Applications of Structural Fire Engineering

PREFACE

Ian W. Burgess — 2016-01-18

Preface to Proceedings of the International Conference in Dubrovnik, 15-16 October, 2015.

Keynote lecture: DEVELOPMENT OF STRUCTURAL FIRE ENGINEERING OVER THE PAST 25 YEARS AND ISSUES FOR THE FUTURE

Jean-Marc Franssen — 2016-01-18

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 first discussed, on the behaviour of materials as well as on the behaviour 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.

Keynote lecture: THE PAST AND FUTURE OF STRUCTURAL FIRE ENGINEERING IN THE USA

John L. Gross — 2016-01-18

This Keynote Lecture recounts the historical development of building code requirements for fire in the U.S. and makes the case for the need for experimental data on real-scale structural systems under realistic fire conditions in support of structural fire engineering. Further the lecture will describe the capabilities of the NFRL and provide an update on the commissioning of the new lab and plans for future tests.

Keynote lecture: ROBUSTNESS OF STEEL FRAMED STRUCTURES IN FIRE

Ian W. Burgess — 2016-01-18

Progressive collapse of a structure occurs when an initial local failure causes a sequence of failures in other elements, eventually resulting in collapse of a disproportionately large part of the structure, or even the entire building. It has been an important structural issue in the UK since the collapse of a large part of the Ronan Point apartment building in London in 1968 (The Institution of Structural
Engineers 1969). The collapse of the World Trade Center towers (Shyam Sunder et al. 2005) has attracted attention to the robustness of steel structures in fire, within which the need to evaluate the performance of the steel connections at elevated temperature has become a key topic.

Keynote lecture: VALIDATION AND VERIFICATION IN FIRE DESIGN OF STRUCTURES, A VALUABLE COST NETWORK OUTCOME

František Wald — 2016-01-18

Participants of European COST Action TU0904 Integrated Fire Engineering and Response prepared for validation and verification Benchmark studies based on their national projects. They are intended to help European researchers, educators and design engineers with their application of advanced numerical modelling for fire engineering. To complement the textual presentation of the examples the input and output data are included in MS Excel tables so that the studies can be reproduced in detail by the users of the volume. These can be downloaded from the web page fire.fsv.cvut.cz/ifer/benchmark.

A Component-based Approach to Modelling Beam Bottom Flange Buckling at Elevated Temperatures

Guan Quan — 2016-01-18

In this study, an analytical model of the combination of beam-web shear buckling and bottom-flange buckling at elevated temperatures has been created. This analytical model is able to track the force-deflection path in the post-buckling stage. A range of 3D finite element models has been created using the ABAQUS software. Comparisons have been carried out between the proposed analytical model, finite element modelling and the existing Dharma’s theoretical model. Comparisons indicate that the proposed method is able to provide with accurate predictions for Class 1 and Class 2 beams, and performs better than the existing model, especially for slender beams. A component-based model has been created based on the analytical model, and in due course to be implemented into the software Vulcan for global structural fire analysis.

A Hybrid Model to Predict Localised Cracks of Reinforced Concrete Slabs in Fire

Feiyu Liao — 2016-01-18

This paper presents a robust hybrid finite element procedure for predicting the large individual cracks within reinforced concrete floor slabs at elevated temperatures. For modelling the cracks formations and propagations within the floor slabs, the smeared crack model is used for modelling early stages of crack evolution, and then the ‘delayed extended finite element method (D-XFEM) is proposed for capturing individual big cracks within the floor slabs. The new model has been validated against previous fire test results. A series of parametric studies has been conducted on a composite floor to understand the influences of different protection conditions of the support steel beams on both global responses and cracking patterns of the composite floor under fire conditions.

Recalculation of Laboratory Tests with the Extended Zone Method

Marcus Achenbach — 2016-01-18

The Advanced Calculation Method given in EN 1992-1-2 is accepted by engineers and building authorities for the determination of the fire resistance of reinforced concrete structures. It has been developed originally for the recalculation of laboratory tests: the time of failure is calculated for a given layout of reinforcement. But in the structural analysis of concrete columns, the area of reinforcement has to be calculated for a desired fire resistance. Design methods and strategies, which are suitable for the design of concrete compression members, require constant material properties and strain limits, which are not given for the Advanced Calculation Method. Therefore Achenbach and Morgenthal have proposed an extension of the Zone Method by Hertz, suitable for the implementation in commercial design software. In this paper, this Extended Zone Method is used to recalculate laboratory tests to determine the accuracy of this method. A statistical analysis of the results is performed to evaluate the statistical key data of the Extended Zone Method.

