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: 217; Downloads: 111
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4. A practical method to incorporate scour hole shape effects in Winkler-type pile foundation models for bridgesMirko Kosič, Luke J. Prendergast, Andrej Anžlin, 2025, original scientific article Abstract: Scour erosion continues to cause significant issues for the stability and lifespan of bridges worldwide. In Slovenia, extreme flooding in 2023 caused the collapse or failure of many bridges, primarily due to scour, which was exacerbated by debris accumulation. Despite advances in predicting and monitoring scour, it remains among the top reasons for the failure of bridges during flooding. Recent advances in vibration-based health monitoring suggest that scour erosion can be detected using methods such as changes in natural frequency, mode shapes, flexibility-based deflection, and other approaches using offline sensors such as passing vehicle responses. Many of these methods have been trialled numerically where scour is implemented as a reduction in the soil level (or stiffness) around a given bridge foundation. The most common way to model scour is to lower the soil level around a foundation, however, this ignores any contribution that the scour hole shape makes to the stiffness and strength of the soil beneath the scour hole. This paper investigates how the shape of scour holes influences the stiffness and strength of the remaining soil to understand the impact on the modal behaviour of a bridge. A numerical model of a bridge is developed where scour is implemented by removing Winkler springs from the model, and different scour hole shapes are considered in terms of how the remaining overburden influences the stiffness and strength of the soil springs. Scour hole shape properties are considered by means of varying the depth, width, and slope angle of the hole around a given foundation element. For the analyses in this paper, different scour hole shapes are implemented on an example bridge corresponding to local scour holes with narrow width; wider local scour holes; and general scour, where the full soil layer is removed (infinite width). The changes in the modal periods and mode shapes of the bridge in the traffic and river flow directions are assessed to understand the impact of the different scour types on the vibration characteristics.
Keywords: scour, dynamics, overburden, frequency, damage, bridges, scour hole shape
Published in DiRROS: 13.01.2026; Views: 147; Downloads: 104
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5. 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: 1193; Downloads: 727
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6. 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: 664
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7. oVERFLOw project : Vulnerability assessment of embankments and bridges exposed to flooding hazards : Deliverable 6.4Valentina Bau', Mirko Kosič, Andrej Anžlin, Mario Bacic, 2022, final research report Abstract: This deliverable is a report on the development of a strategy for adaptation measures to flood events for the embankments, riverbanks and bridges, which can afterwards be used for the case study areas considered in the Overflow project. The deliverable presents a comprehensive approach that enables the choice of the best adaptation measures to overcome the vulnerability of critical infrastructure to flooding events. The most suitable countermeasures can therefore be selected based on the outcomes of the vulnerability assessment and risk forecasting tool. Such a strategy will be essential for the relevant authorities and IMs. The strategy proposes optimal adaptation measures depending on areas specificities, incorporating socio-economic and environmental multi-objective optimization.
Keywords: adaptation measures, countermeasures, vulnerability, flooding, resilience, embankments, bridges
Published in DiRROS: 29.07.2024; Views: 1184; Downloads: 442
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8. Risk based life-cycle planning for flood-resilient critical infrastructureSandra Škarić Palić, I. Stipanovic, E. Ganic, Mirko Kosič, Andrej Anžlin, M. Bacic, M. S. Kovacevic, K. Gavin, 2023, published scientific conference contribution Abstract: The paper presents a risk assessment model, developed in the project oVER-FLOw and further implemented in the project CROSScade, for determining the direct and indirect impacts of flooding hazards. As a consequence of flooding, transport infrastructure and flood protection systems can be significantly damaged and cause cascading effects on other infrastructure. To achieve flood resilient infrastructure, it is necessary to assess the vulnerability of critical assets in the affected area. The model uses novel vulnerability assessment methods for embankments and bridges exposed to different flood hazard scenarios allowing the asset owners to understand risk and performance of their infrastructure. Scarce financial resources are allocated on the critical assets allowing significant cost savings and avoiding the waste of non-renewable resources in strengthening large sections which have sufficient resilience. The consequence analysis is based on an improved quantification model for direct and indirect impacts of different flood hazard scenarios used for risk mapping of the affected area.
Keywords: flooding, risk assessment, critical infrastructure, economic loss
Published in DiRROS: 23.05.2024; Views: 1320; Downloads: 753
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9. Flood vulnerability study of a roadway bridge subjected to hydrodynamic actions, local scour and wood debris accumulationMirko Kosič, Andrej Anžlin, Valentina Bau', 2022, original scientific article Abstract: The increased occurrence and intensity of flooding events have represented a real threat to bridge reliability and end-user safety. As flood vulnerability assessment is a valuable tool for enhancing the resilience of bridges to climate change, it is of interest to push the development of such methods. To this end, a computationally efficient methodology to assess the flood vulnerability of a bridge was developed and implemented in a case study. A particular focus was devoted to modelling wood debris loads on the bridge pier, for which two different approaches were implemented. The first is a standards-based approach, whereas the second is based on up-to-date research data. The results indicate that the second approach is less conservative as it leads up to a 40% higher exceedance probability for the considered limit states. The interaction between wood debris loads and local scour was also examined and proved to have a relevant impact on the vulnerability of the bridge. These results highlight the shortcomings of the existing standards in providing accurate results. It is perceived that not only will the new quantitative tool be valuable in ensuring optimal bridge design, but it will also be beneficial for assessing bridge risk mitigation measures.
Keywords: flooding, vulnerability, wood debris, local scour, hydrodynamic load, stochastic approach, bridges, open access
Published in DiRROS: 31.05.2023; Views: 1760; Downloads: 921
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10. Analysis of the response of a roadway bridge under extreme flooding-related events: Scour and debris-loadingMirko Kosič, Luke J. Prendergast, Andrej Anžlin, 2023, original scientific article Abstract: Hydraulic actions on bridges are a leading cause of failure, especially due to the occurrence of scour erosion. Due to climate change, flooding and scour risks are exacerbating for bridges worldwide, leading to a significant stress burden on asset management agencies. Assessing structures for scour has received significant attention in recent years, however, there are few studies which investigate the influence of scour on the components of a bridge to understand how various elements interact. Moreover, the presence of debris loading, which can occur due to flooding causing debris to become lodged at structures, has not received significant attention. Debris can worsen scour conditions and increase hydraulic loading on a bridge. In this paper, an analysis of the response of various components of a roadway bridge when exposed to extreme flooding is conducted. The influence of scour and debris on hydraulic loading, internal forces, modal periods, and utilization ratios of various bridge components is ascertained. A numerical model is developed using OpenSees employing two different methods to model the soil-structure interaction. Results for several flooding scenarios show how the various bridge elements are influenced by variations in water height and velocity, scour depth, and presence of debris.
Keywords: local scour, wood debris, flooding, resilience, soil-structure interaction, bridges, open access
Published in DiRROS: 29.05.2023; Views: 1531; Downloads: 1181
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