Olivier Vassart

• Professor
• CEO at ArcelorMittal

In 2020, 37% of global CO2eq. emissions were attributed to the construction sector. The major effort to reduce this share of emissions has been focused on reducing the operational carbon of buildings. Recently, awareness has also been raised on the role of embodied carbon: emissions from materials and construction processes must be urgently address...

The building and construction sector is responsible for approximately 40 % of global carbon emissions, and if improvement is not made in the short term, this impact will probably double in the next 20 years. Recently, the European Green Deal set a target of achieving net‐zero greenhouse gas emissions by 2050, for which the construction industry wil...

In the frame of the European RFCS-TRAFIR project, different natural fire tests in large compartment were conducted by Ulster University, involving steel structure and aiming at understanding the conditions in which a travelling fire develops, how it behaves and impacts the surrounding structure. During the experimental programme, the path and geome...

Purpose In the frame of the European RFCS TRAFIR project, three large compartment fire tests involving steel structure were conducted by Ulster University, aiming at understanding in which conditions a travelling fire develops, as well as how it behaves and impacts the surrounding structure. Design/methodology/approach During the experimental prog...

In the frame of the European RFCS-TRAFIR project, natural fire tests in large compartment were conducted by Ulster University, involving steel structure and aiming at understanding the conditions in which a travelling fire develops, how it behaves and impacts the surrounding structure. During the experimental programme, the path and geometry of the...

In the frame of the European RFCS (Research Fund for Coal and Steel) TRAFIR (Characterization of TRAvelling FIRes in large compartments) project, three natural fire tests in a large compartment were conducted at Ulster University. The aim of this investigation was to understand the conditions in which the travelling fires develop and to study the i...

The term “travelling fire” is used to label fires which burn locally and move across the floor over a period of time in large compartments. Through experimental and numerical campaigns and while observing the tragic travelling fire events, it became clear that such fires imply a transient heating of the surrounding structure. The necessity to bette...

In the frame of the European RFCS TRAFIR project, three large compartment fire tests involving steel structure were conducted by Ulster University, aiming at understanding in which conditions a travelling fire develops, as well as how it behaves and impacts the surrounding structure. During the experimental programme, the path and geometry of the t...

Slim floor systems possess favourable thermal and thermo-mechanical behaviour in comparison with the traditional steel-concrete composite beams. Despite a recent surge in their usage in the construction sector, there is limited research on their performance at elevated temperatures. Due to limited investigations, there is a lack of fire design guid...

Purpose: The purpose of this paper is to propose a simplified representation of the fire load in computational fluid dynamics (CFD) to represent the effect of large-scale travelling fire and to highlight the relevance of such an approach whilst coupling the CFD results with finite element method (FEM) to evaluate related steel temperatures, compari...

The paper presents the development of an innovative cost-effective fire protection system for steel columns, which is quick and easy to install and to dismantle. In terms of assembly, this protection is designed to be a plug-and -play system, which is made of two U-shaped half-protections that encapsulate a column. They are composed of high-density...

Fires in open large-floor plan spaces do not always reach a post-flashover fire state and recently, the “travelling fire” terminology has been used to define fires burning locally and moving across entire floor plates over a period of time [1]. Several studies have been presented about the behavior of a structure when it is subjected to this fire s...

The response of structures exposed to fire is highly dependent on the type of fire that occurs, which is in turn very dependent on the compartment geometry. In a European research project, computational fluid dynamics simulations were carried out to analyse the influence of compartment geometry and the interaction with representative fuel loads to...

This paper presents the extended travelling fire method (ETFM) framework, which considers both energy and mass conservation for the fire design of large compartments. To identify its capabilities and limitations, the framework is demonstrated in representing the travelling fire scenario in the Veselí Travelling Fire Test. The comparison between the...

Purpose This paper aims to describe coupon tests performed at elevated temperatures on S355 to S500 steel grades and comparison of test results with previous research studies and current EN 1993-1-2 material laws. The objective is to state if these steel grades satisfy to the current material laws and if the scope of application of these laws could...

This paper describes an analytical model developed for design purposes with the aim to assess the radiative heat flux to a vertical element subjected to a localised fire. It focuses on the calculation of the radiative heat flux, which represents the main source of heating of vertical members that are not engulfed into the fire. The model exploits t...

n recent times, the use of steel sections with web openings has become common as slim floor beams since they offer a reduction in weight of the steelwork, accommodate services within the floor depth and provide the composite action. The composite action in these beams is achieved either through the concrete dowels or through concrete plugs. Though...

Steel beams with web openings are widely used in constructions to reduce the weight of steelwork, especially in structures comprising of traditional composite beams with down-stand steel sections. In recent times, the use of steel sections with web openings has become common as slim floor beams since they offer a reduction in weight of the steelwor...

Elevated temperatures, above 400oC, starts altering the mechanical properties of steel and may lead to the collapse of a structure. Performance-based approaches allow designers to assess more precisely the elevation of temperature in a structure subjected to a compartment fire or under localised fire. This paper presents a part of a major research...

