Finite element analysis of steel beams with web apertures under fire condiction

This 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.info:eu-repo/semantics/publishedVersio

Finite element analysis of steel beams with web apertures under fire condiction

This 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.info:eu-repo/semantics/publishedVersio

Behaviour of cellular beams protected with intumescent coatings

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.info:eu-repo/semantics/publishedVersio

Investigation of residual stresses on the fire resistance of unrestrained cellular beams

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.info:eu-repo/semantics/publishedVersio

Behaviour of cellular steel beams at ambient and high-temperature conditions

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.The Ministry of Higher Education and Scientific Research, MESRS, of Algeria, is gratefully acknowledged for the PhD grant funding support: ref. 714/PNE/Doctorant/Portugal/2019-2020.info:eu-repo/semantics/publishedVersio

Intumescente fire protection of cellular beams

Cellular beams are structural steel beams that are deeper than normal rolled sections and have holes cut into their webs. As the web post failure may occur before the section reaches the limiting temperature usually an increase in the fire protection may be required for members with web openings in comparison to its equivalent solid section. The aim of this work is to present an experimental study of unloaded solid and cellular beams with circular holes in fire conditions with and without intumescent fire protection. These preliminary tests are the basis for generating an elemental multi-temperature analysis (EMTA) needed to assess cellular beams with intumescent protection as prescribed by the prEN13381- 9

Simulation numerique du comportement non-lineaire des portiques métalliques en situation d’incendie

Pour des raisons pratiques d’exploitation et de durabilité, les bâtiments industriels, sont dans la majorité des cas conçu en charpente métallique. 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 bâtiments industriels. L’objectif de ce travail concerne l’étude du comportement non-linéaire des structures industrielles en acier selon plusieurs scénarios de feu. L’analyse numérique par la MEF et utilisant le logiciel ANSYS est considérée afin d’évaluer la résistance de ces structures et d’optimiser 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

On the behaviour of structural steel beams under natural compartment fire

Fire is an extreme action, to which a steel structure may be submitted, and therefore, must be designed to resist. Traditionally, the fire resistance of structural steel beams has been determined in standard fire tests, with the temperature-time curveISO834representing more severe heating conditions compared to that which occurs in many typical natural fire compartments.Thereforeto design a steelstructure safely and economically, it is necessary to calculate temperature distribution in steel beamsunder natural fire. In this paper, the temperature profiles in a steel beams under natural fire arestudied first, using spread-sheets written by authorsand compared to standard fire. Secondly, twoCardington compartment corner office tests are highlighted,and analysis of primary and secondary steel beamsis presented.Simple theoretical natural fire models based on Eurocode EN 1991-1-2 parametric compartment fire are used and a comparison is made using the experimental results from tests conducted at Cardington research centre, UK. Compartment temperatures and cross-section temperature distribution respectively demonstrates that analytical fire models and experimental results are in good agreement in the case of timber cribs fire load

Finite element investigation on the behaviour of structural steel beams subjected to standard & parametric fire

This 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.info:eu-repo/semantics/publishedVersio

Etude par simulation numérique du comportement des portiques métalliques en situation d’incendie

Les 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 3info:eu-repo/semantics/publishedVersio