A key factor regarding fire safety of timber buildings is the performance of connections between the structural elements, since this determines the load-carrying capacity of the structure. Traditional timber connections do generally perform poorly in a fire compared to surrounding parts since the joints often consist of exposed metal parts and cavities which locally decreases the fire resistance. This weakness does often lead to the appliance of gypsum which removes the aesthetic appearance of timber. Through an innovative timber connection design, the hope is that the failings at elevated temperature are changed from the connection itself to surrounding parts thus increasing the fire resistance to the limits of the connected components. Two types of glue-laminated timber connections have been built and tested at RISE facilities in Borås with the purpose to determine if these could withstand fire exposure for 90 minutes under load. The connections are assembled by expanding hollow steel tubes that clinches the members together and at the same time makes the steel tube yield against the inside of the pre-drilled hole. Pre-stresses are created in the connection during this process that avoids an initial slip if the connection is loaded, which is one of the reasons that this type of connections is suitable in earthquake-prone areas. The joint design results in a significantly increased rotational stiffness, moment capacity and embedded energy of the joint in comparison with conventional timber connections. One of the connections is designed to withstand moment forces. The specimen is built as a beam to beam connection that is subjected to a four-point bending test at both ambient and elevated temperature. The connection withstood 39.5 kNm in ambient temperature and failed after 87 minutes and 6 seconds of fire exposure under load. However, failure in elevated temperature did not occur within the connection, and visual inspection after the test indicated that the steel tubes still were in excellent condition. The connection is therefore expected to have been able to withstand 90 minutes of fire exposure. The other connection is designed to withstand shear-forces and is built as a column to beam connection that is tested at both room temperature and elevated temperature. The connection endured a maximum shear-force of 181.4 kN in ambient temperature, approximately 30 kN higher than previously performed test with identical setup, and failed after 113 minutes of fire exposure under load. The failure in elevated temperature did however not occur inside the connection. The testing is limited to unprotected connections consisting of glue-laminated timber which are tested in accordance with ISO 834. / En nyckelfaktor för brandsäkerheten i träbyggnader är prestandan hos förbanden mellan konstruktionselementen eftersom dessa bestämmer konstruktionens lastbärande kapacitet. Traditionella träförband har i allmänhet dåligt brandmotstånd i förhållande till omgivande delar, detta eftersom förbanden ofta består av exponerade metalldelar och kaviteter som lokalt försvagar brandmotståndet. Dessa svagheter motverkas ofta genom att montera gips vilket negativt påverkar träets estetiska utseende. Genom en innovativ konstruktion av träförband är hoppet att den svaga punkten vid förhöjd temperatur flyttas från själva anslutningen till omgivande delar, vilket ökar konstruktionens brandmotstånd genom att brandmotståndet då begränsas av prestandan hos de anslutna komponenterna. Två typer av limträförband har byggts och testats vid RISE-anläggningen i Borås med syfte att bestämma om dessa under belastning skulle kunna stå emot brandexponering under 90 minuter. Förbanden monteras genom att expandera ihåliga stålrör som klämmer samman elementen och samtidigt deformeras mot insidan av det förborrade hålet. Förspänningar skapas i förbandet under denna process som förhindrar en primär förskjutning om förbandet är lastat, vilket är en av anledningarna till att denna typ av anslutningar är lämpliga i jordbävningsbenägna områden. Denna konstruktion resulterar i en betydligt ökad rotationsstyvhet, momentkapacitet och inbäddad energi i jämförelse med konventionella träförband. En av anslutningarna är konstruerad för att motstå momentkrafter. Provkroppen är byggd som en balk-balkanslutning som utsätts för ett fyrapunkts böjningstest vid både rumstemperatur och förhöjd temperatur. Anslutningen klarade 39.5 kNm vid rumstemperatur och fallerade efter 87 minuter och 6 sekunder av belastning i förhöjda temperaturer. Brottet i förhöjd temperatur inträffade emellertid inte i anslutningen och den visuella inspektionen som utfördes efter testet indikerade att stålrören fortfarande var i utmärkt skick. Anslutningen bedöms därför ha kunnat motstå 90 minuters brandexponering. Det andra förbandet är konstruerat för att motstå tvärkrafter och är byggt som en pelare-balkanslutning som testas vid både rumstemperatur och förhöjd temperatur. Anslutningen klarade en maximal skjuvkraft på 181.4 kN vid rumstemperatur, cirka 30 kN högre än tidigare utfört test med identisk uppställning, och fallerade efter 113 minuters belastning i förhöjd temperatur. Brottet i förhöjd temperatur inträffade emellertid inte i själva anslutningen. Testerna är begränsade till oskyddade förband bestående av limträ som under brandpåverkan testas enligt ISO 834.

