Percorrer por autor "Lamri, Belkacem"
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- Behaviour of cellular steel beams at ambient and high-temperature conditionsPublication . Oribi, Sabrina Benyettou; Kada, Abdelhak; Lamri, Belkacem; Mesquita, L.M.R.New developments in building construction have been observed to attain sustainable design criteria and the efficient use of raw materials, as steel is an example. This led to an increase in recent research on the optimization of geometric configurations of web-opening steel sections to meet cost-effectiveness in structural design. Improvement of the design method for perforated unrestrained steel beams to assess their behaviour under lateral torsional buckling (LTB) is still an ongoing issue for scientists and designers alike. In this article, cellular beams bound to instability were studied analytically by Eurocode and numerically by the finite element method to investigate their behaviour at ambient and elevated temperatures due to fire. The analysis encompasses the effect of the coupling and the endplates' thickness on the cellular beams' collapse strength considering the initial geometric imperfections and material nonlinearities. A parametric study including changing temperature, crosssection geometry, and web aperture configurations was done for beams subjected to uniform bending and distributed load. The analyses depicted the following failure modes: LTB and LTB+ plastification of the two Tsection (P-2 T) for end moment load and yielding of top tee section's flange (B-1 T), P-2 T, web post-buckling (WPB), Vierendeel mechanism (VM) and LTB for a distributed load. Combined failure modes such as LTB + WPB, LTB + VM and LTB + VM + WPB have also been observed. Buckling curves for cellular beams were assessed by comparing FE reduction factors with those of the buckling curve recommended by Eurocode 3 for equivalent solid steel beams. A new proposed formula for the plateau length of the LTB curves was obtained, based on the mean squared error method (MSE) between the numerical results and Eurocode formulae. The comparison between the numerical and the simplified design method predicted results shows that the proposed formulae have reduced the discrepancy and improved the LTB curve to better assess the cellular beams behaviour.
- Cellular slabs with and without insulation submitted to fire conditionsPublication . Haddad, Djaafer; Lamri, Belkacem; Fonseca, E.M.M.The wooden cellular slabs are lightweight structures, easy to assemble, and with excellent architectural features, as good thermal and acoustic conditions. The wooden cellular slabs with perforations are typical and very common engineering solutions, used in the ceiling or flooring to improve the acoustic absorption of compartments, and also have a good insulation and relevant architectonic characteristics. However, the high vulnerability of wooden elements submitted to fire conditions requires the evaluation of its structural behaviour with accuracy. The main objective of this work is to present a numerical model to assess the fire resistance of wooden cellular slabs with different perforations. Also the thermal behaviour of the wooden slabs will be compared considering material insulation inside the cavities. The time-temperature history and the residual cross-section of wooden slabs were numerically measured and analysed.
- Computational model for W-W-W connections at ambient and high temperaturesPublication . Aissa, Abderrahim; Fonseca, E.M.M.; Lamri, BelkacemThe aim of this work is to present an approach for wood‐wood‐wood (W‐W‐W) connections design in double shear at ambient and high temperatures, using dowelled connectors. For each situation, all calculations will be performed to determine the cross‐section and the number of fasteners. A procedure will be presented to calculate the load carrying capacity per shear plane and per steel fastener, using a glued laminated in birch W‐W‐W timber GL28h.
- Computational model for W-W-W connections at ambient and high temperaturesPublication . Aissa, Abderrahim; Fonseca, E.M.M.; Lamri, BelkacemThe use of wood, as a structural material, continues to grow far beyond traditional application. Timber connections are considered critical due to their resistance and durability, mainly depend on the join design of the different structural elements. They are subjected to localized stresses and strains, and may expose the overall stability of the structure. For imposed thermal loads under fire conditions, it remains important to improve the knowledge of the connection behaviour.
- Etude par simulation numérique du comportement des portiques métalliques en situation d’incendiePublication . Benlakehal, Nourredine O.; Lamri, Belkacem; Kada, Abdelhak; Mesquita, L.M.R.; Bouchair, AbdelhamidLes structures en portiques métalliques à double versants sont largement utilisées dans les bâtiments industriels pour des raisons pratiques d’exploitation, de durabilité et de rentabilité. Cependant le matériau acier quoi que ductile, il reste vulnérable aux excès de températures. Les récents événements d’incendies concernant les structures et bâtiments industriels de Sonatrach, à Alger dans une zone urbaine ou à Skikda dans une zone industrielle, nous rappellent le danger réel et le risque potentiel des incendies. Les nouvelles normes Européennes définissent des exigences actives et passives concernant le comportement au feu des hangars industriels. L’objectif de ce travail est d’étudier, par des simulations numériques, le comportement des portiques métalliques à double versants sous différents scénarios d’incendie. L’analyse numérique par la MEF et utilisant le logiciel ANSYS est considérée afin d’évaluer la résistance de ces structures et de rationaliser leur protection au feu. Une analyse, utilisant les non linéarités géométrique et matérielle, est conduite avec une variation progressive des températures jusqu’à la ruine. Différents taux de chargement ainsi que différents scénarios de feu seront utilisés pour évaluer la température critique ainsi que les déplacements des portiques en fonction de l’évolution de la température. Les résultats du modèle numérique sont comparés à ceux calculés par les méthodes simplifiées de l’Eurocode 3
- Finite element investigation on the behaviour of open-web steel beams subjected to firePublication . Kada, Abdelhak; Lamri, Belkacem; Bouchair, Abdelhamid; Mesquita, L.M.R.This paper presents a numerical investigation on the behaviour of open-web steel beams under high temperatures rise due to fire using finite elements simulations with ANSYS software. Cases of study for solid parent steel elements as well as castellated and cellular beams are considered and take into account uniform and transient temperature rise, material and geometric non-linear behaviour. Input fire is the standard temperature-time curve ISO834 fire model and thermal and mechanical analyses are done using the effect of temperature dependent material properties according to Eurocode3 part1--2 recommendations for mechanical steel properties reduction. FE models which estimate failure temperatures are presented for two most commonly used types of web opening shapes including, hexagonal and circular for simply supported beams under uniformly distributed mechanical loading. The study shows that the numbers of web-openings and cells as well as their shapes are critical for the behaviour of castellated steel beams under fire conditions. Results are related to temperature profiles in steel beam cross-sections, variation of displacements with respect to temperature change and critical temperatures.
