References of "Franssen, Jean-Marc"
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See detailLoadbearing capacity criteria in fire resistance testing
Dumont, Fabien ULg; Wellens, Eric ULg; Gernay, Thomas ULg et al

in Materials and Structures (2016), 49(11), 4565-4581

The European system for fire testing and classification of loadbearing building elements lacks consistency because the two standards that have to be applied prescribe different criteria for assessing the ... [more ▼]

The European system for fire testing and classification of loadbearing building elements lacks consistency because the two standards that have to be applied prescribe different criteria for assessing the loadbearing performance. This article analyzes the implications of the present conflict between the standard for testing and the standard for classification. The prescribed criteria for loadbearing performance are related to the exceedance of deflection and rate of deflection thresholds. A database of 46 fire resistance tests performed at the University of Liege is collected that contains the time at which these thresholds are reached in fire tests with different typologies of elements (walls, floors, columns and beams). Then, the loadbearing performance (and hence the fire resistance rating) can be derived according to the two standards. The evolutions of deflection and rate of deflection during the tests are also analyzed to gain a better understanding of the adequacy of the standards. The selection of one or the other standard affects the time at which “failure” is deemed to occur in fire tests. Statistically speaking, the difference in terms of failure time that results from using one or the other standard has a 25% probability to exceed 10%. In certain cases, this results in a difference in fire resistance rating; this was observed for 3 of the analyzed tests. The apparent contradiction in two codes in application has potential practical implications and therefore needs to be solved. The article suggests some guidelines for defining homogenized and consistent criteria. [less ▲]

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See detailA Novel Methodology for Hybrid Fire Testing
Sauca, Ana ULg; Gernay, Thomas ULg; Robert, Fabienne et al

in Proceedings of the 6th European Conference on Structural Control (2016, July 11)

This paper describes a novel methodology for conducting stable hybrid fire testing (HTF). During hybrid fire testing, only a part of the structure is tested in a furnace while the reminded structure is ... [more ▼]

This paper describes a novel methodology for conducting stable hybrid fire testing (HTF). During hybrid fire testing, only a part of the structure is tested in a furnace while the reminded structure is calculated separately, here by means of a predetermined matrix. Equilibrium and compatibility at the interface between the tested “physical substructure” and the “numerical substructure” is maintained throughout the test using a dedicated algorithm. The procedures developed so far are sensitive to the stiffness ratio between the physical and the numerical substructure and therefore they can be applied only in some cases. In fire field, the stiffness of the heated physical substructure may change dramatically and the resulting change in stiffness ratio can lead to instability during the test. To overcome this drawback, a methodology independent of the stiffness ratio has been developed, inspired from the Finite Element Tearing and Interconnecting (FETI) method, which has been originally developed for substructuring in numerical analyses. The novel methodology has been successfully applied to a hybrid fire test in a purely numerical environment, i.e. the physical substructure was also modelled numerically. It is shown that stability does not depend on the stiffness ratio and that equilibrium and compatibility can be consistently maintained at the interface during the fire. Finally, the ongoing experimental program aimed at employing and experimentally validating this methodology is described. [less ▲]

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See detailTowards a standard measure of the ability of a structure to resist a natural fire
Gernay, Thomas ULg; Franssen, Jean-Marc ULg

in Garlock, Maria; Kodur, Venkatesh (Eds.) Structures in Fire (Proceedings of the Ninth International Conference) (2016, June 10)

Fire brigades face a major threat when intervening in a building in fire: the possibility of structural collapse during the cooling phase of the fire, or soon thereafter. In the current approaches to ... [more ▼]

Fire brigades face a major threat when intervening in a building in fire: the possibility of structural collapse during the cooling phase of the fire, or soon thereafter. In the current approaches to structural fire engineering, the fire resistance rating (R) is generally the only measure taken into consideration to characterize the fire performance of structural elements, although this measure does not reflect the response in real fire conditions. In this work, a standard measure is proposed to characterize the ability of structural members to resist a natural fire including the decay phases. This measure yields information about the potential occurrence of delayed failure as a function of the duration of the fire before it started to decrease, whether by self-extinction or due to the action of the fire fighters. The paper presents the method to derive this new standard measure as well as results for different typologies of structural elements. Finally, the interpretation and practical consequences are discussed, in particular regarding the safety of fire fighters during an intervention. [less ▲]