Le scellement chimique est une technique d’assemblage structural permettant de connecter et d’assurer le transfert d’efforts entre deux éléments adjacents en béton, à travers le collage d’une armature en acier à l’aide d’une résine polymère. Les scellements chimiques ont été initialement utilisés dans les ouvrages en béton armé pour la rénovation, l’extension et la réparation des structures à travers l’ajout de nouvelles sections de béton aux éléments existants. L’évolution, au fil du temps, des propriétés mécaniques et des propriétés d’adhérence des résines polymères a permis d’améliorer le comportement mécanique des scellements chimiques, leur permettant d’atteindre des propriétés équivalentes ou même supérieures à celles des ancrages mécaniques classiques, à des températures normales de service. Ainsi, les scellements chimiques ont pu progressivement substituer les ancrages mécaniques classiques dans certaines applications, en proposant des solutions plus avantageuses et en offrant plus de flexibilité pour répondre aux exigences architecturales. Cependant, le comportement mécanique des scellements chimiques est principalement gouverné par celui des résines polymères, qui demeurent très sensibles à la variation de la température. Par conséquent, l’augmentation de la température au niveau des scellements chimiques présente un risque potentiel affectant leur sécurité d’utilisation. Par ailleurs, une situation d’incendie présente un danger sérieux qui doit être considéré lors du dimensionnement des scellements chimiques. Récemment, la technique des scellements chimiques, exclusivement utilisée dans les ouvrages en béton armé, a été transférée à la construction des ouvrages bois, sous l’appellation de « goujons collés ». Cette technique, originellement utilisée dans la rénovation et le renforcement des monuments historiques, est aujourd’hui employée dans la construction neuve grâce à la bonne tenue mécanique et séismique et aussi à la possibilité qu’elle offre pour réaliser des assemblages invisibles. Cependant, les goujons collés sont aujourd’hui confrontés aux mêmes problématiques que les scellements chimiques, notamment vis-à-vis l’augmentation de la température. L’objectif de cette thèse est d’étudier l’évolution du comportement mécanique de ces deux systèmes d’assemblages dans le but de proposer une méthode de dimensionnement permettant d’assurer leur tenue structurale en situation d’incendie. L’étude est répartie sur quatre niveaux :i. Etude du comportement des ancrages chimiques à l’échelle des matériaux à travers des essais de caractérisation des constituants de l’ancrage, avec une focalisation particulière sur l’étude des phénomènes se produisant à haute température dans la résine polymère.ii. Etude du comportement global de l’ancrage par le biais d’essais d’arrachement à haute température, à effort constant et à température stabilisée, réalisés sur des scellements chimiques dans des cylindres en béton et des goujons collés dans des parallélépipèdes en lamellé-collé d’épicéa.iii. Etude du comportement mécanique à haute température des ancrages chimiques à l’échelle de la structure à travers la réalisation d’un essai au feu à l’échelle 1 sur une dalle en console ancrée chimiquement dans un mur en béton par 8 scellements chimiques. Les résultats de cet essai ont permis de valider la méthode de dimensionnement proposée pour prédire la durée de résistance au feu des scellements chimiques lors d’une situation d’incendie.iv. Etude théorique portant sur l’évolution de la distribution des contraintes le long de l’ancrage lors d’une variation de la température, à travers le développement d’un modèle non linéaire de cisaillement différé « Shear-lag », permettant d’obtenir les profils théoriques des contraintes pour une distribution thermique quelconque, à partir des données d’entrée expérimentales obtenues par des essais d’arrachement / Post-installation of rebars is a structural joining technique allowing the connection and the load transfer between two neighboring structural elements using steel rebars and adhesive polymers. Post-installed rebars were initially used in concrete constructions in retrofitting, extension and in repairing structures by adding new concrete sections to existing elements. Over the time, the improvement in mechanical and adhesion properties of polymer adhesives have allowed to enhance the mechanical behavior of post-installed rebars and led to achieve equivalent or even higher mechanical responses than cast-in place rebars at normal operating temperatures. Thus, post-installed rebars have gradually replaced cast-in place rebars in new constructions for some applications by offering advantageous solutions and flexibility allowing meeting the high architectural requirements. However, the mechanical behavior of post-installed rebars is essentially governed by the mechanical properties of polymer resins, which remain highly sensitive to temperature variation. Consequently, the temperature increase of the post-installed rebars presents a potential risk affecting their safety use. Therefore, fire presents a