1. 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, izvirni znanstveni članek Povzetek: 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.
Ključne besede: bridge health monitoring, bridge WIM, structural dynamics, damage detection, vehicle-bridge interaction
Objavljeno v DiRROS: 12.09.2023; Ogledov: 52; Prenosov: 17
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2. Using bridge weigh-in-motion systems to monitor single-span bridge influence linesAleš Žnidarič, Jan Kalin, 2020, izvirni znanstveni članek Povzetek: 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.
Ključne besede: bridge loading, bridge response, temperature dependency, influence line, monitoring
Objavljeno v DiRROS: 12.09.2023; Ogledov: 66; Prenosov: 26
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3. Izgradnja lizimetrov za preučevanje izpiranja potencionalno nevarnih snovi iz gradbenih proizvodovJanez Turk, Janko Urbanc, Ana Mladenovič, Alenka Sešek Pavlin, Primož Oprčkal, Karmen Fifer Bizjak, Barbara Likar, Marko Brodnik, Nina Mali, 2020, izvirni znanstveni članek Povzetek: Z uporabo recikliranih odpadkov v gradbeništvu nadomeščamo naravne materiale in s tem vzpostavljamo krožno gospodarstvo na lokalnem nivoju. Pomemben vidik je tudi ohranjanje naravnih virov. To je še posebno pereče pri zemeljskih delih (npr. zasipih in nasipih), kjer prihaja do velike porabe materialov. Geotehnični kompoziti iz recikliranih materialov, v primerjavi z naravnimi agregati ali zemljinami, lahko vsebujejo višje celotne koncentracije potencialno nevarnih snovi (težke kovine, klorid, sulfat, fluorid, organska onesnaževala itd.). Pogoj za uporabo takšnih kompozitov je, da so v njih potencialno nevarne snovi imobilizirane in da so zato iz kemijskega vidika trajno inertni. Možni vplivi na okolje, predvsem prenos različnih potencialno nevarnih snovi iz kompozitov v tla oziroma vodonosnik, so običajno ovrednoteni na laboratorijski ravni, medtem ko je njihovo obnašanje v dejanskem okolju slabo proučeno. Zato se pojavljajo zahteve po razvoju občutljivih, zanesljivih in cenovno ter časovno učinkovitih orodij za določitev masnih tokov potencialno nevarnih snovi iz gradbenih proizvodov, na primer geotehničnih kompozitov, pod vplivi različnih okoljskih dejavnikov. V članku predstavljamo postopek vzpostavitve terenskega laboratorija na osnovi sistema "pan" lizimetrov, za zbiranje izcednih voda iz zasipov, ki so bili izdelani iz geotehničnih kompozitov iz recikliranih materialov. Lizimetre smo konstruirali in izvedli tako, da je njihova izgradnja cenovno ugodna, hkrati pa so po svojih dimenzijah dovolj veliki, da reprezentativno odražajo procese v zgrajenih geotehničnih zasipih. Pridobljeni podatki o količini in parametrih izcedne vode bodo služili kot osnova za določanje vodne bilance in za študij imobilizacije potencialno nevarnih snovi v kompozitih. Hkrati bodo uporabljeni kot vhodni podatki za geokemijski numerični model, s katerim bomo simulirali transport potencialno nevarnih snovi, sproščenih iz preučevanih kompozitov, v različnih tipih vodonosnikov (npr. medzrnski in razpoklinski).
