Percorrer por autor "Silva, Luana Vidoti da"
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- Comportamento ao fogo de vigas alveolares com aberturas circularesPublication . Silva, Luana Vidoti da; Mesquita, Luís M.R.; Piloto, Paulo A.G.; Ferreira, Débora; Barreira, Luísa; Lopes, Nuno; Couto, Carlos; Vila Real, PauloO comportamento de vigas alveolares de aço à flexão, especialmente em situação de incêndio, foi investigado através de uma campanha experimental e da validação de um modelo numérico. Os resultados demonstram que o modelo de elementos finitos prevê com boa precisão a capacidade de carga e os modos de falha observados nos ensaios. A análise evidencia que a geometria das aberturas condiciona o modo de colapso à temperatura ambiente, enquanto o aumento da temperatura pode alterar o mecanismo de falha para uma mesma geometria, promovendo o colapso por encurvadura do montante da alma ou pelo Mecanismo de Vierendeel. A investigação apresenta dados experimentais relevantes e um modelo numérico validado, essenciais para o desenvolvimento de futuras regras de dimensionamento.
- Elastic lateral-torsional buckling of cellular beamsPublication . Silva, Luana Vidoti da; Mesquita, L.M.R.Cellular beams are I-shaped steel sections with advantages provided by their circular web openings. This type of beam can have greater spans, be more slender and higher than the solid beams, being more prone to failure by lateral-torsional buckling. Given there is still no specific standard for cellular beams and owing to the importance of safety verification, this paper numerically investigated the lateral-torsional buckling of these beams. Considering the torsional constant as the most important parameter in the design of web-opening beams, this study proposes a new torsional constant and approaches four different calculation methods of weighted average torsional constants. The elastic critical moment of cellular beams was numerically modelled using ANSYS software and compared with analytical results according to European standards, varying the torsional constants. The weighted average torsional constant based on an equivalent area and using the proposed torsional constant was the most efficient, showing the best analytical results when compared with the numerical ones considering the load condition of constant bending moment. Furthermore, from all the geometric parameters evaluated, the height of the cellular beam was what most influenced the elastic critical moment of the cellular beams.
- Experimental investigation of cellular steel beams at ambient and elevated temperaturesPublication . Silva, Luana Vidoti da; Giacomitti, Nickolas; Ferreira, Débora; Lopes, Nuno; Mesquita, Luís M.R.Cellular steel beams, commonly used in modern construction, exhibit complex failure mechanisms that have not been thoroughly explored, especially under fire conditions. This research investigates the structural behaviour of cellular beams under both ambient and elevated temperatures, with a focus on load-bearing capacity and failure modes. Experimental tests were conducted on a solid beam and six cellular beams with varying hole spacings and diameters at different temperatures. All beams were tested under three-point bending, subjecting the openings and the web posts to different combinations of bending moments and shear forces. Experimental maximum loads and failure modes are compared with the design method of EN1993-1-13 and EN1993-1-2. At ambient temperature, failure modes varied with beam design: specimens with smaller opening spacings failed by web-post buckling, while larger openings resulted in a Vierendeel mechanism. While the Eurocode predictions for load capacity were conservative under ambient conditions, the design model did not accurately predict the correct failure mode. Elevated temperatures significantly reduced the load capacity and, in some cases, changed the collapse mechanism. These results highlight that current design rules are unreliable in predicting the failure mode and may not ensure safety at higher temperatures, stressing the need for specific design rules for cellular beams in fire conditions.