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New Developments on the Bending Resistance in Composite Slabs with Steel Deck Under Fire.

紀錄類型:	書目-電子資源 : Monograph/item
正題名/作者:	New Developments on the Bending Resistance in Composite Slabs with Steel Deck Under Fire./
作者:	da Silveira, Matheus Bez.
面頁冊數:	1 online resource (239 pages)
附註:	Source: Masters Abstracts International, Volume: 84-06.
Contained By:	Masters Abstracts International84-06.
標題:	Load. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=30208736click for full text (PQDT)
ISBN:	9798358451971

New Developments on the Bending Resistance in Composite Slabs with Steel Deck Under Fire.
da Silveira, Matheus Bez.

New Developments on the Bending Resistance in Composite Slabs with Steel Deck Under Fire. - 1 online resource (239 pages)

Source: Masters Abstracts International, Volume: 84-06.

Thesis (M.E.)--Instituto Politecnico de Braganca (Portugal), 2022.

Includes bibliographical references

Composite steel/concrete slabs can be considered a union of a reinforced concrete layer located above a profiled steel sheet which may or may not be reinforced by steel bars. This configuration allows lightness in the structure, whereas the negative mesh located on the top side of the slab needs to resist only against the concrete shrinkage; the profiled steel deck with the reinforcement bars is responsible for resisting the sagging moments.The main objective of this work is to investigate the fire effect on the bending resistance of the composite slab with steel deck, comparing the behavior of Normal Weight Concrete (NWC) and Light Weight Concrete (LWC) when submitted to standard fire. The Eurocode 1994 1-2 is responsible for providing the guidelines for structural design of composite slabs under fire conditions. This standard presents a simplified calculation model to determine the slab sagging moment. However, it neglects some important effects occurring during a fire situation, such as the air-gap effect and the influence of the concrete layer h1.In order to optimize the calculation model presented by Eurocode 1994 1-2, a parametric study was performed using trapezoidal and re-entrant steel decks geometries. This study comprises two trapezoidal models (Confraplus 60 and Polydeck 59s) and two reentrant models (Multideck 50 and Bondek) with different thicknesses for h1.This analysis consists of a non-linear transient thermal analysis using the finite element method, performed on two different software: ANSYS and MATLAB. Based on the average temperature of each component, new coefficients and calculation proposal for annex D of Eurocode 1994-1.2 are presented, and the slabs reduction load-bearing capacity is determined.By analyzing the results provided by this study, it was possible to conclude that Eurocode 1994-1.2 simplified calculation method produces a lower temperature field than the parametric curves and the New Calculation Proposal, thus confirming the current analytical method produces unsafe results. A comparison of the estimated temperatures between the New Proposal and the temperatures of Eurocode 1994-1.2 showed an average variation of 6% for composite slabs with trapezoidal profiles and 10% for composite slabs with re-entrant profiles, and this effect is intensified for the initial fire resistance classes, which can reach up to 40%. The variation in temperatures also leads to variations in the reduction of the resistant capacity of the slabs; when comparing the two analytical models, the variation is around 3% to 20% for most fire resistance classes and can reach up to 50% for the initial rating times of 30 min and 45 min.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2023

Mode of access: World Wide Web

ISBN: 9798358451971Subjects--Topical Terms:

