References of "Gernay, Thomas"
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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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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 detailTools for Measuring a City’s Resilience in a Fire Following Earthquake Scenario
Elhami Khorasani, Negar; Gernay, Thomas ULg; Garlock, Maria

in Proceedings of IABSE Conference - Structural Engineering: Providing Solutions to Global Challenges (2015, September 25)

The paper provides a framework 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 ... [more ▼]

The paper provides a framework 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. 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 detailFragility Analysis of a Steel Building in Fire
Gernay, Thomas ULg; Elhami Khorasani, Negar; Garlock, Maria

in Usmani, Asif; Lu, Yong; Das, Purnendu (Eds.) Proceedings of the First International Conference on Structural Safety under Fire & Blast - CONFAB 2015 (2015, September 03)

Community resilience to extreme events is an issue of increasing concern in our interconnected and urbanized societies. This work provides a framework to evaluate the response of a community of buildings ... [more ▼]

Community resilience to extreme events is an issue of increasing concern in our interconnected and urbanized societies. This work provides a framework to evaluate the response of a community of buildings to fire following earthquake, a potentially highly destructive cascading multi-hazard event. In a previous part of the work, a model has been developed to predict the probability of ignition in a building due to an earthquake. Given an ignition in a building, the probability of the structure exceeding certain limit states must be evaluated in order to quantify the expected damage loss. Adopting an approach similar to that used in seismic engineering, fragility functions can be developed for structures subjected to fire. The methodology is described here for a prototype nine-story steel frame building. 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. The demand on and capacity of the system are assessed probabilistically in terms of critical temperature. The developed fire fragility functions yield the probability of exceedance of predefined damage states as a function of the fire load in the building. Future works will aim to implement fire fragility functions into a GIS based risk assessment software platform for assessment of the expected risk and cost associated with fire following earthquake for a community of buildings. [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 detailResiliency of a Community of Buildings to Fire Following Earthquake
Gernay, Thomas ULg; Elhami Khorasani, Negar; Garlock, Maria

Conference (2015, June 19)

Cascading multi-hazard events, such as fires following an earthquake, can trigger progressive collapse of structures. In cascading earthquake and fire events, buildings that may have already experienced ... [more ▼]

Cascading multi-hazard events, such as fires following an earthquake, can trigger progressive collapse of structures. In cascading earthquake and fire events, buildings that may have already experienced damage due to a primary earthquake hazard, should cope with a secondary extreme event. This work provides a methodology to evaluate the risk of fire ignitions after an earthquake and building responses in a community. The work has two components: In the first part, a model is developed for predicting the probability of ignition in a building due to an earthquake. This probabilistic model relies on the data from seven significant earthquakes that took place in the U.S. between 1983 and 2014. The main parameters influencing the probability of ignition are found to be the peak ground acceleration, the type of building material, and the main features of the environment in which the buildings are located (i.e. the total square footage and the population density). In the second part of this work, fragility curves are developed for performance of structures under fire, to quantify the probability of exceeding a damage state given a fire scenario. The probabilistic ignition model is implemented in Ergo/Maeviz, a GIS based risk assessment software platform developed at the Mid-America Earthquake Center at UIUC. Ergo/Maeviz provides the probability of ignition after an earthquake for each building in a region of study, and the overall risk for the community. The developed package in Ergo/Maeviz is validated against number of historical fire following earthquake events. For the future work, the developed fragility curves for buildings under fire will be implemented in Ergo/Maeviz to integrate the probability of ignition and possible damage states of the buildings. This research integrates multi-hazard analysis and risk management to plan mitigation and recovery strategies, and to obtain resilient communities. [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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See detailBuilding Structures in Fire: Insights from Numerical Models
Gernay, Thomas ULg

Scientific conference (2015, March 06)

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See detailA plastic-damage model for concrete in fire: Applications in structural fire engineering
Gernay, Thomas ULg; Franssen, Jean-Marc ULg

in Fire Safety Journal (2015), 71

The research aims at developing a new multiaxial constitutive model for concrete in the fire situation. In addition to validity at the material level, a crucial feature of a constitutive model is the ... [more ▼]

The research aims at developing a new multiaxial constitutive model for concrete in the fire situation. In addition to validity at the material level, a crucial feature of a constitutive model is the applicability at the structural level; yet for concrete in fire there remains a serious lack of models combining reliability and robustness. The theoretical aspects and validation of the new model, which rely on a plastic-damage formulation, have been the subject of a former publication; they are briefly summarized here. This paper explores the capabilities of the concrete model for being used in a performance-based structural fire engineering framework. Several examples of numerical simulations by non-linear finite element method are discussed, with emphasis on practical applications that are demanding for the material model. In particular, it is shown that the simulations using the new concrete model succeed in capturing, at ambient temperature, the crack pattern in a plain concrete specimen and the influence of the loading path on reinforced concrete (RC) slabs. At high temperature, the presented applications include a RC slab subjected to furnace fire and a large-scale composite steel–concrete structure subjected to natural fire. In the numerical analyses, no parameter calibration was required on the particular concrete type, except for the uniaxial strengths and tensile crack energy which are to be defined case-by-case. The results illustrate the reliability and numerical robustness of the model. Also, they suggest that satisfactory prediction of structural behavior in fire can be obtained when no additional data is available on the specific properties of the particular concrete mix that is used in the project, as is often the case in practice, by using standard values of parameters. [less ▲]

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See detailSimulation of 5 fire tests on reinforced concrete columns using SAFIR
Gernay, Thomas ULg; Franssen, Jean-Marc ULg

Report (2015)