serious hazard that should be considered when designing post-installed rebars. Recently, the technique of post-installed rebars, exclusively used in reinforced concrete structures, has been transferred to wood structures construction, and called "glued-in rods". This technique, initially used in the retrofitting and the reinforcement of historical monuments, is today used in new construction thanks to its good mechanical and seismic behavior in addition to the possibility it offers to make invisible connections. However, glued-in rods face the same problems as post-installed rebars, especially concerning the temperature increase. The aim of this thesis is to study the evolution of the mechanical behavior of these two connection techniques in order to suggest a design method allowing ensuring their safe use in a fire situation. The study is divided into four levels:i- Study of the behavior of chemical anchors at the scale of materials through characterization tests performed on the anchor components, with a particular emphasis on the study of phenomena occurring at high temperature in the polymer resin.ii- Study of the global behavior of chemical anchors by means of pull-out tests performed at high temperature, at constant load and at stabilized temperature, carried out on post-installed rebars in concrete cylinders and on glued-in rods in parallelepipeds of spruce glulam.iii- Study of the mechanical behavior at high temperature of chemical anchors at the scale of the structure through a full-scale fire test carried out on a cantilever concrete slab connected to a concrete wall using eight post-installed rebars. Test results were also used to validate the suggested design method to predict the fire resistance duration of post-installed rebars in a fire situation.iv- Theoretical study on the evolution of the stress distribution along the anchor during a temperature variation, through the development of a non-linear shear-lag model, allowing to obtain the theoretical stress profiles for any thermal distribution, from the experimental input data obtained by pull-out tests

Os métodos para se projetar um edifício com segurança adequada para a situação de incêndio são pouco estudados e aplicados no Brasil. Essa falta de estudo é ainda mais visível quando nos deparamos com o assunto compartimentação, tópico pouco desenvolvido e ainda não normatizado pela ABNT. A compartimentação, especialmente a vertical, é fundamental para a segurança à vida, pois minimiza a propagação do incêndio entre pavimentos de edifícios. Para validar os procedimentos normatizados de dimensionamento de estruturas em situação de incêndio é necessário considerar que as edificações são compartimentadas. Atualmente as exigências sobre compartimentação são apresentadas apenas em Instruções Técnicas do Corpo de Bombeiros, variando de estado para estado. Neste trabalho é apresentado um estudo sobre a compartimentação, uma análise de sua influência na segurança contra incêndio das edificações e a comparação da visão do assunto em países de quatro continentes distintos. Após um estudo comparativo entre a visão e normatização do Brasil, Portugal, Inglaterra, Hong Kong e Estados Unidos foram realizadas simulações computacionais com base na teoria dos volumes finitos e da fluidodinâmica computacional de forma a se tentar verificar de forma mais aprofundada a influência das exigências de compartimentação na real propagação de um incêndio. Por fim, o principal foco deste trabalho é demonstrar que é possível utilizar a Dinâmica dos Fluidos Computacionais (CFD) de maneira a auxiliar o estudo do incêndio, e possibilitar uma análise mais aprofundada do assunto. / Methods for designing a building with adequate fire safety are poorly studied and applied in Brazil. This lack of study is even more present in the compartmentation subject, much-undeveloped topic and not yet standardized by ABNT. The compartmentation, especially the vertical, is critical to life safety, since it minimizes the spread of fire between building floors, and to validate the standardized procedures for structures in fire situation, because an important hypothesis of design methods is the vertical compartmentation. Currently the requirements of compartmentation are only present in the Technical Instructions of the States Fire Department, varying from state to state. This paper presents a study on compartmentation, its influence on the fire safety of buildings and a comparison of the vision of some countries of four different continents on this subject. After a comparative study of the vision and standardization between countries such as Brazil, Portugal, England, Hong Kong and the United States, computer simulation based on the theory of the finite volumes and computational fluid dynamics were carried out in order to try to check thoroughly the influence of compartmentation requirements in a real fire spread. Ultimately, the main focus of this work is to demonstrate that the Computational Fluid Dynamics (CFD) can be used in order to assist the study of fire, in order to allow a more in-depth analysis of the subject.

