References of "Gernay, Thomas"
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See detailUrban infrastructure resilience to fire disaster: An overview
Gernay, Thomas ULg; Selamet, Serdar; Tondini, Nicola et al

in Procedia Engineering (in press)

Fire disasters are a serious threat to the functionality of the built environment, in particular in densely populated urban areas where city infrastructure systems are under strain. Yet, fire safety ... [more ▼]

Fire disasters are a serious threat to the functionality of the built environment, in particular in densely populated urban areas where city infrastructure systems are under strain. Yet, fire safety issues are still mostly considered at the level of individual elements or buildings, disregarding the global risk for systems’ functionality. In line with the current efforts toward ensuring more resilient cities, this paper presents an overview of urban infrastructure resilience to fire disaster. The definitions of resilience and the quantitative frameworks established for other hazards such as earthquakes are reviewed. Then, the specificities of structural fire engineering are presented and it is shown how resilience frameworks could be applied to fire hazard. Finally, the paper identifies areas where further research efforts are needed. [less ▲]

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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 detailCritical parameters in deriving fire fragility functions for steel gravity frames
Gernay, Thomas ULg; Elhami Khorasani, Negar; Garlock, Maria

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

Fire fragility functions can be used to characterize the probabilistic vulnerability of buildings to fire in the context of urban resilience assessment. A methodology has been proposed to develop such ... [more ▼]

Fire fragility functions can be used to characterize the probabilistic vulnerability of buildings to fire in the context of urban resilience assessment. A methodology has been proposed to develop such functions for multi-story steel buildings. However, a large number of parameters with uncertainties play a role in the process of constructing the fragility functions. The goal of this research is to identify the critical parameters that most affect the global fire safety by investigating the sensitivity of the fragility functions to different input parameters. Sensitivity in parameters affecting the fire model, the heat transfer process and the thermo-mechanical response is examined. The effects of different design assumptions at the system level are also studied. The presented approach is useful for selecting the prevailing parameters in a fire reliability analysis and it provides important information for modeling tools that can be used to evaluate resilience for fire scenarios. [less ▲]

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See detailConversion of visual post fire measurements into fire severity with the aid of thermo-plastic analysis for retrofitting
Molkens, Tom; Gernay, Thomas ULg; Van Coile, Ruben

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

At Koksijde in Belgium a severe fire took place in an apartment building in 2015, resulting in the death of a young man and visible structural damage to four balconies. Following the fire, experts were ... [more ▼]

At Koksijde in Belgium a severe fire took place in an apartment building in 2015, resulting in the death of a young man and visible structural damage to four balconies. Following the fire, experts were mandated to assess the damage and the need for structural repair. They estimated that the balconies had to be refurbished but that there were no other structural elements affected, in particular the slab inside the apartment could be left in place with only a surface treatment and new plaster finishing. However, the floor slab in the apartment located above the fire apartment exhibited several visual indications that the fire could have had a structural impact, such as residual deformations and cracks in the tiles. This paper presents a methodology to infer the fire severity based on post-fire measurements and non-linear thermo-plastic numerical simulations. Finally, knowing the fire severity, its effect on the structure is evaluated and a reliability-based assessment is made of the residual load bearing capacity of the slab. [less ▲]

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See detailFire fragility functions for community resilience assessment
Elhami Khorasani, Negar; Gernay, Thomas ULg; Garlock, Maria

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

This work provides a framework to evaluate the response of buildings in a community to fire following earthquake. As part of the framework, the paper discusses two methodologies: (1) how to develop fire ... [more ▼]

This work provides a framework to evaluate the response of buildings in a community to fire following earthquake. As part of the framework, the paper discusses two methodologies: (1) how to develop fire fragility functions; (2) how the fire fragility functions can be used in conjunction with an original fire ignition model to estimate the potential losses in a community from fire following earthquake. The paper focuses in particular on the development of fire fragility functions for an entire building to measure the probability of reaching a damage state given a fire scenario. Next, the paper proposes an ignition model to evaluate the probability of fire ignition after an earthquake. The ignition model together with fragility functions measure the probability of damage from fire following earthquake given an earthquake scenario. [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 detailFire Resistance of Reinforced Concrete Columns Subjected to Standard Fire – Comparison of an Advanced and a Simplified Method
Achenbach, Marcus; Gernay, Thomas ULg; Morgenthal, Guido

in Garlock, Maria; Kodur, Venkatesh (Eds.) Structures in Fire (Proceedings of the Ninth International Conference) (2016, June 08)

For designing concrete columns subjected to a standard fire exposure, the Eurocode permits the use of simplified or advanced calculation methods. For the designer, the question of the respective ... [more ▼]

For designing concrete columns subjected to a standard fire exposure, the Eurocode permits the use of simplified or advanced calculation methods. For the designer, the question of the respective advantages of these two types of methods arises. Which situations demand the use of an advanced method? When does a simple method provide sufficient accuracy? In this paper, laboratory tests are recalculated using Finite Element Modeling (FEM) as an advanced and Extended Zone Model (EZM) as a simple method in order to investigate these questions. The recalculations indicate that the simple EZM is of sufficient accuracy for symmetric heated columns without restraints. In contrast, the mechanical behavior of columns heated on three sides demands an advanced method such as FEM to be properly described. [less ▲]

