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1
Lie, T. T., i V. K. R. Kodur. "Thermal and mechanical properties of steel-fibre-reinforced concrete at elevated temperatures". Canadian Journal of Civil Engineering 23, nr 2 (1.04.1996): 511–17. http://dx.doi.org/10.1139/l96-055.
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For use in fire resistance calculations, the relevant thermal and mechanical properties of steel-fibre-reinforced concrete at elevated temperatures were determined. These properties included the thermal conductivity, specific heat, thermal expansion, and mass loss, as well as the strength and deformation properties of steel-fibre-reinforced siliceous and carbonate aggregate concretes. The thermal properties are presented in equations that express the values of these properties as a function of temperature in the temperature range between 0 °C and 1000 °C. The mechanical properties are given in the form of stress–strain relationships for the concretes at elevated temperatures. The results indicate that the steel fibres have little influence on the thermal properties of the concretes. The influence on the mechanical properties, however, is relatively greater than the influence on the thermal properties and is expected to be beneficial to the fire resistance of structural elements constructed of fibre-reinforced concrete. Key words: steel fibre, reinforced concrete, thermal properties, mechanical properties, fire resistance.
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Anderson, Stuart A. J., i Wendy R. Anderson. "Predicting the elevated dead fine fuel moisture content in gorse (Ulex europaeus L.) shrub fuels". Canadian Journal of Forest Research 39, nr 12 (grudzień 2009): 2355–68. http://dx.doi.org/10.1139/x09-142.
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Methods were developed to predict the moisture content of the elevated dead fine fuel layer in gorse ( Ulex europaeus L.) shrub fuels. This layer has been observed to be important for fire development and spread in these fuels. The accuracy of the Fine Fuel Moisture Code (FFMC) of the Canadian Fire Weather Index System to predict the moisture content of this layer was evaluated. An existing model was used to determine the response time and equilibrium moisture content from field data. This response time was incorporated into a bookkeeping model, combining the FFMC and this response time–equilibrium moisture content model. The FFMC poorly predicted the elevated dead fuel moisture content in gorse fuels, and attempts to improve its accuracy through regression modelling were unsuccessful. The response time of the elevated dead fine fuel layer was very fast (38–77 min) and has important implications for fire danger rating. The bookkeeping approach was the most promising method to predict elevated dead fuel moisture content. A limitation was the inability to model fuel-level meteorology. However, this model warrants further validation and extension to other shrub fuels and could be incorporated into existing fire danger rating systems that can utilize hourly weather data.
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Anderson, Stuart A. J., i Wendy R. Anderson. "Ignition and fire spread thresholds in gorse (Ulex europaeus)". International Journal of Wildland Fire 19, nr 5 (2010): 589. http://dx.doi.org/10.1071/wf09008.
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Field experiments were carried out in stands of gorse (Ulex europaeus L.) in New Zealand to determine the conditions under which fires would both ignite and spread. Research and operational experience in shrub fuels suggest that there is a clear difference between conditions that support ignition only (fuel ignites but does not spread beyond a single bush or clump) and conditions that are conducive to fire spread (fuel ignites and develops into a spreading fire). It is important for fire management agencies to be equipped with knowledge of these thresholds, because the different conditions require different levels of preparedness and response. Results indicate that the major variable influencing both fire ignition and fire spread development in gorse is the moisture content of the elevated dead fine fuel layer. Fires were observed to spread successfully in this elevated fuel layer only, independently of the surface fuels and the near-surface fuels. Elevated dead fuels failed to ignite at a moisture content of greater than 36%, and ignition only resulted in a spreading fire at moisture contents below 19%. The results correlate well with field observations and fire practitioners’ experience in these fuels, and provide reliable guidelines for fire management planning.
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Bamigboye, Gideon, Ben Ngene, Omotolani Aladesuru, Oluwaseun Mark, Dunmininu Adegoke i Kayode Jolayemi. "Compressive Behaviour of Coconut Fibre (Cocos nucifera) Reinforced Concrete at Elevated Temperatures". Fibers 8, nr 1 (1.01.2020): 5. http://dx.doi.org/10.3390/fib8010005.
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Fire outbreaks in buildings have been a major concern in the world today. The integrity of concrete is usually questioned due to the fact that after these fire outbreaks the strength of the concrete is reduced considerably. Various methods have been adopted to improve the fire resistance property of concrete. This study focused on the use of coconut fibre to achieve this feat. In this study, varying percentages of treated and untreated coconut fibres were incorporated into concrete and the compressive strength was tested for both before heating and after heating. The percentages of replacement were 0.25, 0.5, 0.75 and 1% fibre content by weight of cement. Concrete cubes that had 0% fibre served as control specimens. After subjecting these concrete cubes to 250 °C and 150 °C for a period of 2 h, the compressive strength increased when compared to the control. The compressive strength increased up to 0.5% replacement by 3.88%. Beyond 0.5% fibre, the compressive strength reduced. Concrete having coconut fibre that had been treated with water also exhibited the highest compressive strength of 28.71 N/mm². It is concluded that coconut fibres are a great material in improving the strength of concrete, even after it was exposed to a certain degree of elevated temperature.
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Horn, Gavin P., Julien Chaussidon, Mark Obstalecki, Daniel A. Martin, Peter Kurath, Robert G. Backstrom i Stephen Kerber. "Evaluating Fire Service Escape Ropes at Elevated Temperatures and Fire Conditions". Fire Technology 51, nr 1 (24.11.2013): 153–71. http://dx.doi.org/10.1007/s10694-013-0373-2.
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Kodur, Venkatesh. "Properties of Concrete at Elevated Temperatures". ISRN Civil Engineering 2014 (13.03.2014): 1–15. http://dx.doi.org/10.1155/2014/468510.
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Fire response of concrete structural members is dependent on the thermal, mechanical, and deformation properties of concrete. These properties vary significantly with temperature and also depend on the composition and characteristics of concrete batch mix as well as heating rate and other environmental conditions. In this chapter, the key characteristics of concrete are outlined. The various properties that influence fire resistance performance, together with the role of these properties on fire resistance, are discussed. The variation of thermal, mechanical, deformation, and spalling properties with temperature for different types of concrete are presented.
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Li, Yadong, Rongchun Wan, Xing Wang, Hui Zhao i Xun Gong. "Effects of Nb on Elevated-Temperature Properties of Fire-Resistant Steel". Crystals 12, nr 12 (16.12.2022): 1842. http://dx.doi.org/10.3390/cryst12121842.
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Objective: Two kinds of fire-resistant steel with different Nb content (Nb-free and 0.03 wt.%) were prepared for studying the effects of Nb addition on the elevated-temperature strength of fire-resistant steel. Methods: Two stages of heat treatment were carried out on the steels to obtain different microstructures. Typical microstructures, dislocation, and precipitates morphology of steels were observed by SEM and TEM. The dislocation density was calculated by the X-ray data from the microstructures. High temperature and room temperature mechanical properties of steels were determined by tensile testing. Results: The results showed that the YS of N2-HR steel (addition of 0.03 wt.% Nb) at RT and 600 °C was higher than N1-HR steel (Nb-free) by about 81 and 30 MPa, respectively. This indicates that Nb is an alloying element as effective as Mo in increasing the elevated-temperature strength of fire-resistant steel. The dominant strengthening mechanisms of Nb addition on elevated-temperature yield strength are precipitation strengthening and bainite strengthening. Conclusions: Theoretical analysis shows that there are two precipitation strengthening stages in fire-resistant steel: (1) increasing dislocation density during hot rolling, and (2) blocking dislocation movement and recovery in tensile testing. The results also show that the effect of fine grain strengthening is not obvious at high temperature, but is obvious at room temperature.
