Percorrer por autor "Real, Paulo Vila"
A mostrar 1 - 3 de 3
Resultados por página
Opções de ordenação
- Accuracy of 2D numerical models towards the prediction of the fire resistance on LSF partition wallsPublication . Piloto, P.A.G.; Gomes, Stephan; Torres, Leonardo; Couto, Carlos; Real, Paulo VilaLightweight steel framing (LSF) walls are commonly used in modern buildings due to their high strength-to -weight ratio and readiness for installation. However, empty cavities within these walls can pose a fire risk if not properly addressed. In order to ensure the fire resistance and performance of LSF walls with empty cavities, various modelling techniques can be employed. Two-dimensional thermal models can also be used to simulate the behaviour of LSF walls with empty cavities in a fire scenario. These models can predict the spread of heat through the empty cavity, allowing designers to identify potential fire hazards and make adjustments to the design to mitigate those risks.Three different computational solution methods were used to compare the fire performance of LSF walls with void cavities. Solution method 1 considers the air-structure interaction in the cavity region. Solution method 2 considers the existence of interface elements for the radiation heat transfer in the cavity region allowing the cavity temperature prediction. Solution method 3 considers the convection and radiation in the cavity region with a prescribed cavity temperature from experiments (hybrid). Solution methods 1 and 3 give a small root mean square error (RMSE), when compared with solution method 2. Solution method 3 gives a better approx-imation because can capture the main fire events during the fire, such as the cracks and fall off. Based on the parametric study, a new proposal is presented to predict the fire resistance by insulation, depending on the gypsum type and thickness.
- Bending resistance of austenitic stainless steel hollow sections at elevated temperaturesPublication . Piloto, P.A.G.; Mesquita, L.M.R.; Cruz, Áureo A.T.; Lopes, Nuno; Arrais, Flávio; Real, Paulo VilaThe present research aims to increase the knowledge of the structural behaviour of stainless steel members under fire. Eight experimental bending tests at elevated temperatures (500, 700 ºC) built with RHS 150×100×3 austenitic stainless-steel beams, using two different grades (1.4301, 1.4571) also known as 304 and 316Ti, are presented. Both grades 1.4301 (X5CrNi18–10) and 1.4571 (X6CrNiMo17–12–2) have almost the same core chemical composition but there are some differences, especially the grade 1.4571 has 2–2.5% molybdenum and a small amount of titanium (less than 0.7%). Grade 1.4301 presents good rust resistance, sufficient acid resistance and good weldability, while grade 1.4571 presents very good rust resistance, very good acid resistance and also good weldability. Both have almost the same strength, but grade 1.4571 has superior strength at elevated temperatures. Both material grades were experimentally characterised with coupon tensile tests at room temperature. The load-displacement behaviour is validated with 3D shell finite element models, assuming a true stress-strain material model, based on the two-stage Ramberg Osgood constitutive law. With the developed numerical model, a parametric analysis is presented to study the fire resistance of beams from both materials, using three different cross-sections and eleven different temperatures. The bending resistance obtained with the finite element model is in good agreement with the cross-sectional design moment resistance, when considering the effective area, confirming that the design rules from EN1993–1–2 are safe for less slender cross-sections and unsafe for the most slender cross-sections.
- Fire resistance of austenitic stainless steel beams with rectangular hollow sectionsPublication . Lopes, Nuno; Arrais, Flávio; Real, Paulo Vila; Alves, Matheus Henrique; Mesquita, L.M.R.; Piloto, P.A.G.; Pinho-da-Cruz, JoaquimThis paper presents a study on the structural behaviour of stainless steel profiles under fire conditions. An experimental campaign of three-point bending tests on rectangular hollow section beams of the grade 1.4301 (also known as 304) were conducted, considering both steady-state and transient state conditions. Prior to those tests, the mechanical characterization of the stainless steel was investigated. The constitutive laws obtained by tensile tests at high temperatures are compared with those recommended in Eurocode 3, whose respective material models were recently proposed for modifications, still requiring complete validation. In addition, numerical modelling of the bending tests has been performed afterwards achieving close approximation to the observed experimental results. Finally, analytical methods to predict the load-deflection behaviour are also presented. Good agreement between the considered methodologies was attained validating their application on the prediction of the fire behaviour of stainless steel beams.