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See detailStability in Hybrid Fire Testing
Sauca, Ana ULg; Gernay, Thomas ULg; Robert, Fabienne et al

in Garlock, Maria; Kodur, Venkatesh (Eds.) Structures in Fire (Proceedings of the Ninth International Conference) (2016, June 09)

Hybrid testing is an appealing technique to observe the behavior of an element in an experimental test while taking into account the interaction with the rest of the structure which is modelled ... [more ▼]

Hybrid testing is an appealing technique to observe the behavior of an element in an experimental test while taking into account the interaction with the rest of the structure which is modelled numerically. Being widely used in the seismic field, this technique has been recently proposed in the fire field. The purpose of this paper is to demonstrate that the loading control process may be unstable during the hybrid testing when using the methodology applied in former tests presented in the literature. The stability in the latter method depends on the stiffness ratio between the two substructures. For the purpose of discussion, a one degree-of-freedom elastic system is studied. To overcome the stability issues, a new method is presented, independent on the stiffness ratio. Finally, the hybrid testing of a 2D beam being part of a moment resisting frame is analyzed in a virtual environment (both parts being modeled numerically) using the “first generation method” and the new proposed method. [less ▲]

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See detailSteel hollow columns with an internal profile filled with self-compacting concrete under fire conditions
Chu, Thi Binh; Gernay, Thomas ULg; Dotreppe, Jean-Claude ULg et al

in Proceeding of the Romanian Academy. Series A, Mathematics, Physics, Technical Sciences, Information Science (2016), 17(2), 152-159

A detailed experimental and numerical investigation has been performed on the behavior under fire conditions of concrete filled steel hollow section (CFSHS) columns. In this study the internal ... [more ▼]

A detailed experimental and numerical investigation has been performed on the behavior under fire conditions of concrete filled steel hollow section (CFSHS) columns. In this study the internal reinforcement consists of another profile (tube or H section) being embedded with the concrete, and filling is realized by self-compacting concrete (SCC). Ten columns filled with self-compacting concrete embedding another steel profile have been tested in the Fire Testing Laboratory of the University of Liege, Belgium. Numerical simulations on the thermal and structural behavior of these elements have been made using the non linear finite element software SAFIR developed at the University of Liege. There is a rather good agreement between numerical and experimental results, which can be slightly improved by using the ETC (Explicit Transient Creep) model incorporated in SAFIR. This shows that numerical analyses can predict well the behavior of CFSHS columns under fire conditions. The properties at high temperatures of self-compacting concrete are considered the same as those of ordinary concrete. [less ▲]

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See detailExperimental Tests and Numerical Modelling on Slender Steel Columns at High Temperatures
Franssen, Jean-Marc ULg; Zhao, Bin; Gernay, Thomas ULg

in Journal of Structural Fire Engineering (2016), 7(1), 30-40

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 ... [more ▼]

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. [less ▲]

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See detailTemperature assessment of a vertical steel member subjected to localised fire
Dumont, Fabien ULg; Wellens, Eric ULg; Franssen, Jean-Marc ULg

Textual, factual or bibliographical database (2016)

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See detailFire safety engineering group: presentation of the research activities at the ULg PhD information session
Franssen, Jean-Marc ULg; Gernay, Thomas ULg

Diverse speeche and writing (2015)

Presentation of the research activities of the fire safety engineering group headed by Jean-Marc Franssen at University of Liege

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See detailNew features in SAFIR® 2016
Franssen, Jean-Marc ULg; Gernay, Thomas ULg

Scientific conference (2015, November 05)

This presentation gives an overview of the new features implemented in the version 2016 of SAFIR, the finite element software dedicated to the analysis of buildings in fire.