Os métodos para se projetar um edifício com segurança adequada para a situação de incêndio são pouco estudados e aplicados no Brasil. Essa falta de estudo é ainda mais visível quando nos deparamos com o assunto compartimentação, tópico pouco desenvolvido e ainda não normatizado pela ABNT. A compartimentação, especialmente a vertical, é fundamental para a segurança à vida, pois minimiza a propagação do incêndio entre pavimentos de edifícios. Para validar os procedimentos normatizados de dimensionamento de estruturas em situação de incêndio é necessário considerar que as edificações são compartimentadas. Atualmente as exigências sobre compartimentação são apresentadas apenas em Instruções Técnicas do Corpo de Bombeiros, variando de estado para estado. Neste trabalho é apresentado um estudo sobre a compartimentação, uma análise de sua influência na segurança contra incêndio das edificações e a comparação da visão do assunto em países de quatro continentes distintos. Após um estudo comparativo entre a visão e normatização do Brasil, Portugal, Inglaterra, Hong Kong e Estados Unidos foram realizadas simulações computacionais com base na teoria dos volumes finitos e da fluidodinâmica computacional de forma a se tentar verificar de forma mais aprofundada a influência das exigências de compartimentação na real propagação de um incêndio. Por fim, o principal foco deste trabalho é demonstrar que é possível utilizar a Dinâmica dos Fluidos Computacionais (CFD) de maneira a auxiliar o estudo do incêndio, e possibilitar uma análise mais aprofundada do assunto. / Methods for designing a building with adequate fire safety are poorly studied and applied in Brazil. This lack of study is even more present in the compartmentation subject, much-undeveloped topic and not yet standardized by ABNT. The compartmentation, especially the vertical, is critical to life safety, since it minimizes the spread of fire between building floors, and to validate the standardized procedures for structures in fire situation, because an important hypothesis of design methods is the vertical compartmentation. Currently the requirements of compartmentation are only present in the Technical Instructions of the States Fire Department, varying from state to state. This paper presents a study on compartmentation, its influence on the fire safety of buildings and a comparison of the vision of some countries of four different continents on this subject. After a comparative study of the vision and standardization between countries such as Brazil, Portugal, England, Hong Kong and the United States, computer simulation based on the theory of the finite volumes and computational fluid dynamics were carried out in order to try to check thoroughly the influence of compartmentation requirements in a real fire spread. Ultimately, the main focus of this work is to demonstrate that the Computational Fluid Dynamics (CFD) can be used in order to assist the study of fire, in order to allow a more in-depth analysis of the subject.

No presente trabalho se desenvolve como proposta principal, uma investigação experimental sobre o comportamento de elementos de aço formados a frio comprimidos em temperaturas elevadas considerando a influência da restrição ao alongamento térmico. Nessa investigação foram avaliadas as distribuições de temperaturas no contorno da seção transversal e ao longo do comprimento dos elementos. Outrossim, avaliou-se a influência da restrição ao alongamento térmico sobre o comportamento mecânico dos elementos, em especial sobre o desenvolvimento das forças de restrição que surgem durante a fase de aquecimento dos mesmos. Concernente ao comportamento térmico, os resultados indicam que a temperatura resistente de elementos expostos ao calor por todos os lados deve ser determinada com base nas medições realizadas em seções a meia altura do elemento devido à distribuição não uniforme de temperatura ao longo do comprimento. Com relação ao comportamento mecânico, os resultados experimentais mostraram que a resistência pós-crítica em temperaturas elevadas desses elementos é pequena e nesse sentido é mais coerente considerar como temperatura resistente a temperatura correspondente ao momento da perda de estabilidade dos elementos. Em caráter complementar e exploratório foram realizadas análises numéricas para melhorar o entendimento do comportamento em temperaturas elevadas dos elementos de aço formados a frio investigados experimentalmente no presente trabalho. Nas análises numéricas foi avaliada uma estratégia de modelagem em elementos finitos para simular a restrição ao alongamento térmico axial em elementos comprimidos submetidos a temperaturas elevadas. Os resultados apontam que os modelos numéricos foram eficientes para prescrever força de compressão resistente em temperaturas elevadas e o tempo resistente. Por outro lado não foram eficientes para prescrever as temperaturas críticas. No âmbito normativo foram realizadas as avaliações do método de cálculo simplificado proposto na ABNT NBR 14323 (2012) e da possibilidade de adequar o método simplificado de cálculo do EUROCODE 3 parte 1.3 (2006) para o dimensionamento em temperaturas elevadas desses elementos. Os resultados sugerem que o método de cálculo simplificado da ABNT NBR 14323 (2012) foi capaz de fornecer satisfatoriamente a força de compressão resistente dos elementos investigados que se enquadravam nas exigências do método. Outrossim, sugerem que o uso do método simplificado do EUROCODE 