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Wan, Rong Chun, Feng Sun, Lan Ting Zhang i Ai Dang Shan. "Study on Microstructure and Properties of Low-Mo Fire-Resistant Steel". Advanced Materials Research 168-170 (grudzień 2010): 1792–95. http://dx.doi.org/10.4028/www.scientific.net/amr.168-170.1792.
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The number of steel-frame buildings is increasing as a result of development of social economy. However, the fire-resistant property of steel-frame buildings is much weaker than that of brick-frame buildings and RC-frame buildings. In response to such demand, fire-resistant steel has been developed since the last two decades. Mo is one of the most effective strengthening elements for the high-temperature strength of steels. With the increase of the Mo content in steels, there is a dramatic increase in costs which is unacceptable for the cost-sensitive construction area. Therefore, a fire-resistant steel with a low Mo content is highly desired. Two fire-resistant steels with low Mo content (<0.3%) were designed in this paper. The interdependence of microstructure, properties and temperature was studied and analyzed in hot-rolled testing steels. The results show that the low-Mo fire-resistant steels have improved elevated temperature strength (The yield strength of Nb content steel is 240MPa, which can met the requirements of grade Q345 fire-resistant steel), low yield ratio (<0.6) and good welding performance (Ceq≈0.40). The bainite and fine grains are mainly beneficial to the elevated temperature UTS. Nb is an alloying element effective in increasing elevated temperature strength (especially for YS) as well as Mo.
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Abubakr, Ahmed, i Ahmed Soliman. "Impact Behaviour of Steel-Fibre-Reinforced Alkali-Activated Slag Concrete Exposed to Elevated Temperatures". Materials 16, nr 11 (31.05.2023): 4096. http://dx.doi.org/10.3390/ma16114096.
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Concrete protective structures are mainly meant to withstand impact loads. However, fire events weaken concrete and reduce its impact resistance. This study investigated the impact behaviour of steel-fibre-reinforced alkali-activated slag (AAS) concrete before and after exposure to elevated temperatures (i.e., 200 °C, 400 °C, and 600 °C). Hydration products’ stability under elevated temperatures, their effects on the fibre–matrix bond, and, consequently, AAS’s static and dynamic responses were investigated. The results reveal that adopting the performance-based design concept to achieve a balance between AAS mixtures’ performance under ambient and elevated temperatures is a crucial designing aspect. Advancing hydration products’ formation will increase the fibre–matrix bond at ambient temperature while negatively affecting it at elevated temperatures. High amounts of formed and, eventually, decomposed hydration products at elevated temperatures reduced the residual strength due to lowering the fibre–matrix bond and developing internal micro-cracks. Steel fibre’s role in reinforcing the hydrostatic core formed during impact loads and delaying crack initiation was emphasized. These findings highlight the need to integrate material and structure design to achieve optimum performance and that low-grade materials can be desired based on the targeted performance. A set of empirical equations for the correlation between steel fibre content in the AAS mixture and corresponding impact performance before and after fire exposure was provided and verified.
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Liu, Shuai. "Failure Temperatures of Unprotected Composite Cellular Beams at Elevated Temperatures". Applied Mechanics and Materials 638-640 (wrzesień 2014): 2006–9. http://dx.doi.org/10.4028/www.scientific.net/amm.638-640.2006.
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Failure temperatures of composite cellular beams subject to a standard fire condition were investigated thoroughly by the Finite Element Method. A finite element model was developed for the fire performance analysis of composite cellular beams. Practical design guidance on the fire design of composite cellular beams is presented concerning the failure temperature.
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Kakali, G., R. Leventi, V. Benekis i S. Tsivilis. "Behavior of blended cement pastes at elevated temperature". Chemical Industry and Chemical Engineering Quarterly 12, nr 2 (2006): 133–36. http://dx.doi.org/10.2298/ciceq0602133k.
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Fire can cause severe damage to building structures. This fact has increased the importance of the fire resistance of concrete. The consideration of the fire resistance of concrete requires the complete knowledge of the behaviour of each concrete component under elevated temperatures. The resistance of blended cement pastes upon heating was studied in the present paper. Natural pozzolana, fly ash, ground granulated blast-furnace slag, metakaolin and limestone were used as the main cement constituents. Blended cements were prepared by replacing a part of Portland Cement (PC) with the minerals mentioned above (10% w/w in the case of metakaolin, 20% w/w in the case of the rest materials). The specimens were water-cured for 3 months and then they were thermally treated at 200, 400, 600 800 and 1000?C for 1h. Visual inspection, mass measurements and ultrasonic pulse velocity measurements were carried out after each thermal treatment. It was concluded that the cohesion of the pastes was strongly affected by the kind of the main constituent, added to the Portland cement. The use of pozzolanic materials and especially metakaolin improved the fire resistance of the pastes, while the samples with limestone show the worst behavior.
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Elkady, H., i A. Hasan. "Protection of reinforced concrete beams retrofitted by carbon fibre-reinforced polymer composites against elevated temperatures". Canadian Journal of Civil Engineering 37, nr 9 (wrzesień 2010): 1171–78. http://dx.doi.org/10.1139/l10-059.
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This paper presents the outcome of the first part of a 3 year project aiming to investigate the effect of elevated temperatures on carbon fibre-reinforced polymer (CFRP) retrofitted structures. Accordingly, different protecting mixes to be used as thermal insulating covers were proposed and evaluated. This experimental program addresses a series of indirect fire tests on reinforced concrete beams retrofitted with CFRP laminates exposed to a temperature of 900 °C (1652 °F) after being protected with ten types of special mortar covers. Materials known for their low coefficient of thermal conductivity were added in certain ratios to form mortars for these protective covers. Tests were carried out in a test furnace designed to produce the standard temperature–time curve specified in ASTM E119–95a. Scale effect was considered by proper adjustment of the exposure time to fire test. Temperature at the CFRP level, just below the protecting covers, was monitored to determine the efficiency of the covers in reducing heat transfer during the fire test. Furthermore, mechanical bending load tests were performed on specimens before and after fire tests to determine reduction in flexure failure load of the specimens due to indirect fire exposure. This reduction was found to vary from 10% to 48% for different tested coatings. In spite of the high damage in the protection covers expressing the lowest performance, reinforced concrete beams were still unaffected and could be restrengthened to return to their original status. Recommendations showing proper thicknesses of application and necessary precautions to be taken when using CFRP in retrofitting reinforced concrete structures to enhance their fire resistance were presented.
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Zeinoddini, M., S. A. Hosseini, M. Daghigh i S. Arnavaz. "Structural Post-Fire Behaviour of the Steel I-Shape Beams-to-Cylindrical Columns". Applied Mechanics and Materials 249-250 (grudzień 2012): 1057–62. http://dx.doi.org/10.4028/www.scientific.net/amm.249-250.1057.