Buckling Resistance of Axially Restrained Chord Members of Grid Structure at Elevated Temperatures

Du Yong — 2016-01-18

This paper investigates the behavior of large span grid structure exposed to a localized fire. The localized fire may generate hot smoke and thus induce non-uniform temperature distribution in the grid structure. The thermal expansion of the heated members tend to be axially restrained by the adjacent cold members thus inducing additional forces on the critical members of the grid structure. The buckling resistance of axially restrained member at elevated temperature may be obtained based on second order analysis of member with initial lateral imperfection by considering force equilibrium at deformed geometry and cross section resistance being reached. The critical temperature of the member is reached when the axial force reaches its buckling resistance. It is found that the critical temperature of members with initial lateral imperfection was higher than that without such imperfection for chord members with large slenderness ratio and high axial restraint.

Nonlinear structural analysis of a 2D cut-and-cover tunnel exposed to fire

Omid Pouran — 2016-01-18

Behaviour of cut-and-cover tunnels exposed to fire should be analysed by using a realistic model which takes account ofsimultaneous mechanical and thermal effects acting on the structure. This has been performed by 2D structural modelsfor a 2-cell tunnel with the aid of FE software package called SOFiSTiK (SOFiSTiK, 2014), in parallel, for two types of elements, beam and plate elements, as a scope of research project financed by BAST. The two considered models were levelled in terms of boundary conditions and the possible mechanical behaviour as well as mesh generation aspects.A nonlinearthermo-mechanical analysis has been performed considering pre-damaged effects on the cross sectionsby taking into account 10 and 15-minute time intervals for a whole duration of 90 minutes. The results of both models are in an acceptable agreement with each other,but they deviate from the simplified, linear-elastic calculation method considering a constant temperature gradient,DT_M = 50 K,proposed by ZTV-ING Part 5 (BASt, 2013).To improve this method, a linear interpolation of different DT_M-values with respect to the thickness of theconcrete member has been introduced.

NUMERICAL ANALYSIS OF A COMPOSITE STEEL BOX GIRDER BRIDGE IN FIRE

Nicole Leo Braxtan — 2016-01-18

Box girder bridges are becoming more common because of their ease of construction, pleasing appearance, and serviceability. Projects with curved configuration and long spans can especially benefit from these advantages. However, the industry lacks a wide range of research on multi-span steel box girder cross-sections and their response to fire events. This poses a major risk to unprotected steel bridges using a box girder design. This paper will discuss a mathematical approach to determining and classifying different failure modes of weathering steel box girder bridges subject to two fire cases. Due to the rapid increase of temperature in the thin steel members, the strength of the steel deteriorates quickly. Results show that different fire locations can greatly affect the forces that act on the individual members of the structure.

MACRO-ELEMENT MODEL OF A STEEL MOMENT FRAME SUBJECTED TO FIRE-INDUCED COLUMN LOSS

Ha Nguyen — 2016-01-18

A progressive collapse mitigation strategy is to ensure load redistribution when a column fails due to fire. The study seeks to understand whether welded unreinforced flange-bolted web (WUF-B) moment connections can effectively redistribute loads in a structural system subjected to fire when a critical column is lost. A component (or macro-element) model was derived to simulate the WUF-B connection and validated against experimental tests and high-resolution finite element (FE) models of subassemblies at room temperature and at elevated temperature. The component model was then utilized in a 2D macro FE model of a ten-story steel-framed building subjected to the loss of a column during long fire exposure. This paper presents the collapse mechanisms and quantifies structural performance based on acceptance criteria. A parametric study on location of column loss and fire occurrence is also included.