3 parte 1.3 (2006) com redução da resistência ao escoamento e módulo de elasticidade do aço para o dimensionamento em temperaturas elevadas de elementos de aço formados a frio carece de mais investigações. / The main proposal of this work was an experimental investigation on the behavior of cold-formed steel compressed members at elevated temperatures considering the influence of restraining to the thermal elongation. In this investigation, it was evaluated the temperature distributions on the cross section and along the height of the members. Furthermore, it was evaluated the influence of restraining to the thermal elongation on the mechanical behavior of these members, in particular on the development of restraining forces during their heating phase. Concerning the thermal behavior, the results indicate the critical temperature of members exposed to heat from all sides should be determined based on measurements performed on sections located at mid-span of the members due to the non uniform temperature distribution along the height. With regards to mechanical behavior, the experimental results showed that the post-buckling resistance at elevated temperatures of these members is small and the critical temperature should be considered as the temperature corresponding to the buckling temperature. Additionally numerical analyzes were performed to better understand the behavior of the cold-formed steel members at elevated temperatures that were experimentally investigated in this study. In the numerical analyzes a modeling strategy was evaluated on finite elements to simulate the axial restraining to the thermal elongation in compressed members subjected to high temperatures. The results show that the numerical models were effective to prescribe the ultimate loads at elevated temperatures and the critical time considering the influence of the axial restraining to the thermal elongation. On the other hand, the numerical models were not effective to prescribe the critical temperature. Within the normative scope, the design method proposed in the ABNT NBR 14323 (2012) (project revision) was evaluated as well the possibility of adapting the EUROCODE 3 part 1.3 (2006) design guidelines to the design of cold-formed steel members at elevated temperatures. The results suggest that the design method proposed in the ABNT NBR 14323 (2012) (project revision) was able to accurately predict the ultimate test loads of the members that were within the requirements of the method. On the other hand, it was found that the use of the EUROCODE 3 part 1.3 (2006) design guidelines with reduction of the mechanical properties at elevated temperatures (yield strength and elastic modulus of steel) for design of compressed cold formed steel members at elevated temperature needs further investigations.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2019-03-22T17:02:16Z No. of bitstreams: 1 Guilherme Manfredini Bueno_.pdf: 3882428 bytes, checksum: 21f15ed53f487897437091a0f77fdfc5 (MD5) / Made available in DSpace on 2019-03-22T17:02:16Z (GMT). No. of bitstreams: 1 Guilherme Manfredini Bueno_.pdf: 3882428 bytes, checksum: 21f15ed53f487897437091a0f77fdfc5 (MD5) Previous issue date: 2019-01-17 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / itt Performance - Instituto Tecnológico em Desempenho da Construção Civil / Situações de incêndio possuem um grande potencial destrutivo para a sociedade. Um esforço significativo tem sido feito no Brasil para a avaliação da resistência ao fogo de alguns elementos. Entretanto, em relação às paredes de vedação ou com função estrutural, compostas por alvenarias de tijolos ou blocos, gesso ou concreto, há poucos estudos acadêmicos no país em escala real e ainda não foram feitas pesquisas com elementos de instalações prediais no interior de sistemas de compartimentação. Isto evidencia a importância desta pesquisa que buscou avaliar a resistência ao fogo de paredes através da ABNT NBR 10636: 1989, verificando a influência de aberturas destinadas a instalações elétricas e hidráulicas. Para atingir o objetivo proposto, foram confeccionadas amostras em escala real e ensaiadas no forno vertical do Instituto Tecnológico em Desempenho e Construção Civil (itt Performance), levando em consideração a curva de aquecimento padrão ISO 834/99 para verificação dos critérios de estabilidade, estanqueidade e isolamento térmico. A amostra referência (P-1) fora executada com blocos cerâmicos e revestimento argamassado, não possuindo instalação predial e, para fins de comparação, a amostra 2 (P-2) possuía aberturas com dimensões de 120 mm x 80 mm, contendo caixas de PVC para tomadas e componentes elétricos e a amostra 3 (P-3) aberturas de diâmetro 30 mm no ponto de saída de água das instalações hidráulicas. Durante a etapa de caracterização dos materiais, foram encontradas variações nas propriedades da argamassas utilizadas no revestimento das amostras. Conforme os resultados experimentais, todas as paredes mantiveram sua estabilidade e estanqueidade durante os 240 minutos de ensaio, entretanto, a capacidade de isolar termicamente foi comprometida em determinado instante. A P-1, P-2 e P-3 foram qualificadas como TRF 134 minutos, TRF 124 minutos e P-3 com TRF 193 minutos, respectivamente. O desempenho da amostra referência (P-1) foi comprometido devido ao desplacamento do revestimento argamassado e o lascamento dos blocos cerâmicos no decorrer do ensaio, o que também ocorreu na P-2. Logo, não se pode isolar os