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Previous researchers have tried to predict the response of different types of structures under elevated temperatures. The results are important in preventing the collapse of buildings in fire. Post-fire status of the structures is also of interest for ensuring the safety of rescue workers during the fire and in the post-fire situations. Determining the extent of the structural damage left behind a fire event is necessary to draw up adequate repair plans. Connections play an important role on the fire performance of different structures. Due to the high cost of fire tests, adequate experimental data about a broad range of connections is not available. A vulnerable type of such connections to fire is the weld connections between I-shape beams and cylindrical columns in oil platform topsides. Considering the high probability of fire in oil platforms, study of the behaviour of these connections at elevated temperatures and in the post-fire, is of great importance. In the current study, eight small scale experimental fire tests on welded connections between I-shape beams and cylindrical columns have been conducted. Four tests are aimed at investigating the structural performance of this connection at elevated temperature. In other tests, post-fire behaviour of these connections has been studied to investigate their residual structural strength.
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Zhang, Jiaqing, Shouxiang Lu, Qiang Li, Richard Kwok Kit Yuen, Bing Chen, Man Yuan i Changhai Li. "Smoke filling in closed compartments with elevated fire sources". Fire Safety Journal 54 (listopad 2012): 14–23. http://dx.doi.org/10.1016/j.firesaf.2012.08.003.
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Morovat, Mohammed Ali, Jin Woo Lee, Michael D. Engelhardt, Eric M. Taleff, Todd A. Helwig i Victoria A. Segrest. "Creep Properties of ASTM A992 Steel at Elevated Temperatures". Advanced Materials Research 446-449 (styczeń 2012): 786–92. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.786.
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In moving towards an engineered performance-based approach to structural fire safety, a sound knowledge of the elevated-temperature properties of structural steel is crucial. Of all mechanical properties of structural steel at elevated temperatures, material creep is particularly important. Under fire conditions, behavior of steel members and structures can be highly time-dependent. As a result, understanding the time-dependent mechanical properties of structural steel at high temperatures becomes essential. This paper presents preliminary results of a comprehensive on-going research project aimed at characterizing the material creep behavior of ASTM A992 steel at elevated temperatures. Such creep properties are presented in the form of strain-time curves for materials from the web and the flanges of a W4×13 wide flange section and from the web of a W30×99 section. The test results are then compared against material creep models for structural steel developed by Harmathy, and by Fields and Fields to evaluate the predictions of these models. The preliminary results clearly indicate that material creep is significant within the time, temperature, and stress regimes expected in a builing fire. The results also demonstrate the need for a more reliable creep model for steel for strcutural-fire engineering analysis.
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Vaidya, Vinayak D., Valsson Vaghese i Preeti K. Morey. "Impact of elevated temperatures on properties of concrete with blast furnace slag as partial replacement of fine aggregate as green building material". IOP Conference Series: Earth and Environmental Science 1193, nr 1 (1.06.2023): 012024. http://dx.doi.org/10.1088/1755-1315/1193/1/012024.
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Abstract Concrete is widely used as construction material because it’s high durability and fire resistance. When any structures exposed to fire, its room temperature will raise continually, which cause deterioration of concrete structures. During high temperatures concrete loss it structural capacity and it may require strengthen and rehabilitations. This paper is an efforts to investigate the effect of elevated temperature on conventional concrete and concrete with granulated blast furnace slag( GBFS) as partial replacement of fine aggregate in proportions of 20%, 40 % and 60 % and 1 % steel fibers. The strength parameter was determine and compared with conventional concrete at controlled elevated temperatures like 200°C, 400°C, 600°C, 800°C, 1000°C for 0.5 hour, 1 hour and 1.5 hour constant heating and tested after 1.0 hours of natural cooling. This experimentation shown the strength of concrete with GBFS 40 performs well at all elevated temperatures as compared with conventional concrete.
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Sharples, Jason J., Graham A. Mills, Richard H. D. McRae i Rodney O. Weber. "Foehn-Like Winds and Elevated Fire Danger Conditions in Southeastern Australia". Journal of Applied Meteorology and Climatology 49, nr 6 (1.06.2010): 1067–95. http://dx.doi.org/10.1175/2010jamc2219.1.
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Abstract Bushfires in southeastern Australia are a serious environmental problem, and consistently cause loss of life and damage to property and other assets. Understanding synoptic processes that can lead to dangerous fire weather conditions throughout the region is therefore an important undertaking aimed at improving community safety, protection of assets, and fire suppression tactics and strategies. In southeastern Australia severe fire weather is often associated with dry cool changes or coastally modified cold fronts. Less well known, however, are synoptic events that can occur in connection with the topography of the region, such as cross-mountain flows and foehn-like winds, which can also lead to abrupt changes in fire weather variables that ultimately result in locally elevated fire danger. This paper focuses on foehn-like occurrences over the southeastern mainland, which are characterized by warm, dry winds on the lee side of the Australian Alps. The characteristics of a number of foehn-like occurrences are analyzed based on observational data and the predictions of a numerical weather model. The analyses confirm the existence of a foehn effect over parts of southeastern Australia and suggest that its occurrence is primarily due to the partial orographic blocking of relatively moist low-level air and the subsidence of drier upper-level air in the lee of the mountains. The regions prone to foehn occurrence, the influence of the foehn on fire weather variables, and the connection between the foehn and mountain waves are also discussed.
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Manea, Anthony, Saskia Grootemaat i Michelle R. Leishman. "Leaf flammability and fuel load increase under elevated CO2 levels in a model grassland". International Journal of Wildland Fire 24, nr 6 (2015): 819. http://dx.doi.org/10.1071/wf14201.
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Fire is a common process that shapes the structure of grasslands globally. Rising atmospheric CO2 concentration may have a profound influence on grassland fire regimes. In this study, we asked (1) does CO2 and soil P availability alter leaf flammability (ignitibility and fire sustainability); (2) are leaf tissue chemistry traits drivers of leaf flammability, and are they modified by CO2 and soil P availability?; (3) does CO2 and soil P availability alter fuel load accumulation in grasslands; and (4) does CO2 and soil P availability alter the resprouting ability of grassland species? We found that leaf flammability increased under elevated CO2 levels owing to decreased leaf moisture content and foliar N, whereas fuel load accumulation increased owing to decreased foliar N (slower decomposition rates) and increased aboveground biomass production. These plant responses to elevated CO2 levels were not modified by soil P availability. The increase in leaf flammability and fuel load accumulation under elevated CO2 levels may alter grassland fire regimes by facilitating fire ignition as well as shorter fire intervals. However, the increased root biomass of grasses under elevated CO2 levels may enhance their resprouting capacity relative to woody plants, resulting in a shift in the vegetation structure of grasslands.
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Li, Lang, Yao Chen, Chao He, Chong Wang, Hong Zhang, Qingyuan Wang, Yongjie Liu i Guomin Zhang. "Recovery Behavior of the Macro-Cracks in Elevated Temperature-Damaged Concrete after Post-Fire Curing". Materials 15, nr 16 (18.08.2022): 5673. http://dx.doi.org/10.3390/ma15165673.