GEM – A SOFTWARE FOR STABILITY VERIFICATION OF NON-UNIFORM MEMBERS, Adaptation of the general method procedure to fire design

João Ferreira — 2016-01-18

There is currently no specific rules in Part 1-2 of Eurocode 3 for the stability verification of non-uniform members under fire conditions. For normal temperature, Part 1-1 of the same code provides a General Method to check the stability against lateral and lateral-torsional buckling for these type of members, though it requires some extensive calculations. It is here demonstrated in this paper how both problems can be addressed, by exposing a procedure that accounts for the modifications of the method at elevated temperatures, and by showing its implementation within a computer program. It is also shown how the program can be used to assess the study of the method itself, by applying it to a case of a web-tapered beam-column and comparing it to numerical results.

CHARACTERISTIC VALUE OF THE RANDOM FIRE LOAD DENSITY, Probability-based specification depending on the way how the building compartment is used

Mariusz Maslak — 2016-01-18

The algorithm that allows to specify the characteristic value of the random fire load density, depending on the way how the considered building compartment is used, is presented and discussed in detail. The proposed computational procedure is based on a probabilistic approach, the alternative in relation to the traditional methodology according to which the results obtained from the inventory of such a compartment are a basis for the evaluation. It is assumed that the sought value is estimated as the upper quantile of a Gumbel probability distribution which is set at an appropriate level of the probability of its up-crossing. The formal model described in the paper is referred to the two selected and qualitatively different design techniques which are used in practice. The first one is based on the recommendations contained in the Eurocode EN 1991-1-2, whereas the second - on the rules specified in the standard NFPA 557.

SENSITIVITY OF STRUCTURES TO FIRE DECAY PHASES, Quantitative comparison of structural components made of different materials

Thomas Gernay — 2016-01-18

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.

STRUCTURAL FIRE SAFETY OF EXISTING STEEL BUILDINGS, Possible general approach and application to the case of the intumescent coatings

Antonio Bilotta — 2016-01-18

The fire safety of the existing structures is very important from the socio-economic point of view and has high social impact for civil, industrial, and commercial buildings. The verification of the minimum fire resistance of civil structures is done through some regulations, drafted to ensure occupant and rescue teams safety as well as a limited structural damage. These national fire rules are not always easily applicable to existing buildings. The purpose of this paper is to provide guidance about the structural analysis of existing buildings exposed to fire, with particular reference to steel buildings protected with intumescent coatings.

CONTRIBUTION OF NON-STRUCTURAL CONCRETE WALLS TO THE FIRE RESISTANCE OF UNPROTECTED STEEL FRAMES

Tom Molkens — 2016-01-18

In the scope of a new industrial building, an R60 fire resistance criterion was requested by the local fire brigade for the steel structure supporting non-structural EI60 concrete walls. On the basis of an investigation conducted after an actual fire in 2008, it was presumed possible to satisfy this R60 criterion using this type of unprotected steel frame. A 2D thermo-plastic model was set up, taking into account the thermal contribution of concrete walls, to limit excessive steel temperatures of the bearing elements. A void was considered between the concrete and the web of the middle columns to simulate real construction works as much as possible. The nominal ISO-834 fire was applied separately in each bay on the exposed parts of the elements. By using fixed column bases in case of fire, the structure can withstand up to 120 minutes of ISO fire i.e. far beyond the collapse of the primary structure subjected to fire. To avoid discussions about the local impact of a real fire, the investigation was extended to columns subjected to a local fire.

ANALYSIS OF A CONCRETE BUILDING EXPOSED TO NATURAL FIRE

Ana Sauca — 2016-01-18

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.

PERFORMANCE BASED COUPLED CFD-FEM ANALYSIS OF 3-BAY HIGH INDUSTRIAL HALL UNDER NATURAL FIRE

Michal Malendowski — 2016-01-18

In this paper, the main emphasis is put into showing differences between standard fire design of structural elements and performance based approach, that takes into account analysis of structure under natural fire. The exemplary structure is a 3-bay 65,0x110,0 m in plane and 22,0 m high industrial hall with heavy cranes. Because of the significant volume with respect to fire load, there is a low probability that the fully developed fire can occur, nonetheless regarding technological process, a significant local fire could take place and affect the neighbour structure. The most complex approach used in this work is based on coupled CFD-FEM analysis of influence of local fire onto structure.Fire exposure of structural elements is calculated by the coupling scripts, taking into account real heat exposure of section by using adiabatic surface temperature approach.

