Buckling resistance of mono-symmetric steel members : mono-symmetric I-sections and non-prismatic beams, and equal-leg angles subjected to concentric and eccentric compression

• Autor(a) principal: José Onésimo Gomes Junyor
• Data de Publicação: 2023
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UFMG
• Texto Completo: http://hdl.handle.net/1843/63446
• topic: Mono-symmetric beams; Steel angles in compression; Eurocode 3; Stability; General formulation; Engenharia de estruturas; Metais; Vigas; Estabilidade; Modelos matemáticos

This thesis presents a comprehensive study concerning the buckling behaviour of mono-symmetric I-section beams and angle sections in concentric and eccentric compression. The lateral-torsional resistance of prismatic double-symmetric I-section beams is accurately predicted using a mechanically consistent Ayrton-Perry approach, combined with a calibrated generalized imperfection. The corresponding design formulation was recently adopted in the revised version of Eurocode 3. However, for prismatic mono-symmetric I-section beams, the General Case shall be used while for non-prismatic beams only the General Method is available. Both methods present a very large scatter and, in most cases, highly underestimate the lateral-torsional buckling resistance. This work proposes an extension to the General Formulation for non-prismatic beams with arbitrary boundary conditions, partial lateral restraints, and arbitrary loading for mono-symmetric I-sections. Using an advanced numerical model calibrated with experimental test results, a large parametric study is undertaken, and its results are used to assess the available design methodologies and the proposed method. It is concluded that the General Formulation provides excellent safe-sided estimates of the Lateral Torsional Buckling (LTB) resistance, and it is confirmed the weak performance of the General Case and the General Method. Regarding the angle sections under compression, this work presents an extensive advanced numerical study also calibrated with recent experimental results available in the literature on the buckling behavior of hot-rolled steel angles under concentric and eccentric compression. Conclusions may support the ongoing revision in Europe of the design rules for angles concentrically and eccentrically loaded in compression. The numerical results were used for the assessment of existing design procedures commonly applied in practice (Eurocodes and AISC – American Institute of Steel Construction), as well as new recently proposed recommendations. In general, the current analytical rules do not present good agreement with the experimental and calibrated numerical results, even showing unsafe results for some slenderness ranges. In the case of fixed members in eccentric compression, these design rules are extremely conservative, reaching ratios r_N (ratio between numerical and analytical resistances) more than 2. The new proposals resulting from the project ANGELHY present an improved agreement with the numerical results, showing that they may efficiently replace the current design rules in the Eurocodes. However, for concentric compression, a reliability assessment shows that the required partial factor is γ_M1^* = 1.1. Finally, the General Formulation is adapted to angle sections in compression, where once again good performance of the proposed method is observed.