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Studying the recovery of fire-damaged concrete is of huge economic and environmental significance. The recovery of thermal-induced cracks of fire-damaged concrete leads to the recovery of strength after post-fire curing. To identify the crack recovery behavior of fire-damaged concrete after post-fire curing and its relationship with the recovery of strength, in this study, concrete samples exposed to 400, 600, and 800 °C were treated with the post-fire curing process. The compressive strength recovery was investigated, as well as the crack recovery in terms of the crack length. Moreover, the recovery of the cracks was studied and divided into the categories of mortar cracks and mortar-aggregate interfacial cracks. The results indicate that, after being exposed to high temperatures, the interfacial crack was the main type of crack, and it could clearly be recovered by post-fire curing. The recovery of compressive strength mainly resulted from the recovery of interfacial cracks. The findings of this study can provide practical guidance for the application of post-fire curing to the recovery of fire-damaged concrete structures.
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Illia, Tkalenko, Tretyakov Alexey i Wald František. "Analytical Model for Steel Fibre-Reinforced Concrete-Filled Tubular Columns Exposed to Fire". European Journal of Engineering and Technology Research 8, nr 1 (17.02.2023): 66–74. http://dx.doi.org/10.24018/ejeng.2023.8.1.2966.
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This study proposes an analytical model for the evaluation of the mechanical behaviour of circular hollow section columns infilled with steel fibre-reinforced concrete when exposed to elevated temperatures in a fire situation. This work includes the discussion of the results from a sensitivity analysis conducted through numerical simulation and the development of an analytical model based on the prEN1994-1-2:2021 European standard for the design of reinforced concrete structures exposed to fire. The sensitivity analysis aims to compare the fire resistance of centrally and eccentrically loaded circular hollow section columns infilled with plain and steel fibre-reinforced concrete. The proposed analytical model for determining the design buckling load of composite steel fibre-reinforced concrete-filled tube columns in a ?re situation is ready to serve as an annexe or supplementary technical document to the EN1994-1-2:202x standard.
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Dhabale, Ms Harsha R., i Prof Deepa Telang. "The Effect of Elevated Temperatures on the Behavior of Concrete Material". International Journal for Research in Applied Science and Engineering Technology 11, nr 2 (28.02.2023): 730–33. http://dx.doi.org/10.22214/ijraset.2023.49123.
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Abstract: The purpose of this study was to provide an overview of the effect of elevated temperature on the behavior of concrete materials. The effects of elevated temperatures on the properties of common portland cement concretes and manufacturing materials are summarized. The effect of elevated temperature on conventional concrete, GGBS concrete and BFS concrete is considered and the performance is compared with the strength of conventional concrete. Concrete in case of an unexpected fire, the properties of the concrete will change after the fire. The building must be designed to withstand high temperatures and also mainly fire. When exposed to high temperatures, such as during a fire, the mechanical properties of concrete such as strength, modulus of elasticity and volume stability are significantly reduced. Concrete structure is exposed to high temperatures, it degrades in many different ways, such as color, compressive strength, elasticity, and high temperature affects concrete density and surface appearance
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Good, P., M. Moriondo, C. Giannakopoulos i M. Bindi. "The meteorological conditions associated with extreme fire risk in Italy and Greece: relevance to climate model studies". International Journal of Wildland Fire 17, nr 2 (2008): 155. http://dx.doi.org/10.1071/wf07001.
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The meteorological conditions associated with elevated and extreme long- and short-timescale forest fire risk are investigated by validating and diagnosing the Canadian Fire Weather Index (FWI) in the context of Tuscany in Italy, and Thessaloniki, Athens and Heraklion in Greece. The aim is to provide information to assist diagnosing experiments that use output from climate models to calculate FWI values. Links are made from fire risk to the widely used FWI, and then to the underlying meteorology, complementing other more complex fire risk model studies. First, the information about Mediterranean fire risk provided by the FWI is assessed by comparing the observed number of fires per day with FWI values based on the locally observed meteorology. This shows that the FWI provides some relatively consistent information for different locations, and suggests useful FWI thresholds indicating elevated and extreme fire risk. Then, the FWI system is split according to contributions from long- and short-timescale components, in a different way than usually adopted in the literature. Using the FWI thresholds suggested above, the long- and short-timescale meteorological conditions causing elevated and extreme FWI values are diagnosed. The results may help studies that investigate what aspects of projected climate change drive changes in fire weather risk, compare fire risk calculations from different climate models, or assess how climate models can be improved to provide better fire risk projections.
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Zhao, Bo Ming, Gai Fei Peng i Ting Yu Hao. "Behavior of Densified Normal Strength Concrete under Elevated Temperature". Key Engineering Materials 405-406 (styczeń 2009): 405–8. http://dx.doi.org/10.4028/www.scientific.net/kem.405-406.405.
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This paper presents an experimental investigation on fire resistance of densified normal strength concrete (DNSC), at water/binder (W/B) ratios of 0.45, 0.36, and 0.32, of which compressive strength of 28-days ranged from 42.5 MPa to 56.3 MPa. The results of the spalling test reveal that DNSC encountered explosive under high temperature. Polymer fiber can be used to improve fire resistance of DNSC. DNSC subjected to high temperature lost its mechanical properties in a similar manner to that of high-strength concrete.
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G, Lavanya, Dr Prasad CSMV i Dr Rudraswamy M. P. "Analysis of Different Grades of Reinforced Concrete Beam After Exposure to Elevated Temperature Using Abaqus". International Journal for Research in Applied Science and Engineering Technology 11, nr 4 (30.04.2023): 1862–69. http://dx.doi.org/10.22214/ijraset.2023.50380.
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Abstract: The effect of fire causes cracking, spalling of concrete, micro-cracking, chemical decomposition. These can impact in reducing its strength, stability , load bearing capacity. After the beam exposure to elevated temperature it is necessary to retrofit and re-strengthing the existing beam by any of the retrofitting method. In this analysis carbon fibre reinforced polymer (CFRP) method adopted. The load-deflection behaviour of beam exposure to temperature is analysed using Abaqus. Two different grades of reinforced concrete of M25 grade and M30 grade were analysed. The beam exposure to temperature of about 400⸰C for the time duration of 1 hour. Fire effect is applied all around the beam. After being exposure to high temperature, the existing beam was retrofitted using the CFRP technology to reinforce it.
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Ab-Kadir, Mariyana Aida, i A. S. M. Abdul Awal. "Finite Element Modelling of Reinforced Concrete Slab at Elevated Temperature Using ABAQUS". Applied Mechanics and Materials 752-753 (kwiecień 2015): 623–27. http://dx.doi.org/10.4028/www.scientific.net/amm.752-753.623.
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This paper investigates the finite element modelling of the temperature distributions of reinforced concrete slab using a general purpose non-linear finite-element program, ABAQUS. The reinforced concrete slab is tested under exposure to designed fire in order to validate the shell element in in the ABAQUS program. The modelling results showed agreement with the fire test and it demonstrated that the ABAQUS shell element can be used to predict fire behaviour within reinforced concrete slab in elevated temperature conditions.
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Kreye, Jesse K., J. Kevin Hiers, J. Morgan Varner, Ben Hornsby, Saunders Drukker i Joseph J. O’Brien. "Effects of solar heating on the moisture dynamics of forest floor litter in humid environments: composition, structure, and position matter". Canadian Journal of Forest Research 48, nr 11 (listopad 2018): 1331–42. http://dx.doi.org/10.1139/cjfr-2018-0147.