DETERMINING THE FIRE RATING OF CONCRETE STRUCTURES, Case study of using a probabilistic approach and travelling fires

Tad-Song Kho — 2016-01-18

As part of a refurbishment the height of a building in London is to be increased resulting in a change of the fire rating of the existing level from R60 to R90 as per prescriptive guidance. To investigate whether the inherent fire resistance of the structure would be sufficient a state-of-the-art probabilistic approach was adopted, with the approach extended to consider 2D heat-transfer to concrete elements. After determining the required reliability of the structure based on an acceptable risk level, a Monte-Carlo assessment was conducted. This considered for the proposed internal layouts and determined the range of input parameters to be randomly varied in order to define the required range of design fires analysed. The assessment demonstrated that the inherent structural fire resistance would provide sufficient structural reliability for the new use of the building and that no additional fire protection was required to the concrete frame.

PERFORMANCE-BASED FIRE DESIGN OF STEEL STRUCTURES OF HELSINKI OLYMPIC STADIUM

Mikko Salminen — 2016-01-18

This paper presents an overview of the fire safety analysis conducted for the steel trusses of Helsinki Olympic Stadium stand. The analysis were conducted using advanced calculation models (FDS and SAFIR). It is shown that the predefined design solution (R60 fire protection with sprinklers) can be replaced by fire protection to class R15 (no sprinkler system) without sacrificing safety when some other passive protection means are applied. The good design solution in this case required highly iterative design process and smooth co-operation between client, architects, structural engineers and fire safety consultants.

SHEAR BUCKLING EVALUATION IN STEEL PLATE GIRDERS WITH RIGID END POSTS SUBJECTED TO ELEVATED TEMPERATURES

André Reis — 2016-01-18

The current study intends to analyse the behaviour of steel plate girders with rigid end posts subjected to elevated temperatures, aiming the assessment of the ultimate shear strength in case of fire. A parametric numerical study was performed involving a wide range of cross-section’s dimensions, plate girders’ aspect ratios and steel grades. Plate girders were numerically tested at both normal and elevated temperature, being considered three different uniform temperatures. The influence of the geometrical imperfections, as well as the residual stresses, was taken into account. Finally, the numerical results were compared to the Eurocode 3 (EC3) prescriptions, adapted to fire situation by the direct application of the reduction factors for the stress-strain relationship of steel at elevated temperatures. It was shown that the EC3 design rules should be improved because they are not conservative, conducting to unsafe results.

PERFORMANCE-BASED ANALYSIS OF PLANAR STEEL FRAME IN FIRE, The effect of different types of thermal insulation

Anita Treven — 2016-01-18

The paper presents a performance-based analysis of a planar steel frame exposed to natural fire conditions, if protected with different types of insulation.Bare steel elements, and elements protected with intumescent coating or insulation boards are considered. Two fire scenarios and two material models for steel, with and without the consideration of viscous creep, are applied in order to observe the effect of viscous creep. The analysis consists of three steps: (i) the determination of fire curves, (ii) the thermal analysis, and (iii) the mechanical analysis. Theexpansion of intumescent coating as well as heat flux within the voidspace between the steel surface and the insulation boards are also considered. It is shown that the choice of the thermal insulation has a significant effect on the mechanical response of the frame.

INVESTIGATION ACTIVITY ABOUT A COLLAPSED STEEL STRUCTURE SUBJECTED TO A REAL FIRE, Fire scenarios and structural behaviour of a real steel structure

Iolanda Del Prete — 2016-01-18

The paper describes the behaviour ofa real steel structure collapsed under a fire event. 3D structural analyses were performed with SAFIR program (J-M Franssen, 2005). Different modellingare implemented with some fire load models and analyses of thebehaviour of the whole structure. The main purpose of this work was to investigate the failure types of a warehouse structure under fire conditions. Different fire conditions were applied to the steel frame sections, with ISOcurve (ISO EN 834-8:2002) and zone model approach. The analyses show that with unprotected steel sections, horizontal structures are more critical than columns. Trough applying a performance basedapproach,structure has 30 minutes of fire resistance.

