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: 29; Downloads: 51
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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: 328; Downloads: 272
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3. Vehicle–bridge interaction modelling using precise 3D road surface analysisMaja Kreslin, Peter Češarek, Aleš Žnidarič, Darko Kokot, Jan Kalin, Rok Vezočnik, 2024, original scientific article Abstract: Uneven road surfaces are the primary source of excitation in the dynamic interaction between a bridge and a vehicle and can lead to errors in bridge weigh-in-motion (B-WIM) systems. In order to correctly reproduce this interaction in a numerical model of a bridge, it is essential to know the magnitude and location of the various roadway irregularities. This paper presents a methodology for measuring the 3D road surface using static terrestrial laser scanning and a numerical model for simulating vehicle passage over a bridge with a measured road surface. This model allows the evaluation of strain responses in the time domain at any bridge location considering different parameters such as vehicle type, lateral position and speed, road surface unevenness, bridge type, etc. Since the time domain strains are crucial for B-WIM algorithms, the proposed approach facilitates the analysis of the different factors affecting the B-WIM results. The first validation of the proposed methodology was carried out on a real bridge, where extensive measurements were performed using different sensors, including measurements of the road surface, the response of the bridge when crossed by a test vehicle and the dynamic properties of the bridge and vehicle. The comparison between the simulated and measured bridge response marks a promising step towards investigating the influence of unevenness on the results of B-WIM. Keywords: interakcija vozilo in most, terestično lasersko skeniranje, neravnost vozišča, numerično modeliranje Published in DiRROS: 26.01.2024; Views: 503; Downloads: 198
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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: 525; Downloads: 243
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5. Znanje, ki pušča sled : sedemdeset let Zavoda za gradbeništvo Slovenije 1949-20192019, professional monograph Abstract: V publikaciji je predstavljen Zavod za gradbeništvo Slovenije, ob 70-letnici. V osmih poglavjih je predstavljeno znanstveno-raziskovalno in strokovno delo. V nadaljevanju sledijo poglavja, ki predstavljajo posamezne zanszveno-raziskovalne laboratorije in strokovne službe. Keywords: Zavod za gradbeništvo Slovenije, ZAG Ljubljana, gradbeništvo, znanstveno-raziskovalna dejavnost, strokovna dejavnost, laboratoriji, predstavitev, 70 let, sedemdeset let, grajeno okolje, digitalizacija, gradnja, les, krožno gospodarstvo, napredni materiali v gradbeništvu, potresi, stavbe, trajnostna gradnja, bivanje, ekologija, voda, zrak, zemlja Published in DiRROS: 19.01.2024; Views: 390; Downloads: 314
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6. Knowledge that leaves a mark : seventy years of the Slovenian National Building and Civil Engineering Institute 1949-20192019, professional monograph Abstract: V publikaciji je predstavljen Zavod za gradbeništvo Slovenije ob 70-letnici. V osmih poglavjih je predstavljeno znanstveno-raziskovalno in strokovno delo. V nadaljevanju sledijo poglavja, ki predstavljajo posamezne znanstveno-raziskovalne laboratorije in strokovne službe. Keywords: Zavod za gradbeništvo Slovenije, ZAG Ljubljana, gradbeništvo, znanstveno-raziskovalna dejavnost, strokovna dejavnost, laboratoriji, predstavitev, 70 let, sedemdeset let, grajeno okolje, digitalizacija, gradnja, les, krožno gospodarstvo, napredni materiali v gradbeništvu, potresi, stavbe, trajnostna gradnja, bivanje, ekologija, voda, zrak, zemlja Published in DiRROS: 19.01.2024; Views: 405; Downloads: 248
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7. Uporaba sistemov za tehtanje vozil med vožnjo za določitev realne konstrukcijske varnosti mostovAleš Žnidarič, Maja Kreslin, Jan Kalin, Andrej Anžlin, 2019, original scientific article Abstract: Optimalno upravljanje mostov, ki vključuje stroške vzdrževanja, potencialna tveganja in vzdrževanje funkcionalnosti, zahteva natančne informacije o stanju konstrukcij. Eden od ključnih kazalnikov obnašanja je konstrukcijska varnost mostu, ki zahteva poglobljeno poznavanje prometnih obremenitev in njegove odpornosti proti obremenitvam. Vrednotenje varnosti je predvsem ključno za stare mostove, ki so poškodovani in se bližajo koncu življenjskega cikla. Varnost takšnih mostov z uporabo tradicionalnih računskih metod pogosto težko dokažemo. Da bi se izognili nepotrebnim ukrepom, kot je ojačitev ali celo zamenjava mostu, je priporočljivo narediti celovito analizo, ki vključuje preiskave materialov in meritve obnašanja mostu pod prometno obtežbo. Prispevek predstavlja tehnologijo tehtanja vozil med vožnjo v prostem prometnem toku na mostovih (angl. bridge weigh-in-motion oz. B-WIM), ki lahko učinkovito izmeri parametre obnašanja mostu, ki so ključni za določitev njihove realne varnosti: osne obremenitve in medosne razdalje vozil ter vplivnice, faktorje porazdelitve obtežbe in dinamični odziv konstrukcije. Poznavanje pravih vrednosti teh parametrov zmanjšuje negotovosti, povezane z obremenitvami in odzivom konstrukcije. Poleg tega lahko zaradi večje zanesljivosti izmerjenih parametrov v analizah zmanjšamo varnostne faktorje. To omogoča bolj optimalno vzdrževanje in uporabo infrastrukture ter racionalnejšo uporabo razpoložljivih finančnih sredstev. Keywords: upravljanje mostov, konstrukcijska varnost, odziv na prometno obtežbo, tehtanja vozil med vožnjo, prosti prometni tok na mostovih Published in DiRROS: 04.12.2023; Views: 515; Downloads: 216
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8. 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: 428; Downloads: 176
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9. 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: 580; Downloads: 241
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10. Using bridge weigh-in-motion systems to monitor single-span bridge influence linesAleš Žnidarič, Jan Kalin, 2020, original scientific article Abstract: Bridge weigh-in-motion systems use instrumented bridges or culverts to weigh vehicles as they pass over the structures. They also provide data to allow the calculation of several bridge performance indicators. The article starts with the basics of a bridge weigh-in-motion system and briefly describes two key bridge performance indicators, girder distribution factor and dynamic amplification factor, which are also derived from B-WIM measurements. The central part of the article focuses on monitoring of influence lines, the third key parameter that characterises the bridge performance under traffic loads. First, the method of calculating the bending moment influence lines from random heavy traffic is described. A coefficient of rotational stiffness is introduced, which defines the shape of influence lines around the supports as a linear combination of the ideal simply supported and fixed supported influence lines, to allow quantifying the influence line changes. Then the long-term monitoring of influence lines is investigated on four different single-span test bridges. The initial focus is given on the examination of the effect of temperature on the shape of influence lines. Finally, two sets of influence lines are compared on one test bridge, one from before and the other from after replacing the expansion joints and bearings. The work done so far confirms that calculating of influence lines from random vehicles with a B-WIM system is entirely feasible and that differences in their shape can be detected on single-span bridges. What remains to be investigated is the comparison of these differences to the actual damages and under which circumstances the proposed procedure can compete with or better the routine bridge inspection and the conventional monitoring techniques. Keywords: bridge loading, bridge response, temperature dependency, influence line, monitoring Published in DiRROS: 12.09.2023; Views: 654; Downloads: 254
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