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Much of fire behavior is driven by fine-scale patterns of fuel moisture; however, moisture predictions typically occur over large scales. The source of fine-scale variation in moisture results from a combination of fuelbed properties and overstory forest structure that influences water movement and distribution of solar radiation. Fine-scale moisture variation is of particular relevance in humid forests managed with frequent prescribed fire where fire behavior variation is tightly linked to differential fire effects. Results of a three-tiered experiment combining laboratory and field methods demonstrated that solar radiation exerted a strong influence on fuel moisture patterns in a temperate humid pine forest. Infrared radiation more rapidly dried Quercus and Pinus litter in laboratory experiments compared with controls. Litter exposed to sunlight during small-scale outdoor experiments was significantly drier than shaded litter. Quercus litter was wetter than Pinus on mornings, but dried more rapidly, becoming drier than Pinus litter by mid-day when exposed to sunlight. Field observations validated small-scale outdoor and laboratory results but also revealed the influence of fuel position: elevated litter was wetter than ground-level litter at peak burning time. Results provide insight into how overstory structure and composition may influence fine-scale heterogeneity of surface moisture dynamics and fire behavior.
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Bydžovský, Jiří, Ámos Dufka i Tomáš Melichar. "Polymer-Modified Cement Composites with Increased Resistance to Elevated Temperatures". Advanced Materials Research 688 (maj 2013): 158–64. http://dx.doi.org/10.4028/www.scientific.net/amr.688.158.
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The paper informs on partial results of the research focused on improvement of resistance of cement composites towards actuation of high temperatures invoked by formation of fire. Specifically it is an optimisation of cement composites with use of alternative raw material resources. These cement composites are primarily designed for reconstructions of reinforced concrete constructions. Basic characteristics were tested with specimens exposed in laboratory conditions to an ambient characterized with increased temperatures simulating fire in real construction.
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Wang, Yuedong, Xiaorun Li, Peng Liu, Changdong Wu, Chuhan Liu, Lijing Zeng, Wentao He i Tiantian Yin. "Mechanical Behavior of High-Strength Bolted Joints Fabricated from Fire-Resistant Steel at Elevated Temperatures". Advances in Materials Science and Engineering 2022 (15.11.2022): 1–14. http://dx.doi.org/10.1155/2022/8265019.
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The use of fire-resistant steel is an effective way to alleviate fire safety issues in steel structures. Considering the limited research on bolted joints fabricated from fire-resistant steel, this study presents the results of the experimental investigation on the mechanical behavior of 40 specimens of bolted joints at room temperature and elevated temperatures (20°C∼700°C). These specimens are assembled with fire-resistant steel plates and fire-resistant high-strength bolts (or ordinary high-strength bolts). The mechanical behavior of these specimens was investigated, which included the failure mode, deformation performance, and degradation of bearing capacity. The experimental results show that the treatment of the friction surface (specifically, impeller blasting and sprayed hard quartz sand) has a negligible effect on the ultimate strength of specimens and a relatively significant effect on the slip strength. In addition, reduction factors of the tensile strength (KN) and slip strength (KS) for both fire-resistant bolt specimens and ordinary high-strength bolt specimens decrease with the increase in temperature, especially in the case of elevated temperatures ranging from 400°C to 700°C. Prediction models with different reliability degrees are proposed to calculate the degradation of tensile strength under elevated temperatures, which has the potential to be used for the fire-resistant design of steel connections and structures.
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Marsden-Smedley, Jon B., Wendy R. Anderson i Adrian F. Pyrke. "Fuel in Tasmanian Dry Eucalypt Forests: Prediction of Fuel Load and Fuel Hazard Rating from Fuel Age". Fire 5, nr 4 (19.07.2022): 103. http://dx.doi.org/10.3390/fire5040103.
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This paper presents equations for fuel load and fuel hazard rating (FHR) models based on the time since last fire for dry eucalypt forests in eastern Tasmania. The fuel load equations predict the load of the surface/near-surface and elevated fine fuel. The FHR equations predict the surface, near-surface, combined surface and near-surface, bark, and overall FHR. The utility of the “Overall fuel hazard assessment guide” from Victoria, Australia, is assessed for Tasmanian dry eucalypt forests: we conclude that, when fuel strata components are weighted according to their influence on fire behaviour, the Victorian guide provides a rapid, robust, and effective methodology for estimating FHR. The equations in this paper will be used for operational planning and on-the-ground performing of hazard reduction burning, prediction of fire behaviour for fire risk assessments and bushfire control, and providing inputs into the new Australian Fire Danger Rating System.
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Tan, Qinghua, Leroy Gardner i Linhai Han. "Performance of Steel-Reinforced Concrete-Filled Stainless Steel Tubular Columns at Elevated Temperature". International Journal of Structural Stability and Dynamics 19, nr 01 (20.12.2018): 1940002. http://dx.doi.org/10.1142/s0219455419400029.
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Steel-reinforced concrete-filled stainless steel tubular (SRCFSST) columns combine the advantages of concrete-filled stainless steel tubular (CFSST) columns and steel-reinforced concrete (SRC) columns, resulting in excellent corrosion resistance, good economy, good ductility, and excellent fire resistance. Thus, SRCFSST columns have many potential structural engineering applications, especially in offshore structures. The performance of SRCFSST columns at elevated temperatures is investigated by finite element (FE) analysis in this paper. Firstly, FE models capable of capturing the full load-deformation response of structural members at elevated temperatures are developed and validated against relevant published tests on CFSST and SRC columns under fire conditions. Based on the validated FE models, the behavioral mechanisms of the SRCFSST columns under fire are explained by analysis of the sectional temperature distribution, typical failure modes, axial deformation versus time response, and load redistribution. Finally, the fire resistance of SRCFSST columns is evaluated in comparison to CFSST columns with equivalent sectional load-bearing capacity at ambient temperature or equivalent steel ratios. The results lay the foundation for the development of fire resistance design rules for SRCFSST columns.
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Bisby, Luke, i Tim Stratford. "Design for fire of concrete elements strengthened or reinforced with fibre-reinforced polymer: state of the art and opportunities from performance-based approaches". Canadian Journal of Civil Engineering 40, nr 11 (listopad 2013): 1034–43. http://dx.doi.org/10.1139/cjce-2012-0506.
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Recent years have seen widespread success applying fibre-reinforced polymer (FRP) materials for internal reinforcement and externally bonded strengthening of concrete structures. However, considerable reductions in mechanical and bond properties of FRP materials at elevated temperatures continue to hinder their application in buildings, where structural fire-resistance ratings are typically required. To meet currently imposed fire safety requirements, FRP materials often require supplemental fire protection insulation or thick concrete cover to maintain their temperature below an assumed (though not currently well-defined) “critical” value during an assumed standard fire exposure. Such requirements are based on a definition of structural fire resistance that is rooted in a prescriptive framework and that fails to take advantage of the state of the art in performance-based structural design for fire safety. This paper is intended to present a summary of the state of the art in this area and also to demonstrate clear opportunities for internal FRP reinforcement and external FRP strengthening of concrete elements that may arise from taking a performance-based fire safety design approach.