- Finite element investigation on the behaviour of structural steel beams subjected to standard & parametric firePublication . Kada, Abdelhak; Lamri, Belkacem; Benlakehal, Nourredine O.; Mesquita, L.M.R.; Bouchair, AbdelhamidThis paper intends to present an investigation of the behaviour of steel beams under high temperatures rise due to fire using finite elements simulations with ANSYS software. Cases of study for solid as well as open web beams are considered and take into account uniform and transient temperature rise, material and geometric non-linear behaviour. Input fire scenarios are standard temperature-time curve ISO834 and parametric compartment fire model based upon Eurocode EN 1991-1-2. For the latter a comparison is made using the experimental results from BRE-Cardington tests data. Thermal and mechanical analysis is done using the effect of temperature dependent material properties and the Eurocode recommendations in estimating reduction mechanical steel properties. Three types of cellular beams are studied and the number of cells is shown to be critical for their behaviour under fire conditions. Results are related to temperature profiles in steel beam cross-sections, variation of displacements with respect to temperature change and critical temperatures.
- Finite-element analysis for the performance of steel frames under fire after earthquakePublication . Merouani, Mohammed Redha; Kada, Abdelhak; Lamri, Belkacem; Piloto, P.A.G.Recent events of fire after an earthquake (FAE) show that this is a frequent dual event leading to a significant loss which can only be reduced by increasing the level of safety. This paper presents numerical models developed for FAE analyses on 24 steel portal frames to investigate their behaviour and estimate the performance in terms of ratios with regard to horizontal displacement, fire resistance time, and critical temperature. In this study, validated numerical models are used for a parametric study to explore the effect of number of bays and stories on the performance of steel frames under two fire scenarios. Frames with one bay and one story are designed with the Algerian seismic code, RPA99v2003, considering the seismic region of Chlef and other frames are checked with Eurocode for the ultimate limit state. All frames subjected to the seismic and the ISO834 fire actions are simulated within a single software, ANSYS, for pushover and thermo-mechanical analyses. The performance is evaluated, by FAE analysis for damaged frames remaining in the plastic state and undamaged frames not reaching the plastic state, and compared to those subjected to fire without earthquake (FWoE). The frames under FAE are more vulnerable to fire and increasing damage is produced and hence reducing their structural performance. The results also show that the higher the number of bays is, the higher the performance of the frames. The critical temperature of beams decreases with the beam length. The frames with FAE, under inelastic conditions, have smaller fire resistance, when compared to undamaged frames.
- Investigation of residual stresses on the fire resistance of unrestrained cellular beamsPublication . Oribi, Sabrina Benyettou; Kada, Abdelhak; Lamri, Belkacem; Mesquita, L.M.R.It is being a common engineering practice to use steel beams with web openings in buildings requiring long spans, besides giving an important additional advantage of allowing services through instead of underneath the beams. The presence of these openings is penalizing the carrying capacity at ambient temperature and in the case of fire due to large cells and double nonlinearity geometric and material a complex behaviour take place. In this study, numerical models for beams having closely spaced large openings are simulated with ISO834 fire loading including both nonlinearities cited above in the primal investigation. Followed as a second investigation, is the effect of residual imperfections added to the numerical model mentioned above and simulated for different diagrams as presented within updated literature. All simulations were done using the finite element software ANSYS, to analyse the results captured for lateral torsional buckling (LTB) behaviour in terms of vertical and lateral displacement, von Mises stresses for different sections at ambient and fire conditions. For this parametric study, the change in cross-section geometries, opening spacing, beam length on the LTB of cellular beams is analysed.
- Mechanical analysis of a portal steel frame when subjected to a post-earthquake firePublication . Merouani, Mohammed Redha; Lamri, Belkacem; Kada, Abdelhak; Piloto, P.A.G.Fire or earthquake pose a significant threat to the human life, and cause an enormous damage to the structures, moreover the dual effect of a Post-Earthquake Fire (PEF) is a major hassle to designers and rescuers alike. Designers, when considering Algerian seismic rule (RPA99v2003) [1], ignore the possibility of a post-earthquake fire, whose effect can lead to the dramatic collapse of the structures.