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Authors
Advisor(s)
Abstract(s)
Este trabalho investiga o comportamento térmico de lajes mistas de aço e concreto
com perfil de chapa colaborante sob condições controladas de acidente, correspondendo
a um incêndio a atingir a superfície inferior. Esta solução mista consiste em uma cobertura
de concreto no topo de um perfil de aço. O concreto é normalmente reforçado com uma
malha de aço e também pode conter vergalhões individuais. O deck ou chapa colaborante
também atua como reforço e consequentemente pode ser exposto a condições acidentais
de incêndio.
Esta solução mista é amplamente utilizada em todos os tipos de edifícios e requer
resistência ao fogo, de acordo com os regulamentos e normas. As lajes mistas precisam
atender aos requisitos de segurança contra incêndio de acordo com os códigos de
construção. A avaliação ao fogo deste tipo de elementos é normalmente feita utilizando
testes de incêndio padrão.
Duas amostras foram preparadas para serem testadas e devem levar em
consideração os critérios de estabilidade (R), Integridade (E) e isolamento (I). O objetivo
desta investigação diz respeito à classificação de incêndio para o isolamento (I). A
classificação de incêndio para isolamento (I) é avaliada por três métodos diferentes
(simulação numérica, método simplificado e ensaios experimentais).
A simulação numérica foi realizada através da biblioteca de equações as derivadas
parciais do Matlab e também através do programa ANSYS, considerando os efeitos
térmicos da exposição a um fogo padrão. A resistência ao fogo é calculada para 196
configurações geométricas diferentes, sendo assim, 394 simulações numéricas foram
realizadas a fim de avaliar o efeito da espessura da camada de concreto e da espessura da
chapa colaborante de aço. A resistência ao fogo (I) aumenta com a espessura do concreto,
de acordo com os resultados obtidos em ambos os métodos. Os resultados numéricos
também são comparados com os ensaios experimentais e comparados com o método
simplificado proposto no anexo D do Eurocódigo 4 e pela NBR 14323, que parecem estar
inseguros.
This study investigates the thermal behaviour of composite steel and concrete slabs with profile steel deck under standard fire conditions corresponding to a fire from the bottom. This composite solution consists of a concrete topping cast on the top of a steel deck. The concrete is typically reinforced with a steel mesh and may also contain individual rebars. The deck also acts as reinforcement and may be exposed to accidental fire conditions from the bottom. This composite solution is widely used in all types of buildings and requires fire resistance in accordance to regulations and standards. Composite slabs need to meet firesafety requirements according to building codes. The fire assessment of this type of elements is normally done using standard fire tests. Two samples were tested and should take into account the criterion for stability (R), Integrity (E) and insulation (I). The fire rating for (R) and (E) is not in the scope of this investigation. The fire rating for insulation (I) is evaluated by three different methods (numerical simulation, simple calculation and experimental tests). Numerical simulation was performed using Matlab partial differential equation toolbox and by the software ANSYS, for the thermal effects of standard fire exposure. The fire rating is calculated for 196 different geometric configurations, therefore, 394 simulations were performed in order to evaluate the effect of the thickness of the concrete layer and the thickness of steel deck. The fire resistance (I) increases with the thickness of the concrete, according to the results obtained with both methods. The numerical results are also compared with the simplified method proposed in the Annex D of Eurocode 4 and the Brazilian standard NBR 14323:2013, which appears to be unsafe.
This study investigates the thermal behaviour of composite steel and concrete slabs with profile steel deck under standard fire conditions corresponding to a fire from the bottom. This composite solution consists of a concrete topping cast on the top of a steel deck. The concrete is typically reinforced with a steel mesh and may also contain individual rebars. The deck also acts as reinforcement and may be exposed to accidental fire conditions from the bottom. This composite solution is widely used in all types of buildings and requires fire resistance in accordance to regulations and standards. Composite slabs need to meet firesafety requirements according to building codes. The fire assessment of this type of elements is normally done using standard fire tests. Two samples were tested and should take into account the criterion for stability (R), Integrity (E) and insulation (I). The fire rating for (R) and (E) is not in the scope of this investigation. The fire rating for insulation (I) is evaluated by three different methods (numerical simulation, simple calculation and experimental tests). Numerical simulation was performed using Matlab partial differential equation toolbox and by the software ANSYS, for the thermal effects of standard fire exposure. The fire rating is calculated for 196 different geometric configurations, therefore, 394 simulations were performed in order to evaluate the effect of the thickness of the concrete layer and the thickness of steel deck. The fire resistance (I) increases with the thickness of the concrete, according to the results obtained with both methods. The numerical results are also compared with the simplified method proposed in the Annex D of Eurocode 4 and the Brazilian standard NBR 14323:2013, which appears to be unsafe.
Description
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Keywords
Lajes mistas Resistência ao fogo Isolamento Simulação numérica Ensaios experimentais