Publicação
In-plane thermo-mechanical behavior of curved steel beams with constant curvature
| Resumo: | Curved steel beams and arches are structures originated from mechanical processes of curving straight members, usually I or H profiles, in order to get a desired geometry to attend aesthetics or project requirements. This type of elements behave differently when compared to regular straight members, with specific instability modes and different responses to various types of loading conditions. For these reasons, such structural members may react distinctively when submitted to fire conditions or elevated temperatures. This paper studies the stability and collapse load of steel curved beams and arches, curved by their major axes, through numerical Finite Element analyses for in-plane buckling at natural and elevated temperatures, simulating a fire event. Firstly, it was developed an analytical method to compute the internal forces based in energy methods for pin-supported arches under two point loads applied at one fourth of the length measured from the supports. Subsequently, linear elastic and nonlinear elasto-plastic buckling and ultimate load analyses were performed at both natural and elevated temperature conditions with the ANSYS Mechanical APDL Finite Element software package, for a variety of span and rise-to-span ratio values, support conditions and steel classes. These results were then compared to critical buckling load formulations found in the literature and to simplified methods presented in Eurocode 3 for elements under bending moments and axial forces. It is seen that support conditions play an important role in the thermo-mechanical response of steel arches, where fixed supports yielded much higher critical load results for every geometry and temperature case. However, even though superior steel classes provide higher resistant loads, regarding responses to thermal loads it was found that support condition is also more significant in this case. Moreover, the standard Eurocode 3 methodology for straight members was compared to the numerical results, which showed a good fit for lower bound loads except for higher slendernesses under elevated temperatures, where numerical solutions yielded result points under the standard resistance curves. Also, an analytical and experimental study on the cold-curving process of straight steel beams into arches using point loads was conducted, aiming to analytically define a post-curving residual stress profile and investigate the influence of elastic springback in the final shape of an arch. |
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| Autores principais: | Souza, Jean Marcos Teixeira de |
| Assunto: | Curved beams Arches Steel Temperature Finite element method |
| Ano: | 2021 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Instituto Politécnico de Bragança |
| Idioma: | inglês |
| Origem: | Biblioteca Digital do IPB |
| Resumo: | Curved steel beams and arches are structures originated from mechanical processes of curving straight members, usually I or H profiles, in order to get a desired geometry to attend aesthetics or project requirements. This type of elements behave differently when compared to regular straight members, with specific instability modes and different responses to various types of loading conditions. For these reasons, such structural members may react distinctively when submitted to fire conditions or elevated temperatures. This paper studies the stability and collapse load of steel curved beams and arches, curved by their major axes, through numerical Finite Element analyses for in-plane buckling at natural and elevated temperatures, simulating a fire event. Firstly, it was developed an analytical method to compute the internal forces based in energy methods for pin-supported arches under two point loads applied at one fourth of the length measured from the supports. Subsequently, linear elastic and nonlinear elasto-plastic buckling and ultimate load analyses were performed at both natural and elevated temperature conditions with the ANSYS Mechanical APDL Finite Element software package, for a variety of span and rise-to-span ratio values, support conditions and steel classes. These results were then compared to critical buckling load formulations found in the literature and to simplified methods presented in Eurocode 3 for elements under bending moments and axial forces. It is seen that support conditions play an important role in the thermo-mechanical response of steel arches, where fixed supports yielded much higher critical load results for every geometry and temperature case. However, even though superior steel classes provide higher resistant loads, regarding responses to thermal loads it was found that support condition is also more significant in this case. Moreover, the standard Eurocode 3 methodology for straight members was compared to the numerical results, which showed a good fit for lower bound loads except for higher slendernesses under elevated temperatures, where numerical solutions yielded result points under the standard resistance curves. Also, an analytical and experimental study on the cold-curving process of straight steel beams into arches using point loads was conducted, aiming to analytically define a post-curving residual stress profile and investigate the influence of elastic springback in the final shape of an arch. |
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