The response of structures exposed to fire is highly dependent on the type of fire that occurs, which is in turn very dependent on the compartment geometry. In the frame of the European RFCS TRAFIR project, CFD simulations using FDS software were carried out to analyse the influence of compartment geometry and the interaction with representative fu...

Angelina beam is a patented type of beam with large sinusoidal openings. Such a geometry allows to let important section pipes and other HVAC systems through its web. The sinusoidal shape of its openings brings an aesthetic aspect to structures and it requires only one cut in the web which permits an economic fabrication process. Web post buckling...

Two experimental programmes launched on thermo-mechanical steel grades ranging from S355 to S500 in 2011 and 2015 are presented in this paper. Both steady-state (constant temperature, as defined in testing standards) and transient-state (constant mechanical loading, closer to real conditions of structures subjected to fire) testing procedures have...

Post flashover fires are unlikely to occur in open spaces or large buildings where temperature is not uniformly distributed. However localised fire remains a potential threat to the structures exposed to fire in these typologies. This paper discusses experimental tests performed on circular column exposed to localised pool fires and numerical simul...

A new type of cellular beams fabricated from hot rolled profiles appeared recently, whose openings have a sinusoidal shape. These beams are used either for steel or composite structures and they allow rectangular ducts, even with large sizes, to pass through their openings. They can thus lead to a substantial reduction of the floor thickness and th...

Performance-based approaches are more and more widely-used for assessment of open car parks behaviour in case of fire. The Annex C of the current EN 1991-1-2 already includes formulae to evaluate the temperatures in the plume along the vertical flame axis of a localised fire when the flame does not impact the ceiling. It also allows evaluating the...

In recent publications, the results of coupon tests performed on high-strength steel (mainly S460M and S460N) have been presented. Some of these tests led to ratios between the coupon resistances at elevated temperatures and at room temperature lower than the Eurocode reduction factors. The authors of these publications have consequently questioned...

Purpose This paper aims to present 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. Design/methodology/approach Particular emphasis is given to the weak co...

This paper describes the model developed during the European LOCAFI1 project with the aim to assess the temperature of a vertical element subjected to a localised fire in a compartment. This model focuses on the calculation of heat fluxes with a special emphasis on the radiative heat flux which governs the temperature for sections of a vertical mem...

This paper presents two experimental fire tests performed at the University of Liege in the scope of an internal project supported by ArcelorMittal Global R&D and focused on the fire resistance of S460M and S500M steel grades at high temperatures. Two similar beams have respectively been subjected to fast (standard ISO curve) and slow (fixed 5°C/mi...

This paper describes the series of pool fire tests performed by the Universities of Liege and Ulster in order to assess the heat fluxes received by vertical members in case of localised fires. All these tests, performed in the scope of the RFCS project LOCAFI, have allowed gathering a large amount of experimental data for calibration and validation...

This paper summarizes the results of a two-year-long research project conducted by the CTBUH on the life cycle assessment (LCA) of tall building structural systems. The research project was made possible thanks to a $300,000 contribution from ArcelorMittal and the support of some of the most important structural engineering firms and players in the...

Cet article décrit deux tests expérimentaux réalisés à l'Université de Liège dans le cadre d'un projet interne d'ArcelorMittal Global R&D et portant sur l'évolution de la résistance des aciers S460M et S500M à hautes températures. Deux poutres métalliques similaires ont respectivement été soumise à des élévations de température rapide (courbe de fe...

The design of metallic structures is governed by construction standards such as the Eurocodes, developed in the 80s with the aim of harmonizing design and calculation procedures in Europe. As far as industrial halls are concerned, there is a lack of detailed recommendations about the methods to use for the calculation of internal forces. Several de...

This paper illustrates the tasks completed so far and the initial findings of the first part of a 24-month long, 300k$ research project on the Life-Cycle Assessment of tall building structures. The research is aimed at investigating the energy / sustainability differentials of steel, concrete and composite structural systems in tall buildings, when...

This document is a report with worked examples presenting the fire resistance assessment of structures according to the Eurocodes. The authors were involved in the preparation and/or assessment of the Eurocodes structural fire design parts. Each chapter of the report focuses on a specific structural material (i.e. steel, concrete, masonry, etc.) an...

New type of cellular beams with sinusoidal shape of openings shows a specific behavior in comparison with the standard circular openings. Full scale tests were realized on three beams representing various dimensions of the openings. The aim was to observe the failure modes of these beams and to obtain the ultimate values of strength. The specimens...

The paper presents a numerical investigation, done with the computer program SAFIR, in order to obtain simpler finite element models for representing the behaviour of the partially protected composite steel concrete slabs in fire situations, considering the membrane action. Appropriate understanding and modelling of the particular behaviour of comp...

The growing use of cellular beams in steel construction leads to the development of various configurations such as curved and tapered cellular beams. In order to provide a tool predicting the behavior of those beams for design applications, the CTICM developed a software based on analytical formulas with adaptation to the curved and tapered cellula...

