Percorrer por autor "Fonseca, Elza M M"
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- Advanced Calculation Model Calibrated with Experimental Test of Wooden Slabs Exposed to FirePublication . Fonseca, Elza M M; Piloto, Paulo A GThe wooden slabs are structural elements with wide application, in particular, in building rehabilitation, interior spaces and in new building structures. The mechanical, thermal and acoustic properties make this material as an ideal solution for floor and roof slabs applications. However, when exposed to an accidental fire condition it is necessary to assess their vulnerable behaviour accurately. In this work, an advanced calculation model is presented, based on the use of finite elements, calibrated with experimental results. The experimental tests were performed on wooden slabs exposed to a fire from below the element. The slabs were instrumented with thermocouples to measure the temperature at different control points along the fire duration in a fire resistance furnace, following the standard fire curve ISO 834. The advanced calculation model also allows the obtained the transient effect and incorporates the non-linear wood properties. The physical behaviour of the wooden slab is conditioned by the char layer formation, and this phenomenon is also considered in the advanced calculation model.
- Analysis of simply supported wood beams at ambient and high temperaturesPublication . Fonseca, Elza M M; Gouveia, Pedro J VThe main objective of this work is to present a methodology for safety analysis of simply supported wood beams at ambient and high temperatures with a concentrated load at mid-span. Sixteen different beam configurations will be studied. All calculations were conducted according the Eurocode 5, part 1-1 and part 1-2. During this study will be analyzed the safe load bearing capacity according standards and compared with the elastic and plastic load from beam theory. The beam theory can provide sufficient accuracy up to the point of instability. The standard methods are generally conservative and they are suitable to be used for design purposes with safety. The studied beam cross sections will be in glued laminated wood, as yellow birch, with characteristics equals to a Glulam GL28H.
- Atas das 8as Jornadas de Segurança aos Incêndios Urbanos e as 3as Jornadas de Proteção Civil (8JORNINC-3JORPROCIV)Publication . Fonseca, Elza M M; Lopes, Hernâni M. L; Campos, Armando; João, Ana Maria Raposo; Magalhães, António Gonçalves; Silva, João F.Este livro de ATAS contém os artigos apresentados às 8as Jornadas de Segurança aos Incêndios Urbanos e às 3as Jornadas de Proteção Civil (8JORNINC-3JORPROCIV), que decorreram no Porto, Portugal. Na presente edição das 8JORNINC-3JORPROCIV foram submetidos 50 trabalhos, tendo sido aceites 42. Os trabalhos foram distribuídos em 8 sessões paralelas temáticas, em adição a 2 sessões plenárias, apresentados no dia 2 de junho de 2023. O evento foi iniciado e promovido em Portugal, sob a organização do professor Doutor João Paulo Rodrigues, com as 1as Jornadas de Segurança aos Incêndios Urbanos, em 2005, na Universidade de Coimbra, bem como nos anos seguintes, as 2as Jornadas de Segurança aos Incêndios Urbanos em 2011 e as 3as Jornadas de Segurança aos Incêndios Urbanos em 2013, também na Universidade de Coimbra. As edições seguintes aconteceram em diferentes locais: as 4as Jornadas de Segurança aos Incêndios Urbanos em 2014, no Instituto Politécnico de Bragança; as 5as Jornadas de Segurança aos Incêndios Urbanos em 2016, no Laboratório Nacional de Engenharia Civil em Lisboa; as 6as Jornadas de Segurança aos Incêndios Urbanos e 1as Jornadas de Proteção Civil em 2018, na Universidade de Coimbra; e as 7as Jornadas de Segurança aos Incêndios Urbanos e 2as Jornadas de Proteção Civil, em 2021, no Instituto Politécnico de Castelo Branco. As 8JORNINC apresentam grande importância num contexto atual de vários e graves incêndios urbanos, florestais e de interface em Portugal. A pertinência do tema da segurança na prevenção e no combate a incêndios, quer pelas consequências emergentes deste tipo de acidentes, quer pela necessidade de redução das ocorrências, do número de vítimas mortais, feridos, prejuízos materiais, patrimoniais, ambientais e sociais, leva a que as Jornadas se destinem a um leque alargado de profissionais e público em geral. As 3JORPROCIV têm como objetivo promover conhecimentos nas áreas da prevenção civil, de riscos e planos de emergência. Pretendem assim, contribuir para a atualização dos conhecimentos técnicos e científicos da segurança e proteção civil, no âmbito do planeamento e prevenção perante cenários de crise e emergência. As Jornadas de Proteção Civil permitem partilhar um leque de conhecimentos multidisciplinares suscetíveis de impulsionar uma intervenção por parte de técnicos, especialistas e dos agentes da proteção civil. A visão interdisciplinar e integradora dos problemas e desafios que a proteção civil apresenta será refletida na prevenção e mitigação dos riscos inerentes a uma situação de acidente. Os trabalhos apresentados nesta edição, permitirão o avanço das 8JORNINC-3JORPROCIV, através da divulgação dos recentes desenvolvimentos e do conhecimento nos domínios da segurança ao incêndio e proteção civil. Por fim, a comissão organizadora das 8JORNINC-3JORPROCIV gostaria de agradecer: - o apoio dos patrocinadores e das instituições do Sistema Científico e Tecnológico; - a todos os autores que partilharam os seus excelentes trabalhos; - e aos elementos da Comissão Científica que auxiliaram no processo de revisão. Todos em conjunto, tornaram possível a realização destas Jornadas.
