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- Load bearing capacity of stainless steel beams at elevated temperaturesPublication . Alves, Matheus Henrique; Mesquita, L.M.M.; Piloto, P.A.G.; Lopes, Nuno; Arrais, Flávio; Vila Real, Paulo M.M.; Pinho-da-Cruz, JoaquimTo analyse the load bearing capacity of stainless steel (SS) members at elevated temperatures, a set of three-point bending tests was conducted on RHS 150x100x5 beams with SS grade 1.4301. The numerical modelling of these tests has been performed at elevated temperatures, achieving close approximation to observed experimental results. The load bearing capacity difference between the numerical results and the experimental results is smaller than 10%. Analytical methods were also used to predict the load-deflection behaviour.
- Bending resistance of stainless steel beams at elevated temperaturesPublication . Alves, Matheus Henrique; Mesquita, L.M.R.; Piloto, P.A.G.; Lopes, Nuno; Arrais, Flávio; Vila Real, Paulo M.M.Structural stainless steel elements at elevated temperatures behave differently than structural carbon steels. To analyse this behaviour, a set of three-point bending tests on 150x100 RHS, Class 1 cross-section, stainless steel grade 1.4301 beams at elevated temperatures were conducted. Numerical modelling of these tests has been afterwards performed at the measured temperatures, achieving close approximation to observed experimental results.
- Fire behaviour of wood and wood-based composite panels towards the development of fire-resistant multilayer systemsPublication . Alves, Matheus Henrique; Mesquita, L.M.R.; Piloto, P.A.G.; Ferreira, Débora; Barreira, Luísa; Mofreita, FilipeThe use of sustainable natural resources has been practiced by the construction sector as a means to reduce energy demand and increase the efficiency of buildings. In this sense, wood and wood-based materials are alternative and renewable material sources that can be effectively used in building elements, such as doors and partition walls, which are required to provide adequate thermal, acoustic, and fire resistance performance. Such elements play an important role in the fire compartmentation of buildings. Appropriate selection of materials with a reduced potential of ignition and enhanced fire behaviour may reduce the heat flux, and the passage of hot gases and smoke, thus minimizing fire hazards. In the case of wood products, the combustibility of wood usually limits its use in fire-resistant components. However, the fire performance of wooden assemblies can be improved by using engineered wood products and insulation materials, which can be assembled into multilayer systems. This work investigates the performance of wood and wood-based multilayer panels exposed to ISO 834 standard fire curve to improve the knowledge about their fire resistance in terms of insulation (I) and integrity (E) criteria. The study considers pinewood, OSB (oriented strand board), and moisture-resistant MDF (medium-density fibreboard) of different thicknesses.
- Using wood and wood-based materials to develop fire-resistant doorsPublication . Alves, Matheus Henrique; Mesquita, L.M.R.; Piloto, P.A.G.; Barreira, LuísaAs prescrições relativas à resistência ao fogo no setor da construção civil têm se tornado mais exigentes e, no caso de construções à base de madeira, o cumprimento dos critérios de performance é ainda um processo de difícil execução. O uso da madeira e derivados de madeira na construção civil é também uma importante estratégia na redução do consumo de energia em edifícios. O objetivo deste trabalho é avaliar experimentalmente e numericamente o comportamento quanto à reação e resistência ao fogo de painéis e sistemas multicamada de madeira e derivados de madeira para auxiliar no desenvolvimento de portas resistentes ao fogo. O comportamento quanto à reação ao fogo de materiais como MDF, OSB, madeira sólida e espumas de poliuretano é avaliado utilizando-se o calorímetro de perda de massa, que possibilita obter resultados comparativos e dados para o desenvolvimento de modelos numéricos.
- Experimental tests and numerical simulation of the fire effect on non-load-bearing double-stud light steel framing wallsPublication . Alves, Matheus Henrique; Piloto, P.A.G.; Kimura, Érica Fernanda AikoPartition double-stud light steel framing walls provide an enhanced insulation performance when exposed to fire conditions. However, the behaviour of different configurations of such assemblies at high temperatures is still not well understood. In this sense, this study aimed to assess the fire resistance in terms of insulation requirements of double-stud light steel framing walls clad with one or two Type F gypsum plasterboards on both sides and with or without ceramic fibre cavity insulation. A series of experimental tests were conducted by subjecting small-scale specimens to ISO 834 standard fire curve and the numerical validation of each numerical model was performed using the Finite Element Method with a hybrid approach. Also, a simplified approach was proposed based on the improved design model available in the literature. The results obtained in the experimental tests revealed that a wider cavity slows the heat transfer through the wall’s cross-section, delaying the temperature rise on the unexposed gypsum plasterboard. The use of ceramic fibre cavity insulation increases substantially the fire resistance of the wall, although the heating rate of the steel studs on the exposed side is faster if compared to the specimens without cavity insulation. Moreover, concerning the specimens with the cavity partially filled with ceramic fibre, if the insulation blanket is placed towards the exposed side, enhanced fire resistance is achieved. A hybrid approach was used to carry out the numerical analysis to determine the thermal response of each model throughout fire exposure using ANSYS® Multiphysics. It was verified that using different experimental curves to represent the temperature evolution inside the cavities or insulation blankets was essential to attain improved numerical results. Also, the concept of an air thermal layer located at specific regions of the wall models led to better and more consistent results. Moreover, the modified improved design method showed consistent results when compared with the experimental values. Overall, the predicted insulation fire resistance of the model specimens agreed well with the experimental data and useful information was provided to support further numerical and experimental studies.