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See detailEssentials of actions
Cerfontaine, Benjamin ULg; Collin, Frédéric ULg; Denoël, Vincent ULg et al

Learning material (2015)

This document deals with the philosophy of safety in civil engineering structures, including loads and load combinations to be applied when designing a structure. It contains general concepts that are ... [more ▼]

This document deals with the philosophy of safety in civil engineering structures, including loads and load combinations to be applied when designing a structure. It contains general concepts that are presented and discussed as well as values for some important input data that can be used as order of magnitude in the initial phase of a project. [less ▲]

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See detailFire Design of Steel Structures Second edition : Eurocode 1: Actions on structures. Part 1-2: Actions on structures exposed to fire: Eurocode 3: Design of steel structures: Part 1-2: Structural fire design
Franssen, Jean-Marc ULg; Vila Real, Paulo

Book published by Wiley (2015)

The first edition of Fire Design of Steel Structures was published by ECCS as paperback in 2010. Since 2012, this publication is also available in electronic format as an e-book. Nevertheless, the ... [more ▼]

The first edition of Fire Design of Steel Structures was published by ECCS as paperback in 2010. Since 2012, this publication is also available in electronic format as an e-book. Nevertheless, the interest for this publication was so high that it appeared rapidly that the paper copies would be sold out within a short time and a second edition would have to be printed. The authors took the opportunity of this second edition to review their own manuscript. The standards that are described and commented in this book, namely EN 1991-1-2 and 1993-1-2, are still in application in the same versions as those that prevailed at the time of writing the first edition. It was nevertheless considered that an added value would be given by, first, rephrasing some sentences or sections that had generated questions by some readers but, above all, adding some new material for the benefit of completeness. The new material namely comprises:  A section dealing with the thermal response of steel members under several separate simultaneous localised fires, including one worked example with multiple fire scenarios in a car park (Chapter 4);  An important section on classification of cross-sections. The case of combined bending and axial force, including one worked example comparing different methodologies to obtain the position of the neutral axis, has been added (Chapter 5);  A worked example of a beam-column with Class 4 cross-section (Chapter 5);  A new section with comparisons between the simple and the advanced calculation models in Chapter 6 (shadow factor – including one example, buckling curves and adaptation factors κ1 and κ2);  New references have been included. [less ▲]

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See detailAnalysis of a concrete building exposed to natural fire
Sauca, Ana ULg; Gernay, Thomas ULg; Robert, Fabienne et al

in Wald, F.; Burgess, I.; Jelcic Rukavina, M. (Eds.) et al Proceedings of the Int. Conf. ASFE in Dubrovnik, 15-16 October 2015 (2015, October 16)

In this paper is presented the analysis of a concrete building exposed to OZone fire. The temperature development in the elements and the structural behaviour were calculated in SAFIR using beam elements ... [more ▼]

In this paper is presented the analysis of a concrete building exposed to OZone fire. The temperature development in the elements and the structural behaviour were calculated in SAFIR using beam elements for the columns and beams and shell elements for the floor slabs. The first floor was modelled and the effects of action from the upper storeys are applied as external loads. It is shown how the numerical analysis allows understanding the behaviour of the structure when exposed to a natural fire until complete cooling by analysing the evolution of displacements, the distributions of bending moments in the beams, the membrane forces in the slab, and the stresses in the elements. All this detailed information would not be available from an experimental test. [less ▲]

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See detailThe development of Structural Fire Engineering over the past 25 years and issues for the future
Franssen, Jean-Marc ULg

Conference (2015, October 15)

This talk presents a series of thoughts of the author from his observation of the evolution of structural fire engineering since the beginning of his career Experimental research works are discussed ... [more ▼]

This talk presents a series of thoughts of the author from his observation of the evolution of structural fire engineering since the beginning of his career Experimental research works are discussed, either on the behavior of materials or on the behavior of structures. The rest of the presentation is dedicated to calculation methods: tabulated data, simple calculation models and general calculation models. For numerical calculation models, the presentation contains a brief history of appearance of different software, of their objectives, of their capabilities… Some examples are presented of structures recently modelled in real applications. Possible abusive utilizations of numerical modelling are also shown. The presentation ends with a presentation of some challenges that the discipline is facing for the future. [less ▲]