- Computational model to predict the temperature distribution produced by bone cementPublication . Oliveira, Vânia C.C.; Fonseca, Elza M MBone is the third frequent location for haematogenous dissemination of malignant tumors. Patients with multiple bone metastases are exponentially growing. Bone metastases, which are frequently diagnosed late, are associated to imminent and pathological bone fractures. Metastatic disease translates an advanced tumor stage and it has a high impact in patients’ quality of life and survival. The main objective is to study the thermal effect induced by the bone cement polymerization, in the bone metastatic tumor reduction and to understand the role of such procedure and its biomechanical stabilization. To assess the clinical effect, it is important to test this methodology before its application and obtain sustained results. In this work, a computational model was developed to predict the temperature distribution produced by cement polymerization, and verify the reduction of the metastatic tumor area due the thermal effect. Different simulations produced to evaluate the necrosis effect for two cement amount sizes introduced in a cortical and spongy bone tumor. The same computational models were reproduced introducing an endomedular nail in titanium and a femoral stem in cobalt-chrome material in pathological bone fractures.
- Determination of optimal parameters in drilling composite materials to minimize the machining temperature using the Taguchi methodPublication . Lopes, A.C.; Fernandes, M.G.A.; Ribeiro, J.E.P.C.; Fonseca, Elza M MThis work aims to determine the best combination of drilling parameters which results in the smaller temperature during the bone drilling procedure. An experimental procedure was adopted with the acquisition of two biomechanical blocks from Sawbones (composite material) with similar properties to the human bone. The goal of this experiment resulted in a drilling process to assess the generated temperature on the drill bit and simultaneously on the bone material. The Taguchi method is a powerful tool in high quality system design, and proved that can be used as optimization method to determine the best parameters combination to obtain the minimum temperatures in the drilling process.
- Easy Trends to Analyse Structural Profiles: Lumped Capacitance Vs Simplified EquationPublication . Oliveira, Pedro N.; Fonseca, Elza M M; Campilho, RaulThis work presents the calculation of the temperature in different cross-sections of structural profiles (IPE, HEM, L and UAP) using the lumped capacitance method and the simplified equation from Eurocode 3 part 1-2. The lumped capacitance method allows the temperature calculation of the solid body at any time instant during the heat transient process, as a constant and uniform value. The simplified equation from Eurocode 3 part 1-2 is a simple model for heat transfer based on the uniformly distributed temperature over the cross-section surface and directly proportional to section factor of the element. Steel profiles have as almost thermal behaviour uniform during the heat transfer process when submitted to fire conditions and the lumped capacitance method allows a great simplification to estimate the temperature field in the element and may be used when Biot number is lower than unity. Therefore, thermal analysis of solids with high thermal conductivity using this method is adequate. For the studied steel profiles, a thermal analysis was also performed using the simplified equation from the Eurocode 3 part 1-2 in order to validate the obtained results from the lumped capacitance method. The results from both methods are presented for discussion and analysis
- Fire behaviour of protected W-S-W connections with a steel plate as the central member and different dowels diameterPublication . Martins, Rúben D A R; Fonseca, Elza M MThe main objective of this work is to present wood-steel-wood (W-S-W) connections in double-shear, joined by steel dowel fasteners and a steel plate as the central member. For each studied connection, different dowel diameters and external applied tensile loads in fire situation shall be taken in account. Considering the rules presented in Eurocode 5, part 1-1 and 1-2, the calculated number of dowels will be arranged in lines and columns and carry out an imposed spacing between the connectors. This work is intended to study the W-S-W connection exposed to fire using the standard curve ISO834. In the wood plates will be used a glue laminated wood, as yellow birch, with characteristics equals to GL28H. For protected connections three types of gypsum will be used in order to obtain a better insulation. Simplified equations from Eurocode 5, part 1-1 and 1-2, will be used to verify the behaviour of the connections at high temperature. A numerical procedure based on finite element method was also implemented to produce simulations focused on thermal analysis. The comparison of several results between analytical and numerical calculations showed a favourable accordance. The numerical model permits verify the effect of the steel dowels, steel plate and gypsum in the wood charring rate evolution. Even though the connection can resist for thirty minutes, is possible to observe the char layer both on protected and unprotected connection being the last the most affected.
