1. Monitoring the dynamic sensitivity of the Solkan footbridge to user-induced excitationMirko Kosič, Doron Hekič, Izabela Joanna Drygala, 2025, published scientific conference contribution Abstract: This paper presents a comprehensive monitoring study of the dynamic sensitivity of the Solkan footbridge in Slovenia, with a focus on its response to user-induced actions. An extensive ambient vibration measurement campaign was carried out, during which 26 triaxial accelerometers were strategically deployed along the bridge to capture its modal characteristics in all three spatial directions. The structure’s dynamic response was monitored under both regular pedestrian traffic and elevated loading conditions during a local marathon event, allowing for the assessment of its behaviour across a broad spectrum of realworld scenarios. Preliminary measurements revealed reduced pedestrian comfort, primarily due to resonance effects resulting from bridge–user interaction. The study highlights the importance of field-based dynamic assessments in diagnosing performance issues and informing mitigation strategies. The findings contribute to the advancement of resilient and dynamically efficient design and maintenance practices for pedestrian bridges.
Keywords: modal model validation, footbridges, ambient vibrations, dynamic sensitivity, user-induced excitation
Published in DiRROS: 22.01.2026; Views: 166; Downloads: 50
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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. Laboratory testing of old bridge girders : preliminary resultsMaja Kreslin, Mirko Kosič, Aljoša Šajna, Andrej Anžlin, Doron Hekič, Vladimir Požonec, Petra Triller, 2025, published scientific conference contribution Abstract: This paper presents key results on the laboratory testing of old girders removed from a flood-damaged bridge located near Ljubljana, Slovenia. The structure was widened in 1989 to accommodate pedestrians and cyclists by integrating prefabricated prestressed reinforced concrete T-girders. To assess the structural behaviour of the bridge, six girders were subjected to a rigorous testing program involving bending and shear tests in a laboratory setting. The tests were performed on girders with static lengths of 12.20 meters and 9.90 meters. The program aimed to evaluate the structural performance of the girders. Preliminary results indicate satisfactory structural behaviour of the prestressed T-girders under the applied loads, with insights into their performance under both bending and shear stresses. This study contributes valuable data for assessing the long-term behaviour of bridges. The outcomes are particularly relevant for optimising resource allocation in bridge rehabilitation projects and ensuring safety and functionality in transportation networks.
Keywords: laboratory testing, prestressed girders, assessment, load test, operational modal analysis, damage, acoustic emission
Published in DiRROS: 22.01.2026; Views: 215; Downloads: 111
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4. Challenges of implementing bridge weigh-in-motion on a century-old steel-riveted railway bridgeDoron Hekič, Mirko Kosič, Jan Kalin, Aleš Žnidarič, Andrej Anžlin, 2024, published scientific conference contribution Abstract: This study explores the challenges and methodologies involved in implementing bridge weigh-in-motion (B-WIM) system on a century-old steel riveted railway bridge. A unique aspect of this study, funded by the EU H2020 Shift2Rail Joint Undertaking, was the adaptation of B-WIM systems to the specific constraints of railway bridges since, traditionally, this technology is used to collect heavy gross vehicle loading data on road bridges. The paper details the experimental setup on an old steel-riveted railway bridge, including sensor placement and calibration processes. It highlights the complexities encountered, such as differences in bridge response due to passenger and other type of trains. It introduces the system calibration strategy using known axle loads from passenger locomotives. The study provides insights into the structural response of old steel bridges under traffic loads, contributing valuable data to the field of railway bridge monitoring and maintenance.
Keywords: bridge, B-WIM, bridge Weigh-in-Motion system, numerical model updating, bridge response measurements, railways
Published in DiRROS: 14.08.2024; Views: 1190; Downloads: 725
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5. Load testing of the first stress ribbon bridge in SloveniaĐorđe Đukić, Doron Hekič, Mirko Kosič, Rok Vezočnik, Andrej Anžlin, Andrej Štrukelj, Marjan Pipenbaher, Tomaž Weingerl, 2024, published scientific conference contribution Abstract: Paper presents selected results of the diagnostic load testing of a newly-built footbridge in Novo Mesto, Slovenia. The bridge is significant as the first bridge in Slovenia being built with the stress ribbon technology. The diagnostic load testing took place in March 2023 and comprised of three-stage static load testing, dynamic testing with a light truck driving over artificial obstacles, and measurement of ambient vibrations. The consistency between the actual response of the bridge and the response of the finite element (FE) model, used in the design, was evaluated by comparing vertical displacements from the static load testing, natural frequencies and mode shapes. The comparison of the results indicates a satisfactory agreement between the measurements and the response of the FE model, confirming the appropriateness of the employed FE model.
Keywords: bridge, bridge response measurements, stress ribon, load test
Published in DiRROS: 14.08.2024; Views: 1040; Downloads: 663
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6. 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: 1663; Downloads: 1051
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7. 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: 1536; Downloads: 865
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