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As ligações em madeira são partes muito importantes de uma estrutura, sendo
responsáveis por garantir a resistência e estabilidade estrutural. O presente trabalho tem como
objetivo avaliar o comportamento mecânico e térmico de ligações aço-madeira (W-S-W) com
chapa metálica central e ligadores do tipo cavilha metálica em corte duplo. Para o projeto das
ligações W-S-W foram utilizadas as regras normativas com base no Eurocódigo 5-1-1 (CENEN1995-
1-1, 2004) e Eurocódigo 5-1-2 (CEN-EN1995-1-2, 2004). Posteriormente foram
desenvolvidos modelos computacionais das ligações em corte duplo e sob o efeito de altas
temperaturas.
Foram projetadas diversas ligações (W-S-W) atendendo às diferentes variáveis
consideradas: cinco cargas de tração, membros em madeira com duas espessuras diferentes e
dois diâmetros diferentes de cavilha. Foram utilizadas as propriedades da madeira laminada
colada da classe GL28h da espécie “birch wood”, seguindo os valores prescritos no Eurocódigo
5 para a resistência e rigidez à temperatura ambiente e a elevadas temperaturas.
O modelo computacional utiliza o método dos elementos finitos (MEF), através de uma
análise estrutural com carga incremental, algoritmo de contato entre os diferentes elementos da
ligação, propriedades dos materiais ortotrópicas para a madeira e isotrópicas para o aço, para
o cálculo da máxima capacidade resistente da ligações à temperatura ambiente.
O modelo computacional térmico, baseado no MEF, permite uma análise em regime
transiente e utilização das propriedades térmicas não-lineares dos materias envolvidos, para o
cálculo da velocidade de carbonização na madeira e do campo de temperaturas, nas mesmas
ligações protegidas e não-protegidas, mas agora expostas ao fogo para um lado ou três dos seus
lados. Neste tipo de análise, os ligadores tiveram uma forte influência na avaliação da
resistência térmica. As ligações com proteção mostraram também um bom desempenho.
Os resultados mostraram que o modelo numérico apresenta boa concordância com o
modelo analítico, sendo o maior erro obtido entre os métodos 15,40%, concluindo-se que nas
mesmas condições o arranjo dos ligadores pode aumentar significativamente a capacidade de
carga resistente da ligação. Na análise térmica os valores obtidos no cálculo da velocidade de
carbonização foram maiores que os apresentados no Eurocódigo 5, com maior variação nas
regiões próximas às cavilhas.
Timber connections, responsible for ensuring structural strength and stability, are very important parts of a structure. The main objective of the present work is to evaluate the mechanical and thermal behaviour of steel-wood connections (W-S-W) with central steel plate and dowel steel connectors in double-shear. For the design of W-S-W connections, the normative rules based on Eurocode 5-1-1 (CEN-EN1995-1-1, 2004) and Eurocode 5-1-2 (CEN-EN1995-1-2, 2004) were used. In adition, computational models were developed for the double-shear conections for mechanical and thermal analysis due the effect of high temperatures. Several connections (W-S-W) were designed taking into account different variables: five tensile loads, wood members with two different thicknesses and two different dowel diameters. The properties of GL28h glued laminated wood of the "birch wood" specie were used, following the values prescribed in Eurocode 5 for strength and stiffness at room and high temperatures. The advanced model uses the finite element method (FEM), through structural analysis with incremental load, contact algorithm between different elements of the connection, properties of orthotropic materials for wood and isotropic for steel, for the calculation of maximum load-carrying capacity at room temperature. The thermal computational model, based on FEM, allows a transient analysis and uses nonlinear thermal properties of the involved materials, for charring layer calculation in the wood material and temperature field for protected and unprotected connections. The conections in study were exposed to the fire conditions at one or three sides. In this type of analysis, the dowels had a strong influence on the thermal resistance evaluation. Connections with protection also showed good performance. The numerical results have a good agreement with the analytical model, being the obtained major error among the methods is 15.40%, concluding that under the same conditions the dowels arrangement can significantly increase the load-carrying capacity. In the thermal analysis, the obtained values for charring layer calculation were higher when compared with Eurocode 5, with greater variation near of the holes dowels.
Timber connections, responsible for ensuring structural strength and stability, are very important parts of a structure. The main objective of the present work is to evaluate the mechanical and thermal behaviour of steel-wood connections (W-S-W) with central steel plate and dowel steel connectors in double-shear. For the design of W-S-W connections, the normative rules based on Eurocode 5-1-1 (CEN-EN1995-1-1, 2004) and Eurocode 5-1-2 (CEN-EN1995-1-2, 2004) were used. In adition, computational models were developed for the double-shear conections for mechanical and thermal analysis due the effect of high temperatures. Several connections (W-S-W) were designed taking into account different variables: five tensile loads, wood members with two different thicknesses and two different dowel diameters. The properties of GL28h glued laminated wood of the "birch wood" specie were used, following the values prescribed in Eurocode 5 for strength and stiffness at room and high temperatures. The advanced model uses the finite element method (FEM), through structural analysis with incremental load, contact algorithm between different elements of the connection, properties of orthotropic materials for wood and isotropic for steel, for the calculation of maximum load-carrying capacity at room temperature. The thermal computational model, based on FEM, allows a transient analysis and uses nonlinear thermal properties of the involved materials, for charring layer calculation in the wood material and temperature field for protected and unprotected connections. The conections in study were exposed to the fire conditions at one or three sides. In this type of analysis, the dowels had a strong influence on the thermal resistance evaluation. Connections with protection also showed good performance. The numerical results have a good agreement with the analytical model, being the obtained major error among the methods is 15.40%, concluding that under the same conditions the dowels arrangement can significantly increase the load-carrying capacity. In the thermal analysis, the obtained values for charring layer calculation were higher when compared with Eurocode 5, with greater variation near of the holes dowels.
Descrição
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Palavras-chave
Ligação W-S-W Madeira Aço Capacidade de carga Carbonização