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Haque*, Md Mustafeezul, Dr Sabih Ahmad, Abdul Hai i Md Marghoobul Haque. "Effect of Geopolymer Concrete Encased I-Section and Geopolymer CFST Column Under Fire". International Journal of Innovative Technology and Exploring Engineering 10, nr 10 (30.08.2021): 51–58. http://dx.doi.org/10.35940/ijitee.i9350.08101021.
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Geopolymer concrete can resist fire quite well when compared with conventional concrete. Recent studies to observe the behaviour of geopolymer composite column under the effect of fire are very few. In this paper results in terms of stress, strain and deformation of geopolymer composite column expressed to elevated temperature are presented. It was observed that geopolymer composite column performs better at elevated temperatures than the conventional composite column. This tests are performed with four composite column with geopolymer concrete and conventional concrete which is tested at four elevated temperatures i.e., 400 oC, 500 oC, 600 oC, 700 oC and 800 oC to evaluate the strength parameters. It results geopolymer concrete column can be used where fire disaster chances are high.
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Chandrakanth, V., i Srikanth Koniki. "Effect of Review elevated temperature on geo-polymer concrete – A Review". E3S Web of Conferences 184 (2020): 01090. http://dx.doi.org/10.1051/e3sconf/202018401090.
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The study on the effect of elevated temperature on Geo-polymer concrete (GPC) got its significance because conventional concrete start to deteriorate around 4000C. GPC gains attention as it is eco-friendly and economical, by utilizing industrial by-products. GPC also an alternate solution as the raw materials to produce cement are depleting day by day. GPC gains strength by geo-polymerization with the reactions between mineral admixtures and alkaline solutions. This paper presents the studies on general properties and advantages of GPC over conventional concrete which depend on properties of binder, type of curing etc. Current study mainly concentrates on effect of elevated temperatures and post fire properties of GPC depending upon rate of heating, duration of fire and maximum high temperature. Strength and durability recovery of fire damaged concrete is discussed.
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Trickl, T., H. Vogelmann, H. Flentje i L. Ries. "Elevated ozone in boreal fire plumes – the 2013 smoke season". Atmospheric Chemistry and Physics Discussions 15, nr 9 (6.05.2015): 13263–313. http://dx.doi.org/10.5194/acpd-15-13263-2015.
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Abstract. In July 2013 very strong boreal fire plumes were observed at the northern rim of the Alps by lidar and ceilometer measurements of aerosol, ozone and water vapour for about three weeks. In addition, some of the lower-tropospheric components of these layers were analyzed at the Global Atmosphere Watch laboratory at the Schneefernerhaus high-altitude research station (2650 m a.s.l., located a few hundred metres south-west of the Zugspitze summit). The high amount of particles confirms our hypothesis that fires in the Arctic regions of North America have a much stronger impact on the Central European atmosphere than the multitude of fires in the United States. This has been ascribed to the prevailing anticyclonic advection pattern during favourable periods and subsidence, in contrast to warm-conveyor-belt export, rainout and dilution frequently found for lower latitudes. A high number of the pronounced aerosol structures were positively correlated with elevated ozone. Chemical ozone formation in boreal fire plumes is known to be rather limited. Indeed, these air masses could be attributed to stratospheric air intrusions over remote high latitude regions obviously picking up the aerosol on their way across Canada. In one case subsidence from the stratosphere over Siberia over as many as 15 to 20 days without increase in humidity was observed although a significant amount of Canadian smoke was trapped. These coherent air streams lead to rather straight and rapid transport of the particles to Europe.
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Maraveas, C., Y. C. Wang i T. Swailes. "Elevated temperature behaviour and fire resistance of cast iron columns". Fire Safety Journal 82 (maj 2016): 37–48. http://dx.doi.org/10.1016/j.firesaf.2016.03.004.
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White, Christopher C., Kar Tean Tan, Donald L. Hunston i Eric W. Byrd. "Elevated temperature adhesion testing of spray-applied fire-resistive materials". Fire and Materials 40, nr 4 (20.03.2015): 519–34. http://dx.doi.org/10.1002/fam.2307.
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Maljaars, Johan, i Gianfranco De Matteis. "Structural Response of Aluminium T-Stub Connections at Elevated Temperatures and Fire". Key Engineering Materials 710 (wrzesień 2016): 127–36. http://dx.doi.org/10.4028/www.scientific.net/kem.710.127.
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Many aluminium structures contain welded and bolted connections that are modeled as one or more equivalent T-stubs – also referred to as tension zone components – for the structural assessment. Knowledge on the structural behavior of such T-stubs is thus essential for proper designs. However, this behavior has never been checked for fire conditions. In this paper, the structural behavior of aluminium T-stubs exposed to fire is studied through a combination of tests, finite element simulations, and theoretical models. A safe and conservative assessment procedure is developed for determining the critical temperature, based on the material deterioration as a function of temperature. This enables engineers and practitioners to determine a conservative value of the fire resistance.
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Allam, Ahmed, Ayman Nassif i Ali Nadjai. "Behaviour of restrained steel beam at elevated temperature – parametric studies". Journal of Structural Fire Engineering 10, nr 3 (9.09.2019): 324–39. http://dx.doi.org/10.1108/jsfe-11-2018-0036.
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Purpose This paper aims to investigate computationally and analytically how different levels of restraint from surrounding structure, via catenary action in beams, affect the survival of steel framed structures in fire. This study focuses on examining the mid-span deflection and the tensile axial force of a non-composite heated steel beam at large deflection that is induced by the catenary action during exposure to fires. The study also considers the effect of the axial horizontal restraints, load-ratio, beam temperature gradient and the span/depth ratio. It was found that these factors influence the heated steel beam within steel construction and its catenary action at large deflection. The study suggests that this may help the beam to hang to the surrounding cold structure and delay the run-away deflection when the tensile axial force of the beam has been overcome. Design/methodology/approach This paper is part one of the parametric study and discusses both the effect of the axial horizontal restraints and load-ratio on the heated steel-beam. Reliance on the prescriptive standard fire solutions may lead to an unpredicted behaviour of the structure members if the impact of potential real fires is not considered. Findings Variation of the horizontal end-restraint level has a major effect on the behaviour of the beam at high deflection, and the loading on a beam at large displacement can be carried effectively by catenary behaviour. An increase of axial horizontal stiffness helps the catenary action to prevent run-away at lower deflections. The studies also investigated the influence of varying the load ratio on the behaviour of the heated beam at large deflection and how it affects the efficacy of the catenary action. The study suggests that care should be taken when selecting the load ratio to be used in the design. Originality/value In a recent work, the large deflection behaviours of axially restrained corrugated web steel beam (CWSB) at elevated temperatures were investigated using a finite element method (Wang et al., 2014). Parameters that greatly affected behaviours of CWSB at elevated temperatures were the load ratio, the axial restraint stiffness ratio and the span–depth ratio. Other works included numerical studies on large deflection behaviours of restrained castellated steel beams in a fire where the impact of the catenary action is considered (Wang, 2002). The impact of the induced axial forces in the steel beam during cooling stage of a fire when the beam temperature decreases, if thermal shortening of the beam is restrained, large tensile forces may be induced in the beam (Wang, 2005; Allam et al., 2002). A performance-based approach is developed for assessing the fire resistance of restrained beams. The approach is based on equilibrium and compatibility principles, takes into consideration the influence of many factors, including fire scenario, end restraints, thermal gradient, load level and failure criteria, in evaluating fire resistance (Dwaikat and Kodur, 2011; Allam et al., 1998).