- Fire design of wood connections loaded in shearPublication . Fonseca, Elza M M; Leite, Pedro A. S.The main objective of this work is to compare the fire resistance between wood-steel-wood (W-S-W) and wood-wood-wood (W-W-W) connections, both joined by steel dowel fasteners, in double shear. The analytical and design procedures follow simplified equations presented in Eurocode 5, part 1-1 and 1-2. A computational methodology, based on finite element method, was also implemented to produce two dimensional thermal simulations, which permits to verify the heating effect through the dowels fasteners or steel elements through the connection in study. Different cross-sections will be identified, considered as the most relevant parts, to compare the temperature distribution in the studied connections. According to the fire exposure, a thermal and transient effect will happen and a char-layer appearing in the exposure side of the connections. The measured quantity of the charred area permits to identify the lost structural material in the studied cross-sections. The charring rate will calculate and compared with the constant value proposed by the Eurocode 5, part 1-2. There are typical values for the charring rate of wood between 0.5-1.0mm/min according to Eurocode 5, part 1-2. However, as a general conclusion and additional information to help designers and professionals, the number of fasteners increases with the applied load, lower dowels diameters have higher effect in the number of fasteners, at fire exposure the steel fasteners bring the heat to inside the connections, and different wood densities affect the thermal behaviour and the charring rate evolution. The charring rate permits to quantify the lost layer thickness and the fire resistance of the connection, dependent on the chosen material density.
- Fire safety of wood-steel connectionsPublication . Fonseca, Elza M M; Silva, Lino; Leite, Pedro A. S.The main objective of this work is to present different analytical and computational methods which permit the safe design calculation of the wood-steel connections, under fire conditions. Wood is an anisotropic, heterogeneous and porous material and its behaviour varies with temperature. The increase of temperature influences the progressive degradation of wood properties. During fire exposure, it is need to determine if the charred wood connections are safe in use. Design methods require the use of analytical methodologies and computational modelling to predict the fire exposure and the components capacity to resist to this action. In this work, the authors present studied cases, that will help professionals to analyse wood-steel connections and focus the type of information needed to decide whether the charred elements are adequate or not to use. For the same wood-steel connections, different insulation materials will be analysed to compare their behaviour and determine the fire resistance in time domain.
- Numerical model to predict the effect of wood density in wood–steel–wood connections with and without passive protection under firePublication . Fonseca, Elza M M; Silva, Lino; Leite, Pedro ASThe main objective of this work is to present a numerical model to predict the effect of wood density in unprotected wood connections with an internal steel plate (wood–steel–wood), when comparing with the same connections using passive protection with gypsum plasterboard, submitted to fire conditions. Wood–steel–wood connections are made of four wood members, two on each side, with an internal steel plate that connects the pieces using steel dowel fasteners. First, analytical methodologies according to Eurocode 5 part 1-1 were used to design the connections at room temperature. After that, to predict the fire exposure and the connection ability, a numerical model was performed which permits to compare the fire resistance in wood–steel– wood connections without and with passive protection following the Eurocode 5 part 1-2. Results of the temperature and the wood char layer depth were compared using three different wood densities. The evolution of the charring rate was calculated in different locations of the connections and compared with the analytical value proposed by the Eurocode 5 part 1-2.