This report presents the results of numerical simulations on five tests conducted on reinforced concrete columns in fire. The data for the studied RC columns have been provided by the CERIB in the ... [more ▼]

This report presents the results of numerical simulations on five tests conducted on reinforced concrete columns in fire. The data for the studied RC columns have been provided by the CERIB in the document “CEN-TC250-SC2-WG1-TG5_N0043_Annex_C_examples_Jesper_Jensen”. This study is part of the research project CEN-TC250-SC2-WG1-TG5 on the revision of EN1992-1-2, which focuses on the columns. The numerical software that is used for the simulations is the non-linear finite element software SAFIR, version 2013a0. [less ▲]

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See detailA model for concrete in the fire situation and its application in structural fire engineering
Gernay, Thomas ULg

Scientific conference (2014, October 21)

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See detailRevision of the tabulated methods of EN1992-1-2 for concrete columns in fire - Part 2
Gernay, Thomas ULg; Franssen, Jean-Marc ULg

Report (2014)

This report presents the results of numerical simulations conducted on reinforced concrete columns in fire for comparison of the computed fire resistance with the fire resistance obtained by the tabulated ... [more ▼]

This report presents the results of numerical simulations conducted on reinforced concrete columns in fire for comparison of the computed fire resistance with the fire resistance obtained by the tabulated methods of EN1992-1-2. The data for the studied RC columns have been provided by the CERIB in the document “CENTC250-SC2-WG1-TG5_N0038_Column_Calculation”. This study is part of the research project CEN-TC250-SC2-WG1-TG5. The objective is to assess the validity of and possibly to revise the tabulated methods of EN1992-1-2. The numerical software that is used for the simulations is the non-linear finite element software SAFIR, version 2013a0. [less ▲]

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See detailRevision of the tabulated methods of EN1992-1-2 for concrete columns in fire - Part 1
Gernay, Thomas ULg; Franssen, Jean-Marc ULg

Report (2014)

This report presents the results of numerical simulations conducted on reinforced concrete columns in fire for comparison of the computed fire resistance with the fire resistance obtained by the tabulated ... [more ▼]

This report presents the results of numerical simulations conducted on reinforced concrete columns in fire for comparison of the computed fire resistance with the fire resistance obtained by the tabulated methods of EN1992-1-2. The data for the studied RC columns have been provided by the CERIB in the document “CENTC250-SC2-WG1-TG5_N0037_Annex_C_studies_Jesper_Jensen”. This study is part of the research project CEN-TC250-SC2-WG1-TG5. The objective is to assess the validity of and possibly to revise the tabulated methods of EN1992-1-2. The numerical software that is used for the simulations is the non-linear finite element software SAFIR, version 2013a0. [less ▲]

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See detailExperimental tests and numerical modelling on eight slender steel columns under increasing temperatures
Franssen, Jean-Marc ULg; Zhao, Bin; Gernay, Thomas ULg

in Li, G.Q.; Jiang, S.C.; Chen, Suwen (Eds.) et al Progress on Safety of Structures in Fire (2014, June 11)

In order to fill the lack of knowledge about slender elements behavior at elevated temperatures, a European research project called FIDESC4 has been funded by the RFCS. This project involves experimental ... [more ▼]

In order to fill the lack of knowledge about slender elements behavior at elevated temperatures, a European research project called FIDESC4 has been funded by the RFCS. This project involves experimental testing, parametric numerical analyses and development of simple design rules. The present paper reports the characteristics and the results of the FIDESC4 experimental test campaign performed at the University of Liege on slender steel columns at elevated temperatures. A total of eight columns have been tested, all of them with I shape section. Six columns were made of welded sections (some prismatic and some tapered members) and two columns were with hot rolled sections. The nominal length of the columns was 3 meters with the whole length being heated. The strength of the material (webs and flanges) was measured on sample before the tests. The order of magnitude of the initial geometrical imperfections was recorded. The columns were not restrained against longitudinal thermal elongation. The supports at the ends were cylindrical thus inducing a restrain against rotation in one plane while allowing rotation in the other plane. The allowed direction of rotation was chosen in each test to induce buckling around the strong or the weak axis. The load was applied at ambient temperature and maintained for a period of 15 minutes after which the temperature was increased under constant load. The load was applied concentrically on some tests and with an eccentricity in other tests. The load eccentricity was either applied at both ends, leading to constant bending moment distribution along the length, or at one end only, leading to a triangular bending moment distribution. Heating was applied by electrical resistances enclosed in ceramic pads. The columns and the ceramic pads were wrapped in ceramic wool insulating material. This technique was preferred to gas heating in a standard test furnace because it allows applying a slower and better controlled heating rate and thus obtaining a more uniform temperature distribution in the member. It is also easier to measured lateral displacements of the column. Preliminary blank tests were performed on unloaded specimen in order to determine the heating range to be used later on the loaded columns. The paper will also report on a modification of the heating technique that was applied and improved significantly the uniformity in the temperature distribution. Numerical simulations were performed before the tests using shell elements of the software SAFIR and assumed values of the material properties in order to predict the failure modes. It was essentially crucial to determine whether lateral supports at intermediate levels should be provided in order to ensure failure in the desired direction. Experience showed that the failure modes developed as predicted by the numerical simulations. Besides a thorough description of the experiments, the paper will also present the obtained results in terms of failure mode, ultimate temperature and evolution of longitudinal and transverse displacement. Some information will also be given about the level of detail that has to be used in the numerical model in order to get accurate results at a reasonable price. [less ▲]

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See detailL'étude du béton dans le cadre de la sécurité incendie
Gernay, Thomas ULg

Scientific conference (2014, March 14)

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