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Zhao, Dong Fu, Zuo Kai You i Dong Dong Liu. "Overview of Experimental Study and Theoretical Analysis of Concrete Beams after High Temperature". Advanced Materials Research 446-449 (styczeń 2012): 2951–54. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2951.
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After high temperature, mechanical properties and fire-resistant performance of concrete members has become one of the hotspots of study on fire resistance of structures. In this paper, the deficiencies of concrete beams at elevated temperature test and theoretical analysis are pointed out, the future prospects of concrete beams at elevated temperature is disscussed, some key problems are proposed to solve in the future.
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Zulkifly, Khairunnisa, Heah Cheng-Yong, Liew Yun-Ming, Ridho Bayuaji, Mohd Mustafa Al Bakri Abdullah, Shamsul Bin Ahmad, Tomasz Stachowiak i in. "Elevated-Temperature Performance, Combustibility and Fire Propagation Index of Fly Ash-Metakaolin Blend Geopolymers with Addition of Monoaluminium Phosphate (MAP) and Aluminum Dihydrogen Triphosphate (ATP)". Materials 14, nr 8 (15.04.2021): 1973. http://dx.doi.org/10.3390/ma14081973.
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Thermal performance, combustibility, and fire propagation of fly ash-metakaolin (FA-MK) blended geopolymer with the addition of aluminum triphosphate, ATP (Al(H2PO4)3), and monoaluminium phosphate, MAP (AlPO4) were evaluated in this paper. To prepare the geopolymer mix, fly ash and metakaolin with a ratio of 1:1 were added with ATP and MAP in a range of 0–3% by weight. The fire/heat resistance was evaluated by comparing the residual compressive strengths after the elevated temperature exposure. Besides, combustibility and fire propagation tests were conducted to examine the thermal performance and the applicability of the geopolymers as passive fire protection. Experimental results revealed that the blended geopolymers with 1 wt.% of ATP and MAP exhibited higher compressive strength and denser geopolymer matrix than control geopolymers. The effect of ATP and MAP addition was more obvious in unheated geopolymer and little improvement was observed for geopolymer subjected to elevated temperature. ATP and MAP at 3 wt.% did not help in enhancing the elevated-temperature performance of blended geopolymers. Even so, all blended geopolymers, regardless of the addition of ATP and MAP, were regarded as the noncombustible materials with negligible (0–0.1) fire propagation index.
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Seyam, Ahmed Maher, Samir Shihada i Rita Nemes. "Effects of polypropylene fibers on ultra high performance concrete at elevated temperature". Concrete Structures 21 (2020): 11–16. http://dx.doi.org/10.32970/cs.2020.1.2.
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This paper presents an experimental study to evaluate the influence of polypropylene on fire resistance of ultra-high performance concrete (UHPC). Concrete mixtures are prepared by using different percentages of polypropylene fibres 0%, 0.75% and 1.5%, by volume. Samples are heated to 250 or 500 °C, for exposures 2.5 or 5 hours, and tested after cooling for compressive strength and flexural tensile strength. The research includes the use of mineral admixture of a recognized, polypropylene fibre, quartz sand, superplasticizers and without using any type of aggregates other than the quartz sand. The effect on subjected samples to elevated temperature up to 250 ºC and 500 ºC for durations 2.5 hours and 5 hours was studied for each mix and comparing the results of compressive strength and tensile strength among the mixes. Results obtained, showed that adding 0.75% of polypropylenes fibres only to a concrete mixture, improved the fire resistance of the concrete by 27% and 72% when the samples exposed to 250 ºC and 500 ºC for 2.5 hours respectively, compared with concrete mixes without fibres. In addition, the residual strength was improved by 39% and 14% when the samples exposed to 250 ºC and 500 ºC for 5 hours, respectively.
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Jing, Ya Tao, i Bo Wu. "Simplified Method for Horizontal Displacement Calculation of Frames at Elevated Temperature". Advanced Materials Research 243-249 (maj 2011): 5269–72. http://dx.doi.org/10.4028/www.scientific.net/amr.243-249.5269.
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The paper extracts two types of investigated models from frames in fire according to their horizontal deformation characteristics, and provides a simplified method to calculate horizontal deformation of frames, which can be applied to single- and multi-layers frames. Compared with the results by finite element analysis, it shows that the simplified method is a feasible method for the horizontal displacement estimation of frames in fire, and the treatment of the column restraint rigidity for multi-layers frame is appropriate.
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Sabrin, Samain, Rouzbeh Nazari, Md Golam Rabbani Fahad, Maryam Karimi, Jess W. Everett i Robert W. Peters. "Investigating Effects of Landfill Soil Gases on Landfill Elevated Subsurface Temperature". Applied Sciences 10, nr 18 (14.09.2020): 6401. http://dx.doi.org/10.3390/app10186401.
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Subsurface temperature is a critical indicator for the identification of the risk associated with subsurface fire hazards in landfills. Most operational landfills in the United States (US) have experienced exothermic reactions in their subsurface. The subsurface landfill area is composed of various gases generated from chemical reactions inside the landfills. Federal laws in the US mandate the monitoring of gases in landfills to prevent hazardous events such as landfill fire breakouts. There are insufficient investigations conducted to identify the causes of landfill fire hazards. The objective of this research is to develop a methodological approach to this issue. In this study, the relationship was investigated between the subsurface elevated temperature (SET) and soil gases (i.e., methane, carbon dioxide, carbon monoxide, nitrogen, and oxygen) with the greatest influence in landfills. The significance level of the effect of soil gases on the SET was assessed using a decision tree approach. A naïve Bayes technique for conditional probability was implemented to investigate how different gas combinations can affect different temperature ranges with respect to the safe and unsafe states of these gases. The results indicate that methane and carbon dioxide gases are strongly associated with SETs. Among sixteen possible gas combinations, three were identified as the most probable predictors of SETs. A three-step risk assessment framework is proposed to identify the risk of landfill fire incidents. The key findings of this research could be beneficial to landfill authorities and better ensure the safety of the community health and environment.
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M. A. Bradford, K. T. Luu i A. Heidarpour. "Numerical studies of a steel beam in a frame sub-assembly at elevated temperatures". Electronic Journal of Structural Engineering, nr 2 (1.12.2007): 1–7. http://dx.doi.org/10.56748/ejse.752.
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The analysis of structural members in a compartment in a steel framed building subjected to fire attack is often difficult owing to the combined complexity of the material degradation and of the actions induced by thermal strains. Although such analyses can be carried out using advanced finite element packages such as ABAQUS and ANSYS, they do not permit an ‘overall feeling’ of the underlying structural mechanics to be fully articulated or understood. It is important that the response of structures under fire conditions, and the parameters that influence this response, are fully understood so that safe and economical performancebased fire designs can be achieved, and that codified treatments can be prescribed. This paper presents numerical studies of a steel beam subjected to fire attack in a steel framed compartment. The analysis is based on an analytical procedure that allows for a solution for the actions and deformations to be stated in closed form prior to the attainment of first yield of the steel at elevated temperature. It is found that the response of members under fire attack is governed by the slenderness ratio of the member subjected to elevated temperature the restraint afforded by the adjacent, cooler elements in the building frame and the applied thermal regimes.