This paper presents the results of an experimental campaign performed to assess the effect of the flame emissivity for steel members engulfed into fire. In detail, two sizes of circular steel tubes were engulfed into pool fires of two different diameters. Two fuels were used and for both fuels tests without column (used as comparison with existing...

The “Maison de la Paix” building will be built for the Graduate Institute of International and Development Studies in Geneva (IHEID). At its heart will be a library, numerous auditoriums and seminar rooms and a cafeteria. A complete fire analysis has been performed to optimise the steel structures.

The new steel bridge " Hans-Wilsdorf " in Geneva is an exceptional steel structure that will drive general traffic through a main transportation axis. As the investment cost of the project is important, a structural fire analysis has been performed to study the sensitivity of the structure to a high temperature exposure, such as a truck in fire on...

Present paper deals with the behavior of so-called cellular members against lateral torsional buckling. These beams comprising regularly-spaced web openings are especially used for their high resistance-weight ratio, the possibility to integrate service pipes within their height, and aesthetics. Such profiles usually exhibit a complex behavior, sin...

This paper describes a full-scale fire test performed recently on a composite floor for analysing the possibility for tensile membrane action to develop when unprotected steel beams in the central part of the floor are made of cellular beams. The natural fire was created by a wood crib fire load of 700 MJ/m 2 and the 9 m 3 15 m floor survived the f...

As part of an international major research initiative, dealing with the behaviour of long span cellular beams in steel framed buildings under fire, a large-scale fire test incorporating 15m long cellular beams was carried out. The test incorporated unprotected secondary cellular steel beams acting compositely with the supporting floor slab. The flo...

This paper describes a full-scale fire test performed recently on a composite floor for analysing the possibility for tensile membrane action to develop when unprotected steel beams in the central part of the floor are made of cellular beams. The natural fire was created by a wood crib fire load of 700 MJ/m(2) and the 9 m 3 15 m floor survived the...

This thesis has developed an analytical model for the prediction of the critical temperature of cellular beam made based rolled in fire situation. These results will be based on the development of a new analytical model of isostatic cellular beam subjected to fire. To ensure the reliability of the developed model, the following steps were considere...

This paper treats questions on sustainability concerning environmental issues that have implements on the use of steel in the construction sector. The impact of construction on sustainability issues is investigated. The overall objective of this paper is to outline the opportunities for steel in the construction industry with respect to environment...

With the development of the membrane action concept over UK market, Steel Alliance, with a sponsoring from both ArcelorMittal and CTICM, launched the project FRACOF of which the main objective is to extend above design method to other European national markets, especially under ISO fire condition with the purpose of getting the maximum benefit from...

A lot of research projects have been undertaken by ArcelorMittal, in the area of ‘Cellular Beam Design’.  ese have led to the creation of new design methods and userfriendly design software. Not long ago, the famous Paris-based architect Mr Claude Vasconi requested ArcelorMittal for assistance in designing a more architectural and ‘sensual’ cellul...

Research Fund for Coal and Steel (RFCS) Contract No RFS2-CT-2005-00037, 1 July 2005 to 31 December 2006 The results of the ECSC project LARGE WEB OPENINGS FOR SERVICE INTEGRATION IN COMPOSITE FLOORS have been summarised and made available to practitioners via the following documents: — Report on "State of the art and special cases of the design of...

This paper describes an experimental and numerical study at both ambient and elevated temperatures on the behaviour of full-scale composite floor cellular steel beams. A total of four specimens, comprising two different steel geometries and loading conditions were tested under monotonic loading and at elevated temperatures. All beams were designed...

In view of recent disasters and their immense economical and human consequences such as the flood catastrophe in South East Asia or the constant threat by international terrorism more and more focus is given not only on the safety of structures - to reduce the risk for the life of people by collapse even under exceptional loading - but on minimisin...

This work deals with the fire safety engineering analysis of a construction project located in the city of Esch/Alzette, Luxembourg. The studied structure is a hall made of portal frames comprising steel columns and cambered cellular beams. The frames are interconnected by means of steel purlins and a bracing system. In a first step, the entire str...

For simple storey buildings, the structural behaviour in case of fire is relevant only for the safety of the firemen. The protection of occupants and goods is a matter of fire spread, smoke propagation, active fire fighting measures and evacuation facilities. Brittle failure, progressive collapse and partial failure of façades elements outwards may...

The broad technical objective of this proposal is to disseminate effectively Structural Fire Safety Engineering Knowledge, gained in numerous ECSC funded projects during the last 25 years, into practical use. The aim is to this as widely as possible, in various countries and in the various national languages. The first part of this work is covered...

The fire performance of composite steel framed buildings with composite floors (concrete slab connected to steel beams by means of headed studs) is shown, through large-scale fire tests conducted in a number of countries and observations of actual building fires, to be much better than indicated by standard fire resistance tests on isolated structu...

The growing popularity of the use of Cellular steel beams in composite floors comes at the same time as an increasing attention to the fire safety engineering design. The recommendation for their design in fire limit states remains very primitive and this is due to the lack of general research in this area. Six composite cellular steel beams were t...