efeitos combinados da dilatação térmica diferencial, do desplacamento do revestimento, lascamento do substrato cerâmico, das propriedades dos materiais empregados, assim como da transferência de calor pelas aberturas nas amostras com instalações, que influenciaram no desempenho das paredes. Concluiu-se que, nas regiões com aberturas de instalações prediais que permitem a passagem de gases quentes, a superfície não exposta às altas temperaturas perde sua capacidade de isolamento em um menor tempo em comparação à superfície no entorno, o que reduz a resistência ao fogo de sistemas de compartimentação / Fire situations have great destructive potential for society. A significant effort has been made in Brazil to evaluate the fire resistance of some elements. However, regarding walls, composed of masonry bricks or blocks, plaster or concrete, there are few national academic studies in full scale and no research has been done with elements of buildings built inside partitioning systems. This implies the urge of this research that sought to evaluate the performance of compartmentation walls with a fire resistance rate function, verifying the influence of openings for electrical and hydraulic installations. In order to reach the proposed objective, full scale samples were constructed and tested according to the ABNT NBR 10636:1989 in the vertical furnace of the Technological Institute in Civil Construction Performance (itt Performance - UNISINOS), taking into consideration the ISO 834/14 standard heating curve to verify stability, sealing and thermal insulation criteria. The reference sample (P-1) was performed with clay blocks and coating mortar, without any type of building installation, and for comparison purposes, sample 2 (P-2) contained openings with dimensions of 120 mm x 80 mm, containing electrical installations and sample 3 (P-3) openings of 30 mm diameter for hydraulic installations. During the materials characterization stage, there were variations in the properties of the mortars used in the coating of the samples. According to the experimental results, all systems maintained their stability and sealing during the 240 minutes of test, however, the ability to thermally insultating was compromised at a certain moment. P- 1, P-2 and P-3 were qualified as TRF 134 minutes, TRF 124 minutes and P-3 with TRF 193 minutes, respectively. The performance of the reference sample (P-1) was compromised due to the mortar coating displacement and spalling of the blocks. Therefore, it is not possible to isolate the combined effects of the thermal expansion, coating displacement, spalling of the ceramic blocks, the properties of the materials employed, as well as the heat transfer from the openings in the samples with installations, which influenced in the performance of the walls. It was concluded that in regions with openings of building installations that allow the passage of hot gases, the surface not exposed to high temperatures loses its insulation capacity in a shorter time compared to the surrounding surface, which reduces the fire resistance of the compartmentation systems.

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-05-11T15:43:54Z No. of bitstreams: 1 FABRICIO LONGHI BOLINA_.pdf: 12122006 bytes, checksum: 94b786347b29331df85e06c63ee3a387 (MD5) / Made available in DSpace on 2016-05-11T15:43:54Z (GMT). No. of bitstreams: 1 FABRICIO LONGHI BOLINA_.pdf: 12122006 bytes, checksum: 94b786347b29331df85e06c63ee3a387 (MD5) Previous issue date: 2016-02-24 / Nenhuma / As recentes tragédias ocorridas no Brasil motivaram a revisão de leis e diretrizes sobre segurança contra incêndio das edificações. Paralelamente, novos requisitos de segurança foram exigidos pela norma de desempenho (ABNT, 2013a), fortalecendo o debate. Estes fatores, reforçados pela intensificação da fiscalização e das exigências para o licenciamento edilício, acentuou o dever de prever a segurança contra incêndio em projeto. Nas estruturas de concreto, as normas que definem as especificações de durabilidade, a NBR 6118 (ABNT, 2014) e NBR 12655 (ABNT, 2015), não consentem os parâmetros de segurança contra incêndio da NBR 15200 (ABNT, 2012), e vice-versa. Este trabalho visa avaliar, experimentalmente, o tempo de resistência ao fogo (TRF) de protótipos de pilares pré-fabricados produzidos com parâmetros normativos de durabilidade do concreto, comparando-os com as recomendações da NBR 15200 (ABNT, 2012). O estudo foi feito em 16 pilares, 4 para cada classe de agressividade ambiental, com seção transversal 25x25cm e altura 300cm, com diferentes classes de resistência e produzidos numa indústria de pré-fabricados, ensaiados na idade de 28 dias por 240 minutos, sem carregamento, com a curva de aquecimento da ISO 834 (ISO, 2014). Para cada pilar de mesma classe, uma espessura de cobrimento distinta foi adotada. Concluiu-se que os parâmetros de durabilidade do concreto influenciaram no grau de desplacamento, havendo, contudo, preponderância do diâmetro das barras e da espessura de cobrimento no TRF destes pilares. Os maiores diâmetros, apesar de desenvolverem temperaturas médias menores durante o ensaio, intensificaram o desplacamento de aresta, que aumentou em paralelo com a resistência à compressão nos concretos de até 63MPa, diminuindo nas resistências superiores a esta. O método analítico de verificação da NBR 15200 (ABNT, 2012) se mostrou seguro, notando-se um grau de conservadorismo intrínseco. Após o ensaio, as armaduras principais e o