1. 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: 233; Downloads: 95
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2. 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: 247; Downloads: 114
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3. 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: 252; Downloads: 96
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4. 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: 354; Downloads: 137
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5. Measurements of bridge dynamic amplification factor using bridge weigh-in-motion dataJan Kalin, Aleš Žnidarič, Andrej Anžlin, Maja Kreslin, 2022, original scientific article Abstract: The dynamic component of bridge traffic loading is commonly taken into account with a Dynamic Amplification Factor (DAF)—the ratio between the dynamic and static load effects on a bridge. In the design codes, this factor is generally more conservative than in reality. Recently a new method of cal- culation of this factor had been developed. Data from 15 different bridges have been analysed since then and this paper presents the results of the analyses. The background for Bridge Weigh-in-Motion is given, and the most recent method for DAF calculation is described. The sites from which the data originated are presented, and the selection of data discussed. The results of the analyses are presented and discussed and some examples of DAF calculations are shown. Data from the considered sites have invariably demonstrated a DAF decrease with increasing axle load. This is a significant result, especially for assessment of existing structures, since it is beneficial to use measured structural param- eters to optimise structural analysis.
Keywords: bridge loads, bridge weigh-in-motion, dynamic amplication factor, dynamic analysis, measurement, traffic loading
Published in DiRROS: 14.07.2023; Views: 299; Downloads: 158
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6. 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: 306; Downloads: 152
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