21. Cost-benefit analysis of fire protection in buildings : application of a present net value approachThomas Gernay, Shuna Ni, David Unobe, Andrea Lucherini, Ranjit Kumar Chaudhary, Ruben Van Coile, 2023, izvirni znanstveni članek Povzetek: In fire safety engineering, cost–benefit analysis provides a systematic method to assess whether the projected benefits from a fire safety measure outweigh its costs. However, there remains a wide discrepancy between methods used in the field for cost–benefit analysis, as well as a lack of quantitative data on the costs and economic impact of fire protection in buildings. In a recent research project, a reference methodology was proposed based on Present Net Value evaluation and on a combination of specialized construction database, fire statistics, and numerical modeling for estimation of the cost components. This paper presents the application of the methodology to four case studies. The case studies allow describing the methodology, the collection of data, fire statistics, and loss estimation, as well as illustrating how the methodology can support decision-making when multiple alternatives are compared. Under the assumptions adopted for the single-family house and the residential timber building case studies, it is found that for every 1\$, invested in sprinklers, \$1.06 is saved. This benefit–cost ratio increases with increasing valuation of indirect losses and statistical value of life. Sensitivity analyses are provided to explore the robustness of the investment recommendations. The results of evaluations, adapted from the presented case studies with project-specific inputs, can support decision making for policy makers, insurance companies, and individual building owners.
Ključne besede: fire safety, cost-benefit analysis, fire protection, fire statistics, sprinklers, compartmentation
Objavljeno v DiRROS: 29.11.2023; Ogledov: 259; Prenosov: 32
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22. Hydrothermal synthesis of rare-earth modified titania : influence on phase composition, optical properties, and photocatalytic activityNejc Rozman, David Maria Tobaldi, Uroš Cvelbar, Harinarayanan Puliyalil, Joao Antonio Labrincha, Andraž Legat, Andrijana Sever Škapin, 2019, izvirni znanstveni članek Povzetek: In order to expand the use of titania indoor as well as to increase its overall performance, narrowing the band gap is one of the possibilities to achieve this. Modifying with rare earths (REs) has been relatively unexplored, especially the modification of rutile with rare earth cations. The aim of this study was to find the influence of the modification of TiO2 with rare earths on its structural, optical, morphological, and photocatalytic properties. Titania was synthesized using TiOSO4 as the source of titanium via hydrothermal synthesis procedure at low temperature (200 °C) and modified with selected rare earth elements, namely, Ce, La, and Gd. Structural properties of samples were determined by X-ray powder diffraction (XRD), and the phase ratio was calculated using the Rietveld method. Optical properties were analyzed by ultraviolet and visible light (UV-Vis) spectroscopy. Field emission scanning electron microscope (FE-SEM) was used to determine the morphological properties of samples and to estimate the size of primary crystals. X-ray photoelectron spectroscopy (XPS) was used to determine the chemical bonding properties of samples. Photocatalytic activity of the prepared photocatalysts as well as the titania available on the market (P25) was measured in three different setups, assessing volatile organic compound (VOC) degradation, NOx abatement, and water purification. It was found out that modification with rare earth elements slows down the transformation of anatase and brookite to rutile. Whereas the unmodified sample was composed of only rutile, La- and Gd-modified samples contained anatase and rutile, and Ce-modified samples consisted of anatase, brookite, and rutile. Modification with rare earth metals has turned out to be detrimental to photocatalytic activity. In all cases, pure TiO2 outperformed the modified samples. Cerium-modified TiO2 was the least active sample, despite having a light absorption tail up to 585 nm wavelength. La- and Gd-modified samples did not show a significant shift in light absorption when compared to the pure TiO2 sample. The reason for the lower activity of modified samples was attributed to a greater Ti3+/Ti4+ ratio and a large amount of hydroxyl oxygen found in pure TiO2. All the modified samples had a smaller Ti3+/Ti4+ ratio and less hydroxyl oxygen
Ključne besede: TiO2, photocatalytic activity, rare earths, modification, visible light activity
Objavljeno v DiRROS: 22.11.2023; Ogledov: 268; Prenosov: 141
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23. The role of relative humidity on crystallization of calcium carbonate from calcium acetoacetate precursorAndreja Pondelak, Francesca Rosi, Celeste Maurich, Costanza Miliani, Srečo D. Škapin, Andrijana Sever Škapin, 2019, izvirni znanstveni članek Povzetek: Calcium acetoacetate, Ca(OAcAc)2, was exposed 7, 30 and 365 days to different values of relative humidity (33%, 48%, 75% and 96%) at 40 °C in order to study its transformation to CaCO3. The resulting Ca(OAcAc)2 decomposition and the time dependence of the phase transformations were monitored and critically evaluated by Fourier transform infrared spectroscopy, field emission scanning electron microscopy and X-ray powder diffraction. The impact of relative humidity on CaCO3 polymorph formation was thoroughly assessed. In all of the conditions used and for all ageing periods, the formed crystal structure is found to be vaterite. At the lowest relative humidity (33%), the amorphous CaCO3 remains more or less almost untransformed even after one year of exposure. It is proposed that the reason for the stability of amorphous CaCO3 is due to the limited amount of physisorbed water on the surfaces of the particles, which is considered the driving force for its transformation. However, the carbonation process is faster in the case of the highest humidity (96%). The findings are not only important for better solutions in the field of cultural heritage, but also shed new light on the fundamental mechanism of CaCO3 crystallization.