PARAMETRIC STUDY ON THE LATERAL TORSIONAL BUCKLING OF STAINLESS STEEL I BEAMS WITH CLASS 4 CROSS-SECTIONS IN CASE OF FIRE

Nuno Lopes — 2016-01-18

For predicting the behaviour of beams with thin-walled I sections, named Class 4 in Eurocode 3 (EC3), it is necessary to account for the occurrence of both local and lateral torsional buckling (LTB). These instability phenomena, which are intensified at elevated temperatures, should be accurately considered in design rules. The fire design guidelines for stainless steel members, given in Part 1-2 of EC3, propose the use of the same formulae developed for carbon steel (CS) elements. However, these two materials have different constitutive laws, leading to believe that the use of those formulae should be validated. This work presents a parametric numerical study on the behaviour of stainless steel beams with Class 4 I sections at elevated temperatures. The influences of several parameters such as stainless steel grade, loading type and cross section slenderness are evaluated, and comparisons between the obtained numerical results and EC3 rules are presented.

STRUCTURAL FIRE BEHAVIOUR OF Z PURLINS

Ivo Schwarz — 2016-01-18

Cold-formed sections are very common and efficient as secondary load-caring structural members. But the current European design standard EN 1993-1-2 sets the limiting temperature for the Class 4 sections to 350°C which is generallyvery conservative approach.This paper is focused on the thin-walled profilebehaviourin case offire. In particular, the paper describes transition from the beam to fibre behaviour of a Z purlin. A sophisticated shell element FE model is shown and compared to the test. Later, a more practical (Engineering) model neglecting the bending stiffness entirely is made and compared to the previous results. The conclusions show, that such simplified description of real behaviour is possible to be used after the bending capacity of the member is exceeded and predicts the forces to connection well.

PARAMETRIC STUDY ON THE FIRE RESISTANCE OF STEEL COLUMNS WITH COLD-FORMED LIPPED CHANNEL SECTIONS

Flávio Arrais — 2016-01-18

Steel structural elements with cold-formed thin-walled sections are becoming increasingly common in buildings due to their lightness and ability to support large spans. In these members, local, distortional and global instabilities are important common failure modes. At high temperatures, these instability phenomena are intensified. This paper presents a numerical study on the behaviour of columns with cold-formed C-sections in case of fire when subjected to compression. A parametric study, considering different steel grades, temperatures and different cross-sections with different slendernesses, is presented. Comparisons are also made between the numerical results and analytical design rules, such as the EN1993-1-2, using its Annex E or its French National Annex, where a different constitutive law is recommended for cold-formed profiles. It is possible to conclude that the simple calculation rules are on the safe side but sometimes too conservative.

EXPERIMENTAL STUDIES OF UNPROTECTED AND PROTECTED STEEL STRUCTURES UNDER FIRE

Véronique Saulnier — 2016-01-18

Preliminary fire experimental tests have been carried out on steel plates protected with intumescent coating.

The tests evaluated and measured the heating of steel plates with various geometrical configurations: shape, size. A first test on an equal leg angle section showed interesting results with different coating expansion on the faces of the section.

The second test campaign is done with different protections to compare behaviors of four steel plates. The first objective is to set up an experimental protocol for future tests. Those results are used to evaluate analytical prevision of steel plate temperature with and without fire protection.

EXPERIMENTAL RESEARCH ON T-STUBS UNDER ELEVATED TEMPERATURES

Ioan Both — 2016-01-18

Bolted end plate connections are widely used in multi-storey steel frame structures. Their design is based on the component method, which evaluates the behaviour of the basic components through equivalent T-stubs, to model the tension zone that constitutes the most relevant source of deformability. The paper presents the results of an experimental research on bolted T-stubs, tested under elevated temperatures, in normal and high strain rate loading conditions. The influence of the loading rate on the resistance and ductility of the T-stubs subjected to elevated temperatures is emphasized.

FIRE DESIGN OF STEEL BEAMS WITH SLENDER CROSS-SECTION, The influence of loading

Carlos Couto — 2016-01-18

The present paper addresses the study of laterally unrestrained steel beams with slendercross-sections for the case of fire with special focus on the influence of loading. A numerical investigation of several beams submitted to triangular and bi-triangular end-moment distribution and uniformly distributed loads is carried out at elevated temperatures usingshell finite elements. The results are compared with the existing simplified beam design rules of Part 1.2 of Eurocode 3 and recent developments on the subject, as well as the utilization of the factor “f” which was developed to take into account the non-uniform bending diagrams but for stocky cross-sections (Class 1 and 2).

