Failure temperature of a System Comprising a Restrained Column Submitted to Fire

The problem of columns submitted to fire is discussed in the intoduction with an emphasis on the differences between the case of a column acting as a single element or being part of a frame. In the latter case, failure of the column does not necessarily lead to the failure of the structure. The basic principles of the arc-length technique are given, first for the way it is applied traditionally at room temperature, then for the way it can be applied to extend a numerical simulation beyond the moment of local failures in case of fire. The technique is then applied to the case of restrained columns and it is shown how it is possible to obtain a safe estimate of the critical temperature of the column leading to the failure of the structure, even if the degree of restraint apllied to the column is unknown

Implementation of a weak coupling approach between a CFD and an FE software for fires in compartment

The paper presents the assumptions and the issues that arise when developing an integrated modelling methodology between a Computational Fluid Dynamics (CFD) software applied to compartment fires and a Finite Element (FE) software applied to structural systems subjected to fire. In particular, a weak coupling approach used to simulate a fire exposed structure by modelling the fire development in the compartment, the heat penetration in the structure and the mechanical response is described. The advantages and the disadvantages of such a technique are highlighted compared to a full coupling that conversely takes into account all mutual interactions. The favourable aspect of computing the thermal response of the structure in the FE model in order to avoid modelling the structure in the CFD model is underlined, namely a sensitive reduction of computational demand. Finally, the study is enriched by an application of this methodology that concerns the simulation of a pool fire in an open compartment the results of which are compared with those obtained by employing the simplified Hasemi model included in the Eurocodes

Lateral Torsional Buckling of Steel I-Beams in Case of Fire – Numerical Modelling

peer reviewedaudience: researche

Experimental Tests and Numerical Modelling on Slender Steel Columns at High Temperatures

Purpose The purpose of this paper is to gain from experimental tests an insight into the failure mode of slender steel columns subjected to fire. The tests will also be used to validate a numerical model. Design/methodology/approach A series of experimental fire tests were conducted on eight full-scale steel columns made of slender I-shaped Class 4 sections. Six columns were made of welded sections (some prismatic and some tapered members), and two columns were made of hot rolled sections. The nominal length of the columns was 2.7 meters with the whole length being heated. The load was applied at ambient temperature after which the temperature was increased under constant load. The load was applied concentrically on some tests and with an eccentricity in other tests. Heating was applied by electrical resistances enclosed in ceramic pads. Numerical simulations were performed with the software SAFIR® using shell elements. Findings The tests have allowed determining the appropriate method of application of the electrical heating system for obtaining a uniform temperature distribution in the members. Failure of the columns during the tests occurred by combination of local and global buckling. The numerical model reproduced correctly the failure modes as well as the critical temperatures. Originality/value The numerical model that has been validated has been used in subsequent parametric analyses performed to derive design equations to be used in practice. This series of test results can be used by the scientific community to validate their own numerical or analytical models for the fire resistance of slender steel columns.FIDESC

Improvement of the Parametric Fire of Eurocode 1 based on Experimental Tests Results

peer reviewedThe basic equations, the limitations and the main features of the parametric fire proposed in Annexe B of Eurocode 1 are given. 48 experimental fire tests are used to assess the validity of this model. The model has been applied to these tests and the comparison has been made, for each test, on the maximum temperature in the air and on the maximum temperature calculated in 2 hypothetical steel sections, one thermally protected and one unprotected. The agreement is very poor for the air and for the unprotected steel temperature, and somewhat better for the protected steel temperature. Some proposals are made which allow to improve the agreement, while keeping the same expressions for the parametric fire. These modifications concern the equivalent thermal properties of multi material walls, and the introduction of a minimum duration of the fire and a of a ventilation effect in case of fuel-bed controlled fires

Steel Hollow Columns filled with self compacting Concrete under Fire Conditions

peer reviewedConcrete filled steel hollow section (CFSHS) columns can carry important loads and therefore are used extensively in the construction of high-rise buildings. Steel hollow sections are filled usually with ordinary concrete, but filling problems may arise with small cross sections and dense reinforcement or hollow sections (tubes) surrounding another profile (tube or H section) when the distance between the two profiles is small. For such a configuration, self-compacting concrete can be recommended. Ten columns filled with self-compacting concrete embedding another steel profile have been tested in the Fire Engineering Laboratory of the University of Liege - Belgium. The non linear finite element software SAFIR developed at the University of Liege has been used to simulate the thermal and structural behavior under fire conditions. A good agreement between numerical and experimental results has been obtained. This shows that SAFIR code can predict well the behavior of CFSHS columns and that the properties of self-compacting concrete at high temperatures can be considered to be the same as those of ordinary concrete. Another purpose of this study was to give practical tools to consulting engineers

Analysis of the fire behaviour of structures. Tests or simulations

Pour quels types de matériaux peut-on faire des simulations? Quels tests dois-je envisager pour mes structures et où? Quelles sont les données d’entrées nécessaires pour faire de la simulation? Quels types d’essais sont possibles pour valider les simulations

Behaviour of single sided composite joints at room temperature and in case of fire after an earthquake

peer reviewedIn 2003, a European research program entitled “PRECIOUS - Prefabricated composite beam-to-concrete filled tube or partially reinforced-concrete-encased column connections for severe seismic and fire loadings” and funded by the Research Fund for Coal and Steel (RFCS) was initiated for three years (Bursi et al, 2008). The objective of this project was to develop fundamental data, design guidelines and prequalification tools for two types of composite beam-to-column joints able to ensure a suitable behaviour during an earthquake and its eventual subsequent fire. At the University of Liege, as part of this project, analytical and numerical investigations were conducted mainly on single-sided beam-to-column composite joints at room and at elevated temperatures. The present paper summarizes the activities developed within this project and presents the main achievements

Numerical modelling of two-way reinforced concrete slabs in fire

This paper describes numerical modelling of the fire behaviour of two-way reinforced concrete slabs using a special purpose non-linear finite-element program, SAFIR. Several two-way reinforced concrete and composite steel-concrete slabs are tested under exposure to the ISO standard fire in order to validate the shell finite element in the SAFIR program. The modelling results showed agreement with the fire tests and demonstrate that the SAFIR shell element can be used to predict tensile membrane behaviour of two-way reinforced concrete slabs in fire conditions. The analyses show that two-way slabs have excellent fire resistance if they deform in double curvature and develop tensile membrane action. (C) 2004 Elsevier Ltd. All rights reserved

Stabilité des Constructions

audience: studen