Ključne besede: lizimeter, izlužek, okoljski monitoring, geotehnični zasip, odpadki
Objavljeno v DiRROS: 12.09.2023; Ogledov: 40; Prenosov: 15
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4. First record of the northern spruce bark beetle, Ips duplicatus (Sahlberg, 1836), in SloveniaAndreja Kavčič, Zina Devetak, Barbara Piškur, Eva Groznik, Maarten De Groot, 2023, izvirni znanstveni članek Povzetek: The northern spruce bark beetle, Ips duplicatus (Sahlberg), has invaded Central Europe in the past century and continues to spread southwards and westwards. It has caused damage in some parts of Europe in recent decades and poses a serious threat to spruce forests across the continent. From 2018 to 2021, we conducted intensive monitoring to determine the status of I. duplicatus in Slovenia. We used different types of traps and pheromone lures that attract I. duplicatus beetles and took bark samples from bark beetle-infested trees. Of the 26 traps used during the four years of monitoring, I. duplicatus was found in 16 traps in the central part of Slovenia in 2020. Adult beetles were caught in traps containing both I. typographus and I. duplicatus lures. The identity of this species was confirmed using morphological keys and molecular methods. One to five I. duplicatus beetles were found per trap, totaling 25 specimens. However, we did not confirm any I. duplicatus in samples taken from trees in 2021. We conclude that I. duplicatus is present in Slovenia, but our results suggest that the species is only present locally and that the population is small.
Ključne besede: biological invasions, forest pests, temperate forests, conifers, damage, forest pest monitoring, confirmation
Objavljeno v DiRROS: 05.09.2023; Ogledov: 59; Prenosov: 24
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6. Experiences with the National Forest Inventory (NFI) in Slovenia : presented at 3rd Meeting of the Regional Expert Advisory Working Group on Forest from the Western Balkans, 31 January–1 February 2023, in Durrës, AlbaniaMitja Skudnik, Primož Simončič, 2023, prispevek na konferenci brez natisa Ključne besede: national forest inventory, monitoring, developement of forests, national level, Slovenia
Objavljeno v DiRROS: 24.07.2023; Ogledov: 114; Prenosov: 30
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8. Poročilo o spremljanju stanja gozdov za leto 2022 : vsebinsko poročilo o spremljanju stanja gozdov v skladu s Pravilnikom o varstvu gozdov (2009)Mitja Ferlan, Andrej Grah, Janez Kermavnar, Nike Krajnc, Lado Kutnar, Nikica Ogris, Anže Martin Pintar, Matej Rupel, Mitja Skudnik, Urša Vilhar, Daniel Žlindra, 2023, končno poročilo o rezultatih raziskav Ključne besede: varstvo gozdov, monitoring, stanje gozdov, zdravstveno stanje krošenj, popis povzročiteljev poškodb, meteorološke meritve, osutost dreves, poročila, Slovenija
Objavljeno v DiRROS: 29.06.2023; Ogledov: 131; Prenosov: 110
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9. 3D finite element analysis of a concrete dam behavior under changing hydrostatic load : a case studyPavel Žvanut, 2022, izvirni znanstveni članek Povzetek: In this study, a large arch-gravity Moste Dam was analyzed, where an automated system for the measurements of horizontal displacements of the upper part of the dam was established. Two-dimensional (2D) and three-dimensional (3D) analyses of dam behavior, taking into account the earth pressures and the hydrostatic load, using the finite element method (FEM)-based computer program DIANA, were performed. The influence of lowering the water level of the reservoir by 6.2 m, on the horizontal displacements of the upper part of the dam, at stationary temperature conditions, was investigated. It was found that the results of the performed 2D and 3D FEM analyses fitted in very well with the result of experimentally determined measurement of horizontal displacements (which was 0.48 mm in the upstream direction) that was obtained using a hanging pendulum. An additional comparison of the results of 3D calculations showed that the finite element mesh density had a small effect on the calculated horizontal displacements.
Ključne besede: concrete dam, finite element method, material properties, structure behavior, measuring instruments, monitoring, ime series analysis, horizontal displacements, hydrostatic pressure
Objavljeno v DiRROS: 21.06.2023; Ogledov: 136; Prenosov: 49
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10. Model updating concept using bridge Weigh-in-Motion dataDoron Hekič, Andrej Anžlin, Maja Kreslin, Aleš Žnidarič, Peter Češarek, 2023, izvirni znanstveni članek Povzetek: 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.
Ključne besede: monitoring, bridge, viaduct, bridge weigh-in-motion (B-WIM), structural health monitoring (SHM), finite element (FE), calibration, model updating
Objavljeno v DiRROS: 29.05.2023; Ogledov: 108; Prenosov: 34
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