1. 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: 8; Downloads: 5
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2. Modelling of traffic load effects in the assessment of existing road bridgesDominik Skokandić, Ana Mandić Ivanković, Aleš Žnidarič, Mladen Srbić, 2019, review article Abstract: Traffic load models used for the design of new bridges are based on conservative assumptions and have not been proven efficient for assessing safety of existing bridges. In the case of existing bridges, it is reasonable to use load models that are based on bridge weigh-in-motion data which, in addition to axle loads and spacing of bridge-crossing vehicles, provide information on bridge behaviour under traffic load. This paper provides an overview of traffic load models, as well as guidelines on the use of weigh-in-motion data when assessing condition of existing road bridges. Keywords: prometna obtežba, tehtanje vozil med vožnjo, mostni WIM, ocenjevanje stanja, obstoječi mostovi, traffic load, weigh-in-motion, bridge WIM, condition assessment, existing bridges Published in DiRROS: 27.03.2024; Views: 321; Downloads: 266
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3. 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: 520; Downloads: 237
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4. Določitev karakterističnih notranjih statičnih količin cestnih mostov iz podatkov tehtanja vozil med vožnjoAleš Žnidarič, Goran Turk, Maja Kreslin, 2022, original scientific article Abstract: Prispevek obravnava določitev notranjih statičnih količin cestnih mostov iz podatkov tehtanj vozil med vožnjo (meritev WIM, ang. weigh-in-motion), ki edina zagotovijo celovito in nepristransko sliko o tovornem prometu na merjenem cestnem odseku. Tovrstni podatki so ključni za določitev realnih učinkov prometnih obtežb, s katerimi dokazujemo zadostno varnost mostov, tudi starih in poškodovanih. Takšne mostove bi bilo treba ob upoštevanju obtežnih shem iz sodobnih pravilnikov za mostove pogo- sto zapreti ali jim omejiti prometno obtežbo. Predstavljene so metode, s katerimi iz podatkov WIM izračunamo karakteristične vrednosti notranjih statičnih količin. Posebej smo analizirali metodo konvolucije in rezultate primerjali z rezultati ekstrapolacije ekstremnih vrednosti, najbolj pogostega postopka za napovedovanje maksimalnih pričakovanih vplivov prometa v izbranem obdobju, ter rezultati obsežnih numeričnih simulacij. Veliko pozornost smo namenili izbiri vhodnih parametrov ter načinu od- čitavanja karakterističnih vrednosti, ki bistveno vplivajo na rezultate ekstrapolacij in simulacij. Rezultati kažejo, da daje metoda konvolucije, ki je računsko neprimerno manj zahtevna od ostalih uporabljanih metod, primerljive rezultate. Sočasno so le-ti manj občutljivi za subjektivno izbiro uporabljenih parametrov. Bistveni zaključek analize je tudi, da za zanesljiv račun karakte- rističnih notranjih statičnih količin mostov zaradi prometa potrebujemo s sistemom WIM izmerjene osne pritiske in medosne razdalje vsaj 100.000 tovornih vozil. Keywords: most, tehtanje vozil med vožnjo, notranje statične količine, konvolucija, simulacija, WIM, B-WIM Published in DiRROS: 04.12.2023; Views: 418; Downloads: 168
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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: 567; Downloads: 234
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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: 602; Downloads: 299
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7. Development and testing of a railway bridge weigh-in-motion systemDonya Hajializadeh, Aleš Žnidarič, Jan Kalin, Eugene J. OBrien, 2020, original scientific article Abstract: This study describes the development and testing of a railway bridge weigh-in-motion (RB-WIM) system. The traditional bridge WIM (B-WIM) system developed for road bridges was extended here to calculate the weights of railway carriages. The system was tested using the measured response from a test bridge in Poland, and the accuracy of the system was assessed using statically-weighed trains. To accommodate variable velocity of the trains, the standard B-WIM algorithm, which assumes a constant velocity during the passage of a vehicle, was adjusted and the algorithm revised accordingly. The results showed that the vast majority of the calculated carriage weights fell within %5% of their true, statically-weighed values. The sensitivity of the method to the calibration methods was then assessed using regression models, trained by di%erent combinations of calibration trains. Keywords: bridge weigh-in-motion, railway bridge loading, bridge instrumentation, B-WIM Published in DiRROS: 22.05.2023; Views: 494; Downloads: 245
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