Ključne besede: calcium acetoacetate, relative humidity, carbonation, amorphous carbonate, vaterite, mechanism
Objavljeno v DiRROS: 22.11.2023; Ogledov: 316; Prenosov: 145
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24. Efficiency of novel photocatalytic coating and consolidants for protection of valuable mineral substratesAndreja Pondelak, Sabina Dolenec, Jonjaua Ranogajec, Luka Škrlep, Snezana B. Vučetić, Vilma Ducman, Andrijana Sever Škapin, 2019, izvirni znanstveni članek Povzetek: In the process of protection and consolidation of valuable materials, the efficiency is the crucial property that needs to be considered. TiO2/ZnAl layered double hydroxide (LDH) coating and silicate- and carbonate-based consolidants were synthesized and proposed to be used for protection and consolidation of four porous mineral substrates: brick, stone, render and mortar. The photocatalytic efficiency of TiO2/ZnAl LDH coating, as well as consolidation efficiency of two consolidants, both applied on model substrates, were studied. The photocatalytic coating showed significant activity and performed well after the durability tests involving rinsing and freezing/thawing procedures. After treatment with both consolidants, a serious enhancement of consolidation of the used substrates was found. On the other hand, the application of TiO2/ZnAl LDH, as well as consolidants, caused negligible changes in the water vapour permeability values and in appearance of the porous mineral substrates, indicating a high level of compatibility.
Ključne besede: photocatalytic coating, consolidant, protection, conservation, porous substrate, cultural heritage
Objavljeno v DiRROS: 21.11.2023; Ogledov: 236; Prenosov: 176
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25. Photocatalytic CO2 reduction over mesoporous TiO2 photocatalystsMartin Reli, Peter Nadrah, Miroslava Filip Edelmannová, Rudolf Ricka, Andrijana Sever Škapin, Urška Lavrenčič Štangar, Kamila Kočí, 2024, izvirni znanstveni članek Povzetek: In this study, we investigated different synthesis methods (template-free and template-based) using copolymers of poly(ethylene oxide) and poly(propylene oxide) to enhance the CO2 reduction activity of mesoporous TiO2. Our main goal was to identify key factors affecting photocatalyst efficiency and selectivity. We compared the newly synthesized TiO2 photocatalysts with the commercial photocatalyst P25. Among the materials studied, TiO2-P123 in its pure anatase form demonstrated the highest photoreduction efficiency and CO2 selectivity. In contrast, TiO2-EG, TiO2-F127, and P25, which contained both rutile and anatase phases, exhibited decreased photoactivity due to the formation of a type II heterojunction between the phases and higher oxygen adsorption on rutile's surface. Additionally, we observed that the choice of chemicals for photocatalyst preparation significantly influenced the specific surface area. TiO2-P123, the most active photocatalyst, had the highest specific surface area, providing more reactive sites for improved light absorption efficiency and prolonged electron-hole pair lifetimes, resulting in enhanced photocatalytic activity. We also calculated apparent quantum yields to support our findings.