3562902
Load.
Index Terms--Genre/Form:

542853
Electronic books.

New Developments on the Bending Resistance in Composite Slabs with Steel Deck Under Fire.
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245 1 0 $a New Developments on the Bending Resistance in Composite Slabs with Steel Deck Under Fire.
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500 $a Source: Masters Abstracts International, Volume: 84-06.
500 $a Advisor: Piloto, Paulo Alexandre Goncalves; Balsa, Carlos; Dias, Gustavo Lacerda.
502 $a Thesis (M.E.)--Instituto Politecnico de Braganca (Portugal), 2022.
504 $a Includes bibliographical references
520 $a Composite steel/concrete slabs can be considered a union of a reinforced concrete layer located above a profiled steel sheet which may or may not be reinforced by steel bars. This configuration allows lightness in the structure, whereas the negative mesh located on the top side of the slab needs to resist only against the concrete shrinkage; the profiled steel deck with the reinforcement bars is responsible for resisting the sagging moments.The main objective of this work is to investigate the fire effect on the bending resistance of the composite slab with steel deck, comparing the behavior of Normal Weight Concrete (NWC) and Light Weight Concrete (LWC) when submitted to standard fire. The Eurocode 1994 1-2 is responsible for providing the guidelines for structural design of composite slabs under fire conditions. This standard presents a simplified calculation model to determine the slab sagging moment. However, it neglects some important effects occurring during a fire situation, such as the air-gap effect and the influence of the concrete layer h1.In order to optimize the calculation model presented by Eurocode 1994 1-2, a parametric study was performed using trapezoidal and re-entrant steel decks geometries. This study comprises two trapezoidal models (Confraplus 60 and Polydeck 59s) and two reentrant models (Multideck 50 and Bondek) with different thicknesses for h1.This analysis consists of a non-linear transient thermal analysis using the finite element method, performed on two different software: ANSYS and MATLAB. Based on the average temperature of each component, new coefficients and calculation proposal for annex D of Eurocode 1994-1.2 are presented, and the slabs reduction load-bearing capacity is determined.By analyzing the results provided by this study, it was possible to conclude that Eurocode 1994-1.2 simplified calculation method produces a lower temperature field than the parametric curves and the New Calculation Proposal, thus confirming the current analytical method produces unsafe results. A comparison of the estimated temperatures between the New Proposal and the temperatures of Eurocode 1994-1.2 showed an average variation of 6% for composite slabs with trapezoidal profiles and 10% for composite slabs with re-entrant profiles, and this effect is intensified for the initial fire resistance classes, which can reach up to 40%. The variation in temperatures also leads to variations in the reduction of the resistant capacity of the slabs; when comparing the two analytical models, the variation is around 3% to 20% for most fire resistance classes and can reach up to 50% for the initial rating times of 30 min and 45 min.
520 $a As lajes mistas em aco e concreto podem ser descritas pela uniao de uma camada de concreto armado localizada acima de um perfil de aco, podendo ou nao ser reforcada por vergalhoes de aco entre as nervuras. Esta configuracao garante leveza a estrutura de modo que a malha negativa localizada no lado superior da laje resiste contra a retracao do concreto, ja o "deck" de aco perfilado e os vergalhoes de reforco sao responsaveis por resistir aos momentos de positivos da laje mista.O principal objetivo deste trabalho e investigar o efeito do fogo na resistencia a flexao das lajes mistas com plataforma de aco colaborante, comparando o comportamento do Concreto Convencional (NWC) e do Concreto de Peso Leve (LWC) quando submetidos a uma curva de incendio padrao ISO-834.O Eurocodigo 1994-1.2 e responsavel por fornecer as diretrizes para o projeto estrutural das lajes mistas sob condicoes de incendio. Esta norma apresenta um modelo simplificado de calculo para determinar o momento positivo maximo resistente da laje. Entretanto, ela negligencia alguns efeitos importantes que ocorrem durante a fase de aquecimento, como o efeito de desplacamento ("debonding effect") entre o concreto e a plataforma de aco, e tambem a influencia da camada de concreto h1.Para otimizar o modelo de calculo apresentado pelo Eurocodigo 1994-1.2, foi realizado um estudo parametrico utilizando diferentes geometrias de perfis de plataformas de aco, como: trapezoidais e reentrantes. Este estudo compreende dois modelos trapezoidais (Confraplus 60 e Polydeck 59s) e dois modelos reentrantes (Multideck 50 e Bondek) com diferentes espessuras de h1.Este estudo consiste na elaboracao de analises termicas transientes nao-lineares atraves do Metodo de Elementos Finitos (MEF) em dois softwares diferentes: ANSYS e MATLAB. Com base na temperatura media de cada componente, foram apresentados novos coeficientes e proposta de calculo para o Anexo D do Eurocodigo 1994-1.2. Por fim, foi possivel determinar a reducao da capacidade resistente das lajes mistas de acordo com o tempo de exposicao ao fogo, comparanado os efeitos oriundos das duas abordagens analiticas: o metodo simplificado do Eurocodigo 1994-1.2 e a Nova Proposta de Calculo.Por meio da analise dos resultados obtidos atraves deste estudo foi possivel concluir que atualmente o Eurocodigo 1994-1.2 apresenta um campo de temperaturas inferior ao das curvas parametricas e da Nova Proposta de Calculo, demonstrando assim que o metodo analitico atual produz resultados inseguros. Uma comparacao acerca da estimativa de temperaturas entre a Nova Proposta e as temperaturas do Eurocodigo 1994-1.2 possibilitou demonstrar uma variacao media 6% para lajes com perfis trapezoidais e 10% para lajes com perfis reentrantes, de modo que este efeito e agravado para as calsses iniciais de resistencia ao fogo, podendo chegar ate a 40%. A variacao nas temperaturas tambem acarreta variacoes na reducao da capacidade resistente das lajes quando comparados os dois modelos analiticos, de forma que esta variacao e na ordem de 3% a 20% para a maioria das classes de resistencia ao fogo, podendo chegar ate a 50% para os tempos iniciais de 30 min e 45 min.
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