concreto apresentaram perda residual de resistência. / Recent tragedies in Brazil have set off a revision of laws and technical practices on fire safety in buildings. At the same time, new security requirements have become required by the brazilian performance standard (ABNT, 2013). This set of factors, enhanced by strong supervision and project approval requirements, intensified the commitment to provide fire safety in the initial design of buildings, along with other design requirements. In concrete structures, the standards that stablish the durability specifications - the NBR 6118 (ABNT, 2014) and NBR 12655 (ABNT, 2015), do not cogitate the parameters of fire safety design of the NBR 15200 (ABNT, 2012), and vice versa. This study aims to evaluate the fire resistance time of elements produced with standard durability parameters, comparing them with the NBR 15200 (ABNT, 2012) criteria. The experiment was done on 16 columns, 4 for each standard environmental aggressiveness class, with cross section of 25x25 cm and a height of 300 cm, with different resistance classes and produced in a industry, tested at the age of 28 days for 240 minutes without load, with temperature evolution attending to the ISO 834 (ISO 2014) curve. Moreover, a different thickness of concrete cover was used for each column with the same environmental aggression class. The results showed that the durability parameters influence the degree of spalling, whereas the nominal diameter and the thickness of concrete cover have greater importance in fire resistance time. While the biggest diameters of the bars produced lower temperatures, they intensified the degree of spalling that simultaneously increased with the compressive strength of the concrete up to 63MPa. The analytical verification method of NBR 15200 (ABNT, 2012) proved to be safe, with a degree of intrinsic conservatism. The reinforcement and the concrete had residual loss of strength.

Un des enjeux majeurs de la filière de construction en briques alvéolées est l’amélioration de la tenue au feu de hauts et ambitieux bâtiments, réalisés avec ces briques. L’objet de nos travaux est de développer des modèles thermo-mécaniques et des outils numériques suffisamment prédictifs pour orienter la recherche, par la simulation numérique, de produits améliorés vis-à-vis de la tenue au feu, permettant de diminuer le nombre de coûteux essais expérimentaux. Les contributions principales sont d’ordre méthodologique. Nous avons ainsi établi un dialogue entre les observations, les mesures et les résultats expérimentaux, d’un côté, les modèles et les simulations de l’autre, avec un souci permanent de diminution des coûts des simulations. Ainsi, tirant profit de résultats de mesures réalisées, nous avons développé progressivement des modélisations adaptées, en examinant l’importance des phénomènes thermiques (conduction, convection et rayonnement), en recherchant les « juste-bonnes» (par rapport aux objectifs) relations d’échanges aux multiples interfaces du problème et en introduisant le changement de phase de l’eau liée. Nous avons également été amenés à identifier, par approche inverse, certains paramètres, après avoir identifié les bons mécanismes thermo-mécaniques. Enfin, pour mieux inscrire nos travaux dans une démarche d’aide efficace à la conception, nous avons travaillé dans le cadre multimodèle et multiéchelle Arlequin pour formuler, approcher et résoudre les problèmes thermo-mécaniques résultants, comportant des zones de concentrations du gradient thermique et de singularités mécaniques. L’approche globale, élaborée et testée, en utilisant différents codes et en développant des parties d’autres, montre une capacité réelle à améliorer les calculs des structures en briques alvéolées, soumises à des chargements thermo-mécaniques. / One of the major challenges of the hollow clay brick industry nowadays is to improve the fire resistance of ambitiously tall buildings, constructed with this type of bricks. The objective of our work is to develop thermo-mechanical models and related predictive numerical tools to guide the research of improved fire-performance products and therefore reduce the number of expensive experimental tests. Our main contributions are methodological. With a permanent concern of reducing the simulation costs, we establish a dialogue between observations, measurements and experimental results, on the one hand, models and simulations on the other hand. In this regard, measurements, obtained during the experimental tests we carried out, are used to progressively develop relevant models, by examining the importance of thermal phenomena (conduction, convection and radiation), by looking for the just right transfer relations (with respect to our objectives) at the multiple interfaces of the problem and by considering the phase change of bound water. After identifying the good thermo-mechanical mechanisms, we calibrate some numerical parameters by solving an inverse problem. Moreover, to efficiently help the design of new products, we employ the multi-model and multi-scale Arlequin framework to formulate, approximate and solve resulting thermo-mechanical problems. The latters include areas of thermal gradient concentrations and mechanical singularities. Our global approach implemented and tested by developing codes and enriching others, shows a real ability of our methodology to efficiently compute structures made of hollow bricks, when subjected to thermomechanical load.