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See detailA performance indicator for structures under natural fire
Gernay, Thomas ULg; Franssen, Jean-Marc ULg

in Engineering Structures (2015), 100

Fires in buildings are characterized by a heating phase followed by a cooling phase, yet the effects of the latter on structures are not well covered in the current approaches to structural fire ... [more ▼]

Fires in buildings are characterized by a heating phase followed by a cooling phase, yet the effects of the latter on structures are not well covered in the current approaches to structural fire engineering. Indeed the actual requirement of non-occurrence of structural failure at peak temperature does not guarantee against a delayed failure during or after the cooling phase of a fire, which puts at risk the fire brigades and people proceeding to a building inspection after a fire. Therefore there is an urgent need to better comprehend and characterize the materials and structures behavior under decreasing temperatures. Sensitivity to delayed failure of a structural component depends on its typology and constituting materials. In particular, two structural components with the same Fire Resistance rating (R) under standardized fire may exhibit very distinct behavior under natural fire, one of them being more prone to delayed failure than the other. With the aim of quantifying this effect, a new indicator is proposed that characterizes the performance of structures under natural fire conditions. The paper presents the methodology to derive this new indicator as well as results for different typologies of structural components. Parametric analyses highlight the prime influence of constitutive material and thermal inertia of the element on the post-peak behavior. Used in conjunction with the Fire Resistance rating, it is shown how the new indicator carries additional and significant information for classifying structural systems in terms of their fire performance and propensity to delayed failure. [less ▲]

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See detailSAFIR: Capabilities and examples of applications
Gernay, Thomas ULg; Scifo, Anthony ULg; Franssen, Jean-Marc ULg

Report (2015)

This document presents the capabilities of the software SAFIR, as well as examples of applications. SAFIR is a computer program that models the behavior of building structures subjected to fire. The ... [more ▼]

This document presents the capabilities of the software SAFIR, as well as examples of applications. SAFIR is a computer program that models the behavior of building structures subjected to fire. The structure can be made of a 3D skeleton of linear elements such as beams and columns, in conjunction with planar elements such as slabs and walls. Volumetric elements can be used for analysis of details in the structure such as connections. Different materials such as steel, concrete, timber, aluminum, gypsum or thermally insulating products can be used separately or in combination in the model. [less ▲]

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See detailCharacteristics and implementation of Hybrid Fire Testing (HFT)
Sauca, Ana ULg; Gernay, Thomas ULg; Robert, Fabienne et al

Conference (2015, June 18)

This presentation is dedicated to real time hybrid testing of building members subjected to the action of fire. It will be shown why, whereas pseudo-dynamic testing is possible in other fields, real time ... [more ▼]

This presentation is dedicated to real time hybrid testing of building members subjected to the action of fire. It will be shown why, whereas pseudo-dynamic testing is possible in other fields, real time hybrid testing is the only possible option for the evaluation of fire performance (except, perhaps, for pure metallic unprotected structures). For some structures subjected to fire, the load bearing mechanism in the physical component is completely modified during the test and this modification can take place within a very short period of time. Because of that, the computational demand can be very challenging if the simulated element is simulated in a fully nonlinear computer model, especially if the thermal problem (temperature distribution in the structure) and the mechanical problem have both to be solved within each time step. In order to avoid these difficulties, a possible solution may be to calculate the stiffness matrix that dictates the reaction of the simulated element on the tested element before the test. This matrix can be constant or vary as a function of the displacements measured at the interface during the test. This procedure is very robust but it also has some shortcomings and limitations. The main topic of this paper is the discussion of the advantages and limitations of this procedure applied to hybrid fire testing. A series of three tests which is now under preparation to be performed in the furnace PROMETHEE of CERIB, in France, will also be described in this respect. Preliminary results will be presented if some or all of the tests have been performed at the date of the conference. [less ▲]

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