Ključne besede: CO2 reduction, TiO2, photocatalysis, mesoporous material, Sol-gel method
Objavljeno v DiRROS: 14.11.2023; Ogledov: 357; Prenosov: 37
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26. UV light causes structural changes in microplastics exposed in bio-solidsS. S. Alavian Petroody, Seyed Hossein Hashemi, Luka Škrlep, Branka Mušič, Cornelis A. M. van Gestel, Andrijana Sever Škapin, 2023, izvirni znanstveni članek Povzetek: Bio-solids (biological sludge) from wastewater treatment plants are a significant source of the emission of microplastics (MPs) into the environment. Weakening the structure of MPs before they enter the environment may accelerate their degradation and reduce the environmental exposure time. Therefore, we studied the effect of UV-A and UV-C, applied at 70 °C, on three types of MPs, polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET), that are commonly found in sewage sludge, using three shapes (fibers, lines, granules). The MPs were exposed to UV radiation in bio-solid suspensions, and to air and water as control. The structural changes in and degradation of the MPs were investigated using Attenuated Total Reflectance–Fourier Transform Infrared Spectrometry (ATR-FTIR) and surface morphology was performed with SEM analysis. UV exposure led to the emergence of carbonyl and hydroxyl groups in all of the PP samples. In PE and PET, these groups were formed only in the bio-solid suspensions. The presence of carbonyl and hydroxyl groups increased with an increasing exposure time. Overall, UV radiation had the greatest impact on the MPs in the bio-solids suspension. Due to the surface-to-volume ratio of the tested samples, which influences the degradation rate, the fibers were more degraded than the other two plastic shapes. UV-A was slightly more effective at degrading the MPs than UV-C. These findings show that ultraviolet radiation in combination with an elevated temperature affects the structure of polymers in wastewater bio-solids, which can accelerate their degradation.
Ključne besede: microplastics, degradation, hydroxyl, carbonyl, ultraviolet light
Objavljeno v DiRROS: 14.11.2023; Ogledov: 320; Prenosov: 164
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27. Defining the fire decay and the cooling phase of post-flashover compartment firesAndrea Lucherini, Jose L. Torero, 2023, izvirni znanstveni članek Povzetek: The current research study discusses and characterises the fire decay and cooling phase of post-flashover compartment fires, as they are often mixed up despite their important heat transfer differences. The two pha- ses are defined according to the fire heat release rate time-history. The fire decay represents the phase in which the fire heat release rate decreases from the ventilation- or fuel-limited steady-state value of the fully-developed phase to fire extinguishment. This phase is highly influenced by the fuel characteristics, ranging from fast decays for hydrocarbon and liquid fuels to slow decays for charring cellulosic fuels (wood). Once the fuel is consumed, the compartment volume enters the cooling phase, where the cooling in the gas-phase and solid-phase happens with significantly different modes and characteristic times. The thermal boundary conditions at the structural elements are then defined according to physical characteristics and dynamics within the compartment. The research study also underlines how the existing performance-based methodologies lack explicit definitions of the decay and cooling phases and the corresponding thermal boundary conditions for the design of fire-safe struc- tural elements under realistic fire conditions.
Ključne besede: razpadanje ognja, hlajenje, izgorevanje, naravna izpostavljenost ognju, dinamika požara, požari v oddelkih, požarno inženirstvo, učinkovitost, požarna varnost, fire decay, cooling, burnout, natural fire exposure, fire dynamics, compartment fires, structural fire engineering, performance-based, fire safety
Objavljeno v DiRROS: 13.11.2023; Ogledov: 290; Prenosov: 139
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28. Development of multi-component fluoropolymer based coating on simulated outdoor patina on quaternary bronzeTadeja Kosec, Luka Škrlep, Erika Švara Fabjan, Andrijana Sever Škapin, Giulia Masi, Elena Bernardi, Cristina Chiavari, Claudie Josse, Jerome Esvan, Luc Robbiola, 2019, izvirni znanstveni članek Povzetek: Bronze reacts with oxygen, humidity, and pollutants in the atmosphere so that a patina forms. Natural exposure to an outdoor atmosphere can be simulated and accelerated in order to achieve a patina that mimics outdoor ancient patina. In order to avoid the uncontrolled dissolving of either the natural or artificially formed patina, protection of the patina is needed.
