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Publication
Fire resistance of composite slabs with steel decking and thermal insulation
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Advisor(s)
Abstract(s)
Esta pesquisa é sobre o comportamento termomecânico de lajes mistas aço-concreto com perfis trapezoidais e reentrantes sob condições de incêndio, com ênfase em estratégias de isolamento térmico passivo (proteção de aço e lã mineral) para aprimorar a segurança estrutural e reduzir impactos ambientais. O estudo integrou modelagem numérica bidimensional (ANSYS, Mechanical APDL), com validação usando resultados experimentais (testes em forno em escala real) e a apresentação de uma nova proposta de métodos simplificados para o Eurocódigo 4, visando preencher lacunas normativas relacionadas a geometrias complexas.
As simulações numéricas incorporaram mecanismos não lineares de transferência de calor (condução, convecção, radiação) e consideraram a existência de uma camada de ar entre a chapa de aço e o concreto, resultante da expansão térmica que promove a separação durante os ensaios. A validação do modelo numérico demonstrou concordância com dados experimentais, comprovando a precisão dos modelos. Sistemas com proteção de chapa de aço podem ser utilizados nas nervuras para reduzir significativamente a temperatura na face não exposta, aumentando a resistência ao fogo pelo critério de isolamento térmico (I). Já a lã mineral destacou-se como solução mais eficaz, garantindo maior resistência ao fogo e permitindo redução no consumo de concreto, o que contribuiu para a diminuição de emissões de CO₂.
Para o critério de capacidade estrutural (R), lajes com isolamento passivo mantiveram capacidade resistente superior em comparação a sistemas convencionais, mesmo após exposição prolongada ao fogo ISO 834. A calibração de coeficientes empíricos revisados para o Eurocódigo 4, que incorporaram o efeito de separação (camada de ar) e geometrias não convencionais, melhorou a precisão das previsões termo-estruturais, alinhando métodos analíticos a resultados experimentais.
Concluiu-se que a integração de isolamento térmico passivo e modelagem refinada oferece soluções equilibradas entre segurança contra incêndio, eficiência material e sustentabilidade. Recomenda-se o uso de geometrias otimizadas com isolamento adequado em edifícios de média a alta altura, garantindo resistência ao fogo conforme requisitos normpassivos e reduzindo o impacto ambiental associado à produção de concreto.
This study investigated the thermomechanical behaviour of steel-concrete composite slabs with trapezoidal and re-entrant profiles under fire conditions, with emphasis on passive thermal insulation strategies (steel shields and mineral wool) to enhance structural safety and reduce environmental impacts. The research integrated two-dimensional numerical modelling (ANSYS, Mechanical APDL), numerical validation (real-scale furnace tests), and a presentation of a new proposal to the simplified method in Eurocode 4, aiming to address normative gaps related to complex geometries and air gaps. Numerical simulations incorporated nonlinear heat transfer mechanisms (conduction, convection, radiation) and accounted for an air gap between the steel and concrete, resulting from the thermal expansion verified during the experimental tests. The numerical validation demonstrated agreement with experimental results, confirming model accuracy. Systems with steel shields in the ribs significantly reduced temperatures on the unexposed face, enhancing the fire resistance regarding to insulation criterion (I). Mineral wool proved to be the most effective solution, ensuring prolonged fire resistance and enabling reduced concrete consumption, thereby contributing to lower CO₂ emissions. For the structural capacity criterion (R), slabs with passive insulation maintained superior load-bearing capacity compared to conventional systems, even after prolonged standard ISO834 fire exposure. The calibration of revised empirical coefficients for Eurocode 4, incorporating the air gap effect and non-conventional geometries, improved the accuracy of thermal-structural predictions, aligning analytical methods with experimental results. The study concluded that integrating passive thermal insulation and refined modelling offers balanced solutions between fire safety, material efficiency, and sustainability. The use of optimised geometries with appropriate insulation is recommended for medium to high-rise buildings, ensuring compliance with fire resistance requirements while reducing the environmental impact associated with concrete production.
This study investigated the thermomechanical behaviour of steel-concrete composite slabs with trapezoidal and re-entrant profiles under fire conditions, with emphasis on passive thermal insulation strategies (steel shields and mineral wool) to enhance structural safety and reduce environmental impacts. The research integrated two-dimensional numerical modelling (ANSYS, Mechanical APDL), numerical validation (real-scale furnace tests), and a presentation of a new proposal to the simplified method in Eurocode 4, aiming to address normative gaps related to complex geometries and air gaps. Numerical simulations incorporated nonlinear heat transfer mechanisms (conduction, convection, radiation) and accounted for an air gap between the steel and concrete, resulting from the thermal expansion verified during the experimental tests. The numerical validation demonstrated agreement with experimental results, confirming model accuracy. Systems with steel shields in the ribs significantly reduced temperatures on the unexposed face, enhancing the fire resistance regarding to insulation criterion (I). Mineral wool proved to be the most effective solution, ensuring prolonged fire resistance and enabling reduced concrete consumption, thereby contributing to lower CO₂ emissions. For the structural capacity criterion (R), slabs with passive insulation maintained superior load-bearing capacity compared to conventional systems, even after prolonged standard ISO834 fire exposure. The calibration of revised empirical coefficients for Eurocode 4, incorporating the air gap effect and non-conventional geometries, improved the accuracy of thermal-structural predictions, aligning analytical methods with experimental results. The study concluded that integrating passive thermal insulation and refined modelling offers balanced solutions between fire safety, material efficiency, and sustainability. The use of optimised geometries with appropriate insulation is recommended for medium to high-rise buildings, ensuring compliance with fire resistance requirements while reducing the environmental impact associated with concrete production.
Description
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Keywords
Lajes mistas aço-concreto Resistência ao fogo Eurocódigo 4 Método dos elementos finitos Camada de ar Coeficientes empíricos Redução de CO Resistência ao fogo