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81.
Flood vulnerability study of a roadway bridge subjected to hydrodynamic actions, local scour and wood debris accumulation
Mirko Kosič, Andrej Anžlin, Valentina Bau', 2022, izvirni znanstveni članek

Povzetek: 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.
Ključne besede: flooding, vulnerability, wood debris, local scour, hydrodynamic load, stochastic approach, bridges, open access
Objavljeno v DiRROS: 31.05.2023; Ogledov: 319; Prenosov: 177
.pdf Celotno besedilo (7,59 MB)
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82.
Analysis of the response of a roadway bridge under extreme flooding-related events: Scour and debris-loading
Mirko Kosič, Luke J. Prendergast, Andrej Anžlin, 2023, izvirni znanstveni članek

Povzetek: 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.
Ključne besede: local scour, wood debris, flooding, resilience, soil-structure interaction, bridges, open access
Objavljeno v DiRROS: 29.05.2023; Ogledov: 271; Prenosov: 216
.pdf Celotno besedilo (4,32 MB)
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83.
Model updating concept using bridge Weigh-in-Motion data
Doron 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: 373; Prenosov: 196
.pdf Celotno besedilo (26,28 MB)
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84.
Obravnava urgentnih stanj
Nena Golob, Maja Ivanetič Pantar, Andrej Žist, 2023, samostojni strokovni sestavek ali poglavje v monografski publikaciji

Ključne besede: paliativna oskrba, onkologija, bolniki
Objavljeno v DiRROS: 24.05.2023; Ogledov: 293; Prenosov: 68
.pdf Celotno besedilo (126,36 KB)

85.
Obravnava driske
Nena Golob, Nežka Hribernik, Andrej Žist, 2023, samostojni strokovni sestavek ali poglavje v monografski publikaciji

Ključne besede: paliativna oskrba, onkologija, bolniki
Objavljeno v DiRROS: 24.05.2023; Ogledov: 255; Prenosov: 59
.pdf Celotno besedilo (118,08 KB)

86.
Obravnava slabosti in bruhanja
Andrej Žist, Nežka Hribernik, Maja Ebert Moltara, 2023, samostojni strokovni sestavek ali poglavje v monografski publikaciji

Ključne besede: paliativna oskrba, onkologija, bolniki
Objavljeno v DiRROS: 24.05.2023; Ogledov: 227; Prenosov: 73
.pdf Celotno besedilo (115,10 KB)

87.
Technical and radiological characterisation of fly ash and bottom ash from thermal power plant
Emilija Fidanchevski, Biljana Angjusheva, Vojo Jovanov, Pece Murtanovski, Ljubica Vladiceska, Nikolina Stamatovska Aluloska, Jelena Krneta Nikolić, Andrej Ipavec, Katarina Šter, Maruša Mrak, Sabina Dolenec, 2021, izvirni znanstveni članek

Povzetek: Huge quantities of fly ash and bottom ash are generated from thermal power plants and it presents great concern for country, mainly due to the environmental effects. In this study, fly ashes and bottom ash were characterized from technical and radiological aspects. Health effect due to the activity of radionuclides 226Ra, 232Th and 40K was estimated via radium equivalent activity (Raeq), external hazards index (Hex), the external absorbed dose rate (D) and annual effective dose rate (EDR). The specific surface area (40.25 m2 g−1), particle density (1.88 g cm−3) and LOI (23.49%) were typical for bottom ash. Siliceous fly ash contained 32% reactive silica. The annual effective dose rate for all ashes is ≤ 0.2 mSv y−1. Both, fly ash and bottom ash present potential secondary raw materials to be used for building purposes as result of their technological and radiological assessment.
Ključne besede: fly ash, bottom ash, gamma spectrometry, building materials
Objavljeno v DiRROS: 22.05.2023; Ogledov: 257; Prenosov: 116
.pdf Celotno besedilo (1009,85 KB)
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88.
Magnetic extraction of weathered tire wear particles and polyethylene microplastics
Vaibhav Budhiraja, Branka Mušič, Andrej Kržan, 2022, izvirni znanstveni članek

Povzetek: Magnetic extraction offers a rapid and low-cost solution to microplastic (MP) separation, in which we magnetize the hydrophobic surface of MPs to separate them from complex environmental matrices using magnets. We synthesized a hydrophobic Fe-silane based nanocomposite (Fe@SiO2/MDOS) to separate MPs from freshwater. Pristine and weathered, polyethylene (PE) and tire wear particles (TWP) of different sizes were used in the study. The weathering of MPs was performed in an accelerated weathering chamber according to ISO 4892-2:2013 standards that mimic natural weathering conditions. The chemical properties and morphology of the Fe@SiO2/MDOS, PE and TWP were confirmed by Fourier transform infrared spectroscopy and Scanning electron microscopy, respectively. The thermal properties of PE and TWP were evaluated by Thermogravimetric analysis. Using 1.00 mg of Fe@SiO2/MDOS nanocomposite, 2.00 mg of pristine and weathered PE were extracted from freshwater; whereas, using the same amount of the nanocomposite, 7.92 mg of pristine TWP and 6.87 mg of weathered TWP were extracted. The retrieval of weathered TWP was 13% less than that of pristine TWP, which can be attributed to the increasing hydrophilicity of weathered TWP. The results reveal that the effectiveness of the magnetic separation technique varies among different polymer types and their sizes; the weathering of MPs also influences the magnetic separation efficiency.
Ključne besede: degradation, magnetic separation, microplastics, polyethylene, tire wear particles, open access
Objavljeno v DiRROS: 03.05.2023; Ogledov: 384; Prenosov: 326
.pdf Celotno besedilo (1,97 MB)
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89.
90.
In memoriam : prof. dr. Franc Gašperšič (1932-2023)
Andrej Bončina, 2023, poljudni članek

Ključne besede: biografije
Objavljeno v DiRROS: 19.04.2023; Ogledov: 425; Prenosov: 57
.pdf Celotno besedilo (116,63 KB)

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