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See detailComportement des structures soumises au feu
Gernay, Thomas ULg

Learning material (2016)

Les incendies représentent une sollicitation importante pouvant agir sur les bâtiments et autres structures du génie civil. Ce cours vise à donner un aperçu de la problématique du feu vis-à-vis des ... [more ▼]

Les incendies représentent une sollicitation importante pouvant agir sur les bâtiments et autres structures du génie civil. Ce cours vise à donner un aperçu de la problématique du feu vis-à-vis des structures et de la manière dont on peut concevoir ces dernières afin qu’elles assurent la sécurité des biens et des personnes en cas d’incendie. Les thèmes abordés couvriront la description des actions thermiques liées au développement d’un incendie et le comportement thermique et mécanique des matériaux à haute température. Les différents moyens de conception anti feu seront présentés ainsi que les méthodes de calcul pouvant mener à un dimensionnement viable face à cette sollicitation exceptionnelle. Finalement, le cours présentera des développements récents en ingénierie de la sécurité incendie et leur implémentation dans des projets réels de grande envergure. [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 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 detailFire Fragility Curves for Steel Buildings in a Community Context: A Methodology
Gernay, Thomas ULg; Elhami Khorasani, Negar; Garlock, Maria

in Engineering Structures (2016), 113

This paper proposes a novel methodology for developing fire fragility functions for an entire steel building - meaning that the function is not specific to a location within the building. The aim is to ... [more ▼]

This paper proposes a novel methodology for developing fire fragility functions for an entire steel building - meaning that the function is not specific to a location within the building. The aim is to characterize the probabilistic vulnerability of steel buildings to fire in the context of community resilience assessment. In developing the fragility functions, uncertainties in the fire model, the heat transfer model and the thermo-mechanical response are considered. In addition several fire scenarios at different locations in the building are studied. Monte Carlo Simulations and Latin Hypercube Sampling are used to generate the probability distributions of demand placed on the members and structural capacity relative to selected damage thresholds. By assessing demand and capacity in the temperature domain, the thermal and the structural problems can be treated separately to improve the efficiency of the probabilistic analysis. After the probability distributions are obtained for demand and capacity, the fragility functions can be obtained by convolution of the distributions. Finally, event tree analysis is used to combine the functions associated with fire scenarios in different building locations. The developed fire fragility functions yield the probability of exceedance of predefined damage states as a function of the fire load in the building. The methodology is illustrated on an example consisting in a prototype nine-story steel building based on the SAC project. [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 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 detailMaintenance, restauration et protection des constructions: réparations structurales des constructions
Gernay, Thomas ULg

Learning material (2015)

Le document est le support PowerPoint du cours donné le 1er décembre 2015 aux étudiants ingénieurs civils des constructions et ingénieurs architectes de l'ULg. Le cours traite du problème de la réparation ... [more ▼]

Le document est le support PowerPoint du cours donné le 1er décembre 2015 aux étudiants ingénieurs civils des constructions et ingénieurs architectes de l'ULg. Le cours traite du problème de la réparation et du renforcement structural des constructions en béton et en acier (ponts, bâtiments). [less ▲]

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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 detailEvaluating a city’s vulnerability to fire following earthquake
Gernay, Thomas ULg

Scientific conference (2015, October 23)

Recent extreme events such as major earthquakes have emphasized the need for disaster-resilient communities. In a resilience framework, the built environment is designed to respond adequately to low ... [more ▼]

Recent extreme events such as major earthquakes have emphasized the need for disaster-resilient communities. In a resilience framework, the built environment is designed to respond adequately to low probability-high consequence events. The latter include cascading multi-hazard events such as fires following an earthquake, which can cause major social and economic losses in a community as observed for instance in the 1989 Loma Prieta and 1994 Northridge events in the United States. This presentation provides a methodology to evaluate the response of buildings in a community subject to fire following earthquake. First, a model is developed to determine the probability of ignition in buildings of a community due to an earthquake. Second, fragility functions are developed for buildings subject to fire, to quantify the structural damage and the expected losses. In the future, the ignition model, combined with the fragility functions, can be implemented in a GIS based risk management platform to evaluate economical losses in a region from fire following an earthquake. [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 detailSensitivity of structures to fire decay phases: quantitative comparison of structural components made of different materials
Gernay, Thomas ULg

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)

This work presents an analysis of the behaviour of different structural members under natural fires, with the aim to characterize their sensitivity to the fire decay phase. Thermo-mechanical numerical ... [more ▼]

This work presents an analysis of the behaviour of different structural members under natural fires, with the aim to characterize their sensitivity to the fire decay phase. Thermo-mechanical numerical simulations based on the non-linear finite element method are conducted using the parametric fire model of Eurocode to represent the natural fires. Results show that, for all the studied members (column, beam) and materials (reinforced concrete, steel, timber), structural failure during or after the cooling phase of a fire is a possible event. The major factors that promote delayed structural failure are the thermal inertia and the constituting material of the member. An indicator is proposed to quantify the propensity to delayed failure for structural members under natural fire. This work enhances the understanding of the structural behaviour under natural fires and has implications for the safety of the fire brigades and people proceeding to a building inspection after a fire. [less ▲]

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