance against traditional methods. By combining advanced sensing technologies with established techniques, this research highlights the potential of DAS as a transformative tool in structural health monitoring.
Keywords: distributed acoustic sensing, distributed fiber optic sensing, structural health monitoring, frequency analysis, load test, infrastructure monitoring, bridge monitoring
Published in DiRROS: 22.01.2026; Views: 219; Downloads: 127
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3. Identification of the damage types for reinforced concrete using CNN modelsYue Shi, RunYu Wang, Xue Bai, 2025, original scientific article Keywords: convolutional neural network, reinforced concrete, damage detection, image recognition, structural health monitoring, deep learning
Published in DiRROS: 01.09.2025; Views: 589; Downloads: 262
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4. Comprehensive permanent remote monitoring system of a multi-span highway bridgeAndrej Anžlin, Uroš Bohinc, Doron Hekič, Maja Kreslin, Jan Kalin, Aleš Žnidarič, 2021, published scientific conference contribution Abstract: As part of the reconstruction of a multi-span viaduct on a Slovenian highway, a permanent remote monitoring system with over 200 sensors was established. Several parameters are monitored on different parts of the viaduct by means of temperature sensors, accelerometers, strain gauges, long-gauge deformation and Fibre Bragg Grating (FBG) sensors. In this way strains, frequencies and temperatures on external prestressed beam cables, carbon fibre rebarsused for the flexural strengthening of a deck overhang, pier caps and prestressed beams are measured and stored into the on-site central data acquisition system. This paper presents architecture of the permanent bridge monitoring system and preliminary results of the measurements.
Keywords: permanent monitoring, structural health monitoring, bridge WIM, sensors, viaduct
Published in DiRROS: 22.01.2024; Views: 1665; Downloads: 1052
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5. Using statistical analysis of an acceleration-based bridge weigh-in-motion system for damage detectionEugene J. O'Brien, Muhammad Arslan Khan, Daniel Patrick McCrum, Aleš Žnidarič, 2020, original scientific article Abstract: This paper develops a novel method of bridge damage detection using statistical analysis of data from an acceleration-based bridge weigh-in-motion (BWIM) system. Bridge dynamic analysis using a vehicle-bridge interaction model is carried out to obtain bridge accelerations, and the BWIM concept is applied to infer the vehicle axle weights. A large volume of traffic data tends to remain consistent (e.g., most frequent gross vehicle weight (GVW) of 3-axle trucks); therefore, the statistical properties of inferred vehicle weights are used to develop a bridge damage detection technique. Global change of bridge stiffness due to a change in the elastic modulus of concrete is used as a proxy of bridge damage. This approach has the advantage of overcoming the variability in acceleration signals due to the wide variety of source excitations/vehicles–data from a large number of different vehicles can be easily combined in the form of inferred vehicle weight. One year of experimental data from a short-span reinforced concrete bridge in Slovenia is used to assess the effectiveness of the new approach. Although the acceleration-based BWIM system is inaccurate for finding vehicle axle-weights, it is found to be effective in detecting damage using statistical analysis. It is shown through simulation as well as by experimental analysis that a significant change in the statistical properties of the inferred BWIM data results from changes in the bridge condition.
Keywords: bridge health monitoring, bridge WIM, structural dynamics, damage detection, vehicle-bridge interaction
Published in DiRROS: 12.09.2023; Views: 1739; Downloads: 797
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6. Model updating concept using bridge Weigh-in-Motion dataDoron Hekič, Andrej Anžlin, Maja Kreslin, Aleš Žnidarič, Peter Češarek, 2023, original scientific article Abstract: Finite element (FE) model updating of bridges is based on the measured modal parameters and less frequently on the measured structural response under a known load. Until recently, the FE model updating did not consider strain measurements from sensors installed for weighing vehicles with bridge weigh-in-motion (B-WIM) systems. A 50-year-old multi-span concrete highway viaduct, renovated between 2017 and 2019, was equipped with continuous monitoring system with over 200 sensors, and a B-WIM system. In the most heavily instrumented span, the maximum measured longitudinal strains induced by the full-speed calibration vehicle passages were compared with the modelled strains. Based on the sensitivity study results, three variables that affected its overall stiffness were updated: Young’s modulus adjustment factor of all structural elements, and two anchorage reduction factors that considered the interaction between the superstructure and non-structural elements. The analysis confirmed the importance of the initial manual FE model updating to correctly reflect the non-structural elements during the automatic nonlinear optimisation. It also demonstrated a successful use of pseudo-static B-WIM loading data during the model updating process and the potential to extend the proposed approach to using random B-WIM-weighed vehicles for FE model updating and long-term monitoring of structural parameters and load-dependent phenomena.
Keywords: monitoring, bridge, viaduct, bridge weigh-in-motion (B-WIM), structural health monitoring (SHM), finite element (FE), calibration, model updating
Published in DiRROS: 29.05.2023; Views: 1548; Downloads: 870
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