Browsing by Author "Kada, Abdelhak"
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- Behaviour of cellular beams protected with intumescent coatingsPublication . Lamri, Brahim; Mesquita, L.M.R.; Kada, Abdelhak; Piloto, P.A.G.A new engineering practice in modern buildings is to use beams with web openings to allow the passage of services within the depth of the beam instead of underneath the beam. This helps to reduce the floor height of the building and optimises the available space. The openings are cut in the web of a beam or a beam profile cut and re-welded to form the so called cellular beam. Usually the bending resistance is increased, in comparison to the original solid section, but the failure mode occurs generally at lower critical temperatures. The failure mode in fire is related to the distance between holes, web post slenderness in addition to the web and flange section factor. The loss of the beam strength with temperature promotes an early web post failure that occurs before the section reaches the critical temperature, reason why an increase in the fire protection may be required for these beams to achieve the same fire resistance time as the equivalent solid beams. Recent research on beams with closely spaced web openings has shown that the web posts between adjacent openings become significantly hotter than the bottom flange of the section, and that web post buckling can often be the failure mode for a member in the fire condition. The present study aims at investigating the behaviour of cellular beams under fire conditions when considering unprotected and intumescent protected cellular steel beams. Experimental tests are conducted in both cases with and without protection where temperature profiles are produced and analysed. The behaviour of the intumescent fire protection with different properties and thicknesses is studied and compared using fire resistance tests. Simplified method of analysis and finite element models are used to study and compare results from tests. The experimental temperature results show intumescent coating efficiency when applied to solid beams and also for cellular beams, resulting from its application an increase fire the resistance time in both cases. Considering for example the time required for the steel to reach 550 [ºC], with the application of a nominal thickness of 1000 [m], an increase of the fire resistance time of 25 minutes is achieved for solid beams, while for cellular beams with a hole diameter of 160[mm] the increase is equal to 17 minutes. Tests performed in cellular beams with web posts of 80 and 100 [mm] does not show any significate temperature difference neither in relation to the fire resistance time. For both beams, when is applied a nominal DFT equal to 1000 [m], the temperature of 550 [ºC] is achieved after 28 minutes. For longer fire exposure periods a slight difference can be already verified. For the case of a cellular beam with intumescent coating, test P16, a small contraction of the intumescent char around the circular hole, leaving a small area of steel directly exposed to fire. This study is being extended to a wider parametric analysis considering different cellular beams geometries and intumescent coatings thicknesses to allow for a general elemental multi-temperature analysis (EMTA).
- Behaviour of cellular beams protected with intumescent coatingsPublication . Brahim, Lamri; Mesquita, L.M.R.; Kada, Abdelhak; Piloto, P.A.G.A new engineering practice in modern buildings is to use beams with web openings to allow the passage of services within the depth of the beam instead of underneath the beam. This helps to reduce the floor height of the building and optimises the available space. The openings are cut in the web of a beam or a beam profile cut and re-welded to form the so called cellular beam. Usually the bending resistance is increased, in comparison to the original solid section, but the failure mode occurs generally at lower critical temperatures. The failure mode in fire is related to the distance between holes, web post slenderness in addition to the web and flange section factor. The loss of the beam strength with temperature promotes an early web post failure that occurs before the section reaches the critical temperature, reason why an increase in the fire protection may be required for these beams to achieve the same fire resistance time as the equivalent solid beams. Recent research on beams with closely spaced web openings has shown that the web posts between adjacent openings become significantly hotter than the bottom flange of the section, and that web post buckling can often be the failure mode for a member in the fire condition. The present study aims at investigating the behaviour of cellular beams under fire conditions when considering unprotected and intumescent protected cellular steel beams. Experimental tests are conducted in both cases with and without protection where temperature profiles are produced and analysed. The behaviour of the intumescent fire protection with different properties and thicknesses is studied and compared using fire resistance tests. Simplified method of analysis and finite element models are used to study and compare results from tests.
- 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.
- 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.
- 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 analysis of steel beams with web apertures under fire condictionPublication . Kada, Abdelhak; Lamri, B.; Mesquita, L.M.R.; Bouchair, AbdelhamidThis work is intended to analyse the behaviour steel beams with apertures under high temperatures rise due to fire using finite elements simulations with ANSYS software. It includes a structural fire analysis and a comparative study of cellular and castellated steel beams which takes into account transient temperature effect, material and geometric non-linear behaviour. FE models which estimate limiting time, mid-span deflection and failure temperature are presented for hexagonal and circular types of web opening shapes under several uniform load levels. The study shows that for any beam with closely spaced openings failure in fire will in most cases be caused by failure of the steel web. The numbers of web-openings and cells as well as their shapes are critical for the behaviour of castellated sections and cellular beams under fire condition.
- 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.
- Fire after earthquake assessment of 3D reinforced concrete structuresPublication . Haouach, Ismail; Kada, Abdelhak; Lamri, Belkacem; Piloto, P.A.G.Despite that, an earthquake’s occurrence can lead to dramatic effects with significant damage in urban areas, including human and material losses. Fire after an earthquake amplifies the overall impact and becomes a catastrophic event. Most constructions in Algeria are made of reinforced concrete, and current regulations overlook fires after earthquakes. Structural designs are inadequate to handle such events. This study aims to investigate the behaviour of 3D reinforced concrete frames, as part of a residential building, designed according to internal codes, CBA93 and RPA99 v2003. This 3D RC structure is exposed to several load levels of its vertical load bearing capacity. The structural system is assumed to undergo seismic scenarios characterised by various levels of story drift and damage level types. The structure is then exposed to the standard fire ISO834 model. Numerical investigations are carried out for thermo-mechanical analysis using the finite element software ANSYS, taking into account geometric and material non-linearities. Results highlight the significant impact of vertical loads, story drifts, fire scenarios, and structural damage on a building’s response to fire following an earthquake. These factors collectively influence the collapse probabilities, underlining the importance of holistic risk assessment in structural design.