In this study, a multi-component fluoropolymer based coating for the protection of bronze patina was developed. In order to provide various functionalities of the coating (such as the hydrophobicity of the coating surface, obtaining interactions within the coating itself as well as a bronze substrate and inhibiting the corrosion processes), a fluoroacrylate coating with appropriate adhesion promoter was suggested, with and without a silane modified benzotriazole inhibitor. The protective efficiency and durability of the applied coatings were investigated electrochemically using potentiodynamic tests and electrochemical impedance spectroscopy in a simulated acid rain solution. All of the developed coatings showed a significant decrease in the corrosion current density. The self-assembled single layer coating (FA-MS) also showed 100% inhibition efficiency. After ageing the coating remained transparent and did not change by UV exposure and/or thermal cycling. The patina and coating investigations using FIB-SEM and EDX showed that the latter coating (FA-MS) successfully covered the surface of the patinated bronze. The mechanism of the bonding was proposed and supported with the spectroscopic observation of a thin and even coating.
Ključne besede: bronze, patina, fluoropolymer coating, atmospheric corrosion
Objavljeno v DiRROS: 25.10.2023; Ogledov: 358; Prenosov: 190
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29. Cost-benefit analysis in fire safety engineering : state-of-the-art and reference methodologyRuben Van Coile, Andrea Lucherini, Ranjit Kumar Chaudhary, Shuna Ni, David Unobe, Thomas Gernay, 2023, izvirni znanstveni članek Povzetek: Cost-effectiveness is a key consideration within fire safety engineering. Currently, different approaches are being applied in literature. These approaches differ in how cost-effectiveness is evaluated, which costs are considered, and how the preferred design solution is defined. Recognizing this issue, the Fire Protection Research Foundation enrolled an international team of researchers, supported by a broad stakeholder panel, to develop a reference methodology. In this paper, this reference methodology for cost-benefit analysis in fire safety engineering is presented following an extensive literature review. The methodology clarifies the minimum requirements for assessing cost-effectiveness, and highlights that only a present net value evaluation can be used to compare design alternatives. Commonly used cost-benefit ratios should only be used when deciding on the effectiveness of a single package of fire safety measures. An illustrative case study demonstrates the application of the meth- odology and shows how designs based on cost-benefit ratios can be sub-optimal when evaluating multiple possible fire safety measures.
Ključne besede: cost-benefit analysis, fire safety, investment, maintenance, loss, statistics, reliability
Objavljeno v DiRROS: 23.10.2023; Ogledov: 338; Prenosov: 77
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30. Deformable polyurethane joints and fibre grids for resilient seismic performance of reinforced concrete frames with orthoblock brick infillsTheodoros Rousakis, Alper Ilki, Arkadiusz Kwiecień, Alberto Viskovic, Matija Gams, Petra Triller, Bahman Ghiassi, Andrea Benedetti, Zoran Rakicevic, Camilla Colla, Omer Faruk Halici, BogusŁaw Zając, Łukasz Hojdys, Piotr Krajewski, Fabio Rizzo, Vachan Vanian, Anastasios Sapalidis, Efthimia Papadouli, Aleksandra Bogdanovic, 2020, izvirni znanstveni članek Povzetek: The behaviour of reinforced concrete frames with masonry wall infills is influenced a lot by the stiffness and strength difference between the frame and the infill, causing early detrimental damage to the infill or to the critical concrete columns. The paper reports the results from shake table seismic tests on a full-scale reinforced concrete (RC) frame building with modified hollow clay block (orthoblock brick) infill walls, within INMASPOL SERA Horizon 2020 project. The building received innovative resilient protection using Polyurethane Flexible Joints (PUFJs) made of polyurethane resin (PU), applied at the frame-infill interface in different schemes. Further, PUs were used for bonding of glass fibre grids to the weak masonry substrate to form Fibre Reinforced Polyurethanes (FRPUs) as an emergency repair intervention. The test results showed enhancement in the in-plane and out-of-plane infill performance under seismic excitations. The results confirmed remarkable delay of significant infill damages at very high RC frame inter-story drifts as a consequence of the use of PUFJs. Further, the PUFJ protection enabled the resilient repair of the infill even after very high inter-story drift of the structure up to 3.7%. The applied glass FRPU system efficiently protected the damaged infills against collapse under out-of-plane excitation while they restored large part of their in-plane stiffness.
Ključne besede: polyurethane, flexible joint, RC column, brick infill, shake table, resilience
Objavljeno v DiRROS: 05.09.2023; Ogledov: 295; Prenosov: 123
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