Apesar da quantidade de variáveis envolvidas, ainda persiste uma dúvida na comunidade acadêmica sobre o comportamento do concreto de alta resistência em situação de incêndio, considerando-o como mais ou menos suscetível à ocorrência do fenômeno de desplacamento (spalling) tipo explosivo. Em parte, essa dúvida decorre do fato de que, muitas vezes, os programas experimentais são conduzidos em amostras envolvendo corpos-de-prova padronizados, cilíndricos ou cúbicos, que não levam em consideração a influência de parâmetros relacionados com as dimensões dos elementos estruturais nem com a taxa e configuração das armaduras. Outros aspectos relevantes, como o tipo de agregado utilizado na mistura de concreto, bem como a idade e umidade interna do elemento ensaiado, dificilmente são abordados nas pesquisas e, muitas vezes, simplesmente são omitidos, o que dificulta a visão ampla e real do comportamento térmico do concreto de alta resistência. Esta pesquisa apresenta um programa experimental pioneiro realizado no Brasil em um pilar de concreto de alta resistência, armado, colorido, com idade de oito anos, fc,8anos de 140MPa, agregado graúdo basáltico, agregado miúdo quartzoso, seção transversal de 70cm x 70cm, 200cm de altura, ensaiado sem carregamento e com exposição de três faces pelo período de 180 minutos (3h), sob as temperaturas da curva-padrão de incêndio ISO 834. O pilar protótipo ensaiado é réplica dos pilares reais do edifício e-Tower, construído em 2002, na cidade de São Paulo, Brasil. Os resultados obtidos demonstraram que, neste caso, o concreto colorido de alta resistência comportou-se de forma íntegra frente ao fogo e que a utilização de pigmento à base de óxido de ferro, pode atuar também como um excelente termômetro natural, auxiliando na avaliação da condição da estrutura pósincêndio. / In spite of the several factors that influence the behavior of concrete columns under fire conditions, there is a belief among the research community, that the high-strength concrete is more susceptible to explosive spalling than normal-strength concrete. This doubt, in part, is attributed to the small unreinforced concrete samples (specimens) used in experimental programs, to evaluate the fire resistance of structural concrete. On the other hand, relevant aspects as the coarse aggregate type used in the concrete mixture, as well as the age and content moisture (relative humidity) are not considered in the researches and sometimes simply omitted. This research presents a pioneer experimental program, carried out in Brazil on a high strength colored reinforced concrete column (HSCC) with 200cm high, eight yearsold, fc,8years of 140MPa, basalt coarse aggregate, cross section of 700mm x 700mm, tested under no load and with three faces exposed to a standard fire curve ISO 834 for a period of 180min (3h). The column prototype is a replica of the actual columns of the e-Tower Building, constructed in 2002 in São Paulo city, Brazil. The results demonstrated concrete column integrity under experimental fire and that the iron oxide pigments can work as an excellent natural thermometer, contributing in the evaluation of the structure post-fire.

This diploma thesis is focused on behavior of cement concrete at high temperatures. The theoretical part describes processes, which take place in concrete at thermal loading and effect of this thermal load to mechanical and physical properties of concrete. Also there was described recommendation for testing physical and mechanical of concrete at high temperatures according to RILEM TC. In experimental part mixes were made with greywacke aggregate, amphibolite aggregate and with the addition of polypropylene fibers or cellulose fibers. In these mixes was determined the effect of high temperatures on the density of concrete, compressive strength of concrete and thermal strain of concrete. Further there was tested addition of 2 kg/m3 polypropylene fibers to concrete with basalt aggregate and siliceous aggregate and influence of these fibers to density of concrete, compressive strength of concrete and dynamic modulus of elasticity.