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Authors
Abstract(s)
Lajes mistas de concreto com chapas de aço colaborantes consistem em estruturas de concreto moldadas em fôrmas de aço que devem permanecer unidas à estrutura, agindo de forma permanente como parte da armadura para as lajes. Esta tecnologia construtiva está presente na construção civil desde os anos 80, sendo utilizada principalmente em grandes edifícios por ser uma alternativa altamente econômica quando aplicada em larga escala.
As chapas de aço desempenham um importante papel na resistência mecânica destas estruturas e quando submetidas a situações de incêndio acabam por exigir uma maior atenção pois a alta sensibilidade das propriedades térmicas e mecânicas do aço quando exposto a altas temperaturas coloca em risco estas estruturas.
A norma europeia EN 1994-1-2 é responsável por padronizar os métodos de projeto e de cálculo para verificação da segurança destas estruturas quando submetidas a situações de incêndio, e dela provém métodos simplificados de cálculo para projetistas. Entretanto, estes métodos simplificados não são submetidos a revisão à mais de uma década.
Este trabalho apresenta o estudo do efeito do nível de carregamento sobre a resistência ao fogo das lajes mistas de concreto com chapa de aço colaborante a partir de modelos numéricos elaborados com o software ANSYS Mechanical APDL e validados com base em trabalhos experimentais já realizados por outros autores.
Ao todo, 158 simulações foram realizadas e os resultados indicam correlações da resistência ao fogo destas estruturas com base no nível de carregamento e na espessura efetiva das lajes. Junto a isso, é proposto um novo modelo de cálculo para a resistência ao fogo, de lajes mistas com chapa de aço colaborante, segundo o critério de capacidade de carga (R), tendo como variáveis o nível de carregamento e a espessura efetiva das lajes.
Composite slabs with steel decking consist of concrete structures, slabs to be more specific, using its formwork as permanent, turning it part of the structure reinforcement. This technology has been widely used since 1980, and mainly applied on buildings because of its competitive prices and fast application on large scale constructions. The steel frames have an important acting on the mechanical resistance of these structures and when exposed to fire situations it turns into an important component that has to be analysed with more attention thus to its thermal and mechanical properties sensibility on temperature increasing. The European standard EN 1994-1-2 is responsible by the normalization of design and calculation of this kind of structure under fire situations and provide simplified and advanced calculation methods to guarantee the safety of these structures. However, it has not being reviewed for more than one decade. This thesis provide data concerning the effect of the load level on composite slabs with steel decking under fire conditions using numerical models elaborated on software ANSYS Mechanical APDL. The techniques used on modelling are submitted to validation using experimental data obtained on bibliography. The total number of 158 simulations were developed and the results show correlations between the fire resistance of composite slabs and the variables: load level and effective thickness. Yet, a new calculation model is proposed to the fire resistance of composite slabs with steel decking, analysed with the load-bearing criteria (R), taking as variables the load-level and the effective thickness of the slab.
Composite slabs with steel decking consist of concrete structures, slabs to be more specific, using its formwork as permanent, turning it part of the structure reinforcement. This technology has been widely used since 1980, and mainly applied on buildings because of its competitive prices and fast application on large scale constructions. The steel frames have an important acting on the mechanical resistance of these structures and when exposed to fire situations it turns into an important component that has to be analysed with more attention thus to its thermal and mechanical properties sensibility on temperature increasing. The European standard EN 1994-1-2 is responsible by the normalization of design and calculation of this kind of structure under fire situations and provide simplified and advanced calculation methods to guarantee the safety of these structures. However, it has not being reviewed for more than one decade. This thesis provide data concerning the effect of the load level on composite slabs with steel decking under fire conditions using numerical models elaborated on software ANSYS Mechanical APDL. The techniques used on modelling are submitted to validation using experimental data obtained on bibliography. The total number of 158 simulations were developed and the results show correlations between the fire resistance of composite slabs and the variables: load level and effective thickness. Yet, a new calculation model is proposed to the fire resistance of composite slabs with steel decking, analysed with the load-bearing criteria (R), taking as variables the load-level and the effective thickness of the slab.
Description
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Keywords
Lajes mistas Nível de carregamento Resistência ao fogo Modelos numéricos