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Naser, Mohannad, Rami Hawileh i Hayder Rasheed. "Performance of RC T-Beams Externally Strengthened with CFRP Laminates under Elevated Temperatures". Journal of Structural Fire Engineering 5, nr 1 (1.03.2014): 1–24. http://dx.doi.org/10.1260/2040-2317.5.1.1.
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This paper presents a numerical study that investigates the performance of reinforced concrete (RC) T-beams externally strengthened with carbon fibre reinforced polymer (CFRP) plates when subjected to fire loading. A finite element (FE) model is developed and a coupled thermal-stress analysis was performed on a RC beam externally strengthened with a CFRP plate tested by other investigators. The spread of temperature at the CFRP-concrete interface and reinforcing steel, as well as the mid-span deflection response is compared to the measured experimental data. Overall, good agreement between the measured and predicted data is observed. The validated model was then used in an extensive parametric study to further investigate the effect of several parameters on the performance of CFRP externally strengthened RC beams under elevated temperatures. The variables of the parametric study include applying different fire curves and scenarios, different applied live load combinations as well as the effect of using different insulation schemes with different types and thicknesses. Several observations and conclusions were drawn from the parametric investigation. It could be concluded that successful FE modeling of this structural member when exposed to thermal and mechanical loading would provide a valid economical and efficient alternative solution to the expensive and time consuming experimental testing.
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Wang, Peng Gang, Peng Zhang, Tie Jun Zhao, F. H. Wittmann i Ling Cui. "Surface Impregnation of Concrete Damaged by Elevated Temperature". Materials Science Forum 675-677 (luty 2011): 567–70. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.567.
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By now, it is well-known that concrete will lose strength after exposure to elevated temperature. In this case, the damaged concrete is extremely vulnerable with respect to ingress of water and aggressive compounds. Therefore the potential for the protection of concrete from excessive ingress of water after exposure to high temperature, as for instance in an accidental fire, has been investigated. So far, surface impregnation of concrete with silane has been proved to be beneficial to reduce water penetration. In this contribution, surface impregnation with silane was applied on concrete exposed to elevated temperature. The efficiency of surface impregnation with respect to absorption of water and salt solutions by concrete with different levels of damage induced by elevated temperature has been investigated in particular. Results indicate that the increased water absorption of damaged concrete can be reduced significantly by surface impregnation. A reduction of more than 90 % can be achieved. The effective chloride barrier established by surface impregnation can help to extend the service life of fire-exposed concrete structures.
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Kai, Yan, Zhang Yao, Cai Hao, Fan Lili i Xin Zhang. "Postfire Safety Investigation on Prestressed RPC Beams after Exposure to Elevated Temperatures". Advances in Materials Science and Engineering 2020 (8.05.2020): 1–14. http://dx.doi.org/10.1155/2020/7837418.
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Since the postfire safety of prestressed RPC beams after exposure to elevated temperatures needs to be studied and proved, this paper prepares eight smart prestressed RPC beams with intelligent sensors built in to monitor the internal temperature, force, and strain. The residual bearing tests after fire are carried out. The failure process of the beams under static load with different fire durations cover thickness of tendons, load ratio, bonded and unbonded tendons, and partial prestressing ratio, which are investigated. The load-deflection curves, crack distributions and developments, and strain variations are obtained, in addition to the damage mechanism and failure mode of the beams. The results show that the load-deflection curve of the prestressed RPC beam after fire has obviously three polylines, and the deflection points are where the cracks expand and the tendons yield. The failure procedure is the same as that of under-reinforced beams, while the height of the crushing zone is much lower than that of the balanced-reinforced beam at room temperature. The whole span deformation demonstrates a strong catenary effect, and the midspan deflection is approximately 1/40 of the effective span. The postfire safety of the bonded prestressed RPC beams is superior to that of unbonded prestressed RPC beams. The test results of this paper provide a basis for the safety performance evaluation and control of prestressed RPC beams after fire.
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Li, B., X. Y. Ren, Y. Q. Lin i L. L. Liu. "Fire Behavior of Continuous Assembled Monolithic Hollow-Ribbed Slabs". Advances in Civil Engineering 2020 (7.09.2020): 1–14. http://dx.doi.org/10.1155/2020/2940894.
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To further understand the fire behavior of assembled monolithic hollow-ribbed (AMH) slab floor, a fire test was performed on six small-scale continuous AMH slabs (two by three). In this paper, the special designed furnace and relevant experimental phenomena are briefly introduced. Detailed experimental results in the form of furnace temperatures, temperature distributions, vertical deflections, and failure criteria are presented. The test data indicate that almost all the AMH slabs showed upward displacements during the fire tests, which is very distinct with the isolated AMH slab under fire. As the edge girders transformed into the frame girders gradually, the edge girders would show displacement plateaus. The integrity of the AMH slab under elevated temperature should receive more critical role to serve as its failure criterion compared with the load bearing function. Except fire environment, boundary constraint conditions also have a considerable effect on the elevated temperature deformations of the structural elements. At last, several rational suggestions are provided to improve the fire resistance of the AMH slabs.
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Lin, Cherng Shing, Chia Chun Yu, Te Chi Chen, Shih Cheng Wang i Chian Yu Peng. "Safety Verification of Mechanical Properties of Reinforced Concrete Beam in the Fire by Applying CFD". Advanced Materials Research 647 (styczeń 2013): 802–8. http://dx.doi.org/10.4028/www.scientific.net/amr.647.802.
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Advanced countries have adopted performance-based protective design to evaluate safety of buildings for building’s function of fire protection. And they have employed technology of fire protection engineering and quantified data of theoretical numerical model to create an even more flexible evaluation method for building’s fire protection. Buildings suffered varied degree of attack from elevated temperature and thermal radiation, which leads to changes in physical, chemical and mechanical properties, might result in considerable damage to the buildings and their structure. Such damage threatens populace life. This paper uses FDS (Fire Dynamics Simulator) software to analyze thermal flow field of fire. The temperature boundary condition of simulation results are then entered in the CFD (Computer Fluid Dynamics) software PHOENICS to calculate internal temperature and mechanical property of the beam. This study also integrates related experimental literatures as auxiliary to calculate thermal transmission and strength. Purpose of the above is to investigate elevated temperature and reduction of mechanical property, as well as verify safety of structure.
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Lei, Jin-Song, Wei-Bin Yuan i Long-Yuan Li. "Axial Compression Buckling of Castellated Columns at Elevated Temperatures". International Journal of Structural Stability and Dynamics 17, nr 03 (30.03.2017): 1750034. http://dx.doi.org/10.1142/s0219455417500341.
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In this paper, the axial compression buckling problem of castellated columns about the major axis when exposed to a fire is investigated. An analytical formula for calculating the critical buckling load of castellated columns is derived, which considers not only the shear deformation effect of web openings but also the non-uniform cross-section temperature distribution due to non-symmetric fire exposure. The results show that for the same average temperature, the critical buckling load of a castellated column with non-uniform temperature distribution is smaller than that of a castellated column with uniform temperature distribution. The web shear effect caused due to web openings can significantly reduce the critical buckling load of the castellated column, particularly for the columns with shorter lengths or wider flanges. However, the change of the shear effect on the critical load with different temperature distributions is very small and can be generally ignored.