- Fire resistance of austenitic stainless steel beams with rectangular hollow sectionsPublication . Lopes, Nuno; Arrais, Flávio; Real, Paulo Vila; Alves, Matheus Henrique; Mesquita, L.M.R.; Piloto, P.A.G.; Pinho-da-Cruz, JoaquimThis paper presents a study on the structural behaviour of stainless steel profiles under fire conditions. An experimental campaign of three-point bending tests on rectangular hollow section beams of the grade 1.4301 (also known as 304) were conducted, considering both steady-state and transient state conditions. Prior to those tests, the mechanical characterization of the stainless steel was investigated. The constitutive laws obtained by tensile tests at high temperatures are compared with those recommended in Eurocode 3, whose respective material models were recently proposed for modifications, still requiring complete validation. In addition, numerical modelling of the bending tests has been performed afterwards achieving close approximation to the observed experimental results. Finally, analytical methods to predict the load-deflection behaviour are also presented. Good agreement between the considered methodologies was attained validating their application on the prediction of the fire behaviour of stainless steel beams.
- Fire performance of non‐load‐bearing double‐stud light steel frame walls: experimental tests, numerical simulation, and simplified methodPublication . Alves, Matheus Henrique; Constantini, Giada; Ianni, A.; Kimura, Érica Fernanda Aiko; Meda, Alberto; Piloto, P.A.G.Double-stud light steel frame (LSF) walls provide an enhanced insulation performance when exposed to fire conditions. However, the behavior of different configurations of such assemblies under fire is not well understood. Thus, this study aimed to assess the fire resistance of non-load-bearing double-stud LSF walls subjected to ISO834 standard fire. The walls were lined with one or two type F gypsum plasterboards on each side, using cavity uninsulated or insulated with ceramic fiber. The experimental tests revealed that a wider cavity slows the heat transfer through the cross-section, delaying the temperature rise on the unexposed surfaces. The use of ceramic fiber insulation substantially increases the fire resistance of the wall and when the cavity is partially filled with this material, if the blanket is placed towards the exposed side, enhanced insulation fire resistance is achieved. Based on the finite element method, a numerical validation was conducted using a special hybrid approach that used experimental temperature values inside the cavities or insulation blankets. This approximation was essential to improve the numerical results. Also, the employment of an air layer, located at specific regions of the models, helped to improve the numerical results, introducing an extra thermal resistance. A new simplified approach was proposed based on the improved design model available in the literature, and the results obtained are consistent with the experimental results. The predicted insulation fire resistance of the numerical and simplified methods agreed well with the experimental results and useful information is supplied to support further numerical and experimental studies.
- Resistência mecânica de elementos em aço inoxidável a temperaturas elevadasPublication . Lopes, Nuno; Arrais, Flávio; Vila Real, Paulo M.M.; Alves, Matheus Henrique; Mesquita, L.M.R.; Piloto, P.A.G.Apresenta-se um estudo experimental sobre a caracterização mecânica do aço inoxidável 1.4301, à temperatura normal e a altas temperaturas. As leis constitutivas obtidas são comparadas com as preconizadas no Eurocódigo 3 (EC3), cujos modelos materiais foram recentemente sujeitos a propostas de alteração. Por fim analisa-se a influência das diferentes leis constitutivas na modelação numérica de vigas com secções retangulares ocas (RHS).
- Stainless steel members strength at elevated temperaturesPublication . Lopes, Nuno; Arrais, Flávio; Vila Real, Paulo M.M.; Alves, Matheus Henrique; Mesquita, L.M.M.; Piloto, P.A.G.O presente artigo apresenta um estudo experimental sobre a caracterização mecânica do aço inoxidável austenítico 1.4301, à temperatura normal e a altas temperaturas. As leis constitutivas obtidas por ensaios à tração são comparadas com as preconizadas no Eurocódigo 3 (EC3), cujos respetivos modelos materiais foram recentemente sujeitos a propostas de alteração, necessitando ainda de completa validação. Por fim analisa-se a influência da aplicação das diferentes leis constitutivas na modelação numérica de vigas com secções retangulares ocas (RHS) e na respetiva resistência ao fogo.
- Fire behaviour of mortars with portland cement and residual diatomaceous earthPublication . Magalhães, Leandro; Zolin, Renan Calvo; Alves, Matheus Henrique; Barreira, Luísa; Ferreira, Débora; Luso, Eduarda; Mesquita, L.M.R.; Óscar, LimaThe high pollution levels produced by the manufacturing of conventional Portland cement have motivated several studies in an attempt to modernize this process with alternative binders and the conscious use of natural resources. The correct treatment of residues has become a matter of great concern. The project “BacchusTech” aims to reuse diatomaceous earth from wine filtrations, introducing them into the composition of cement mortars through the reduction of cement and sand, seeking to valorise this winemaking residue and contributing to a sustainable construction. Three compositions of Portland cement-based mortars introducing residual diatomaceous earth are studied and fire behaviour tests are performed to the obtained specimens of mortars. The characterisation of these elements regarding their reaction to fire is performed using the cone calorimeter equipment.
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