PERFORMANCE BASED DESIGN OF UNBRACED STEEL FRAMES EXPOSED TO NATURAL FIRE SCENARIOS

Carlos Couto — 2016-01-18

According to the Eurocode 3 Part 1-2 (EN1993-1-2) (CEN 2005b), it is possible for structural engineers to consider physical based thermal actions and to do performance based design instead of using prescriptive rules based on nominal fire curves. However, some uncertainties remain in the use of such approaches. This study focus on the clarification of the use of the simplified design methods to assess the fire resistance of unbraced steel frames exposed to fire. On the other hand, a recent study (Couto et al. 2013) suggests the use of a buckling coefficient of 1.0 for all the columns except those belonging to the first storey of a pinned framed where 2.0 should be taken instead and it is unclear if the consideration of such values for the buckling lengths is adequate when using performance based designs.

In this study, a comparison is made between simple and advanced calculation models and it is demonstrated that the simple design methods, using the suggested buckling coefficients to calculate the fire resistance of the frames are safe sided when compared to the use of advanced calculations using the finite element method (FEM).

OPTIMUM RELIABILITY OF A STEEL TAPERED PORTAL FRAME STRUCTURE EXPOSED TO FIRE

Tamás Balogh — 2016-01-18

In this study, the optimum reliability of a tapered steel portal frame structure is presented for several cases. The aim of the research is to define target reliability indices for fire design situation since some research works (Balogh and Vigh, 2015a; 2015b) pointed that the achievable reliability (with using the prescriptive rules of Eurocode standards) is lower in extreme and seismic design situations than the suggested target value in (EN0, 2002). It seems that the target reliability indices of (JCSS, 2000) are preferable in these cases. In this paper, the optimum reliability is investigated as described in (Holickỳ, 2011), but total cost function is formulated with two decisive variables with respect to the amount of active and passive safety measures. The structural reliability is obtained with the help of a complex FORM (First Order Reliability Method) algorithm. The results of this investigation can help also to answer the question, whether active or passive safety measures are more effective tools to achieve optimal solutions in case of fire design of steel portal frames.

POST-FIRE SAFETY OF CONCRETE COLUMNS, An engineering-oriented reliability-based assessment tool

Ruben Van Coile — 2016-01-18

Concrete insulation properties and chemo-physical stability up to 400-500°C generally prevents concrete structures from collapsing in fire. Consequently, the safety assessment of reinforced concrete members – and specifically columns – is a must past any severe fire. This post-fire assessment should be based on reliability considerations, as many uncertainties are associated with both the fire evolution and the residual mechanical properties of the materials. The reliability considerations should clarify whether the column has an adequate safety level for its intended post-fire use. An easy-to-use reliability-based assessment method is presented in this paper to determine the bearing capacity of a reinforce concrete column after a fire, and the safety performance of the method is investigated. The proposed method is shown to be at the same time easy to use and very reliable.

A PARAMETRIC STUDY ON BUCKLING OF R/C COLUMNS EXPOSED TO FIRE

Lijie Wang — 2016-01-18

Buckling of concrete columns is a major issue in fire design, since heating of the columns will result in loss of stiffness and strength in the outer concrete layers. In the Dutch concrete code NEN 6720 (NEN, 1995), a quasi-linear theory of elasticity (KLE) method is provided for columns at ambient temperature. However, no literature is available showing whether this method could be adopted for elevated temperatures. Hence, an efficient calculation tool is needed to validate the applicability of this method in case of fire. As a first step, a cross-sectional calculation tool is introduced to calculate interaction curves of columns at ambient temperature. Further, the interaction diagrams obtained with this numerical method as well as the stiffness method provided in (Eurocode, 2004) and the KLE method are compared. Then, an assumed formula in the KLE-method for the nominal stiffness calculation is discussed considering interaction curves of columns in case of an ISO 834 fire. Finally, parameters like the fire duration and the slenderness ratio are investigated.

STRENGTHENING HEAT DAMAGED REINFORCED CONCRETE BEAMS USING GLASS FIBER-REINFORCED POLYMER (GFRP) LAMINATES

Danie Roy — 2016-01-18

A series of 21 reinforced concrete T- beams of length 1400 mm were cast using normal strength concrete. After 90 days of ageing, the beams were heated to 600°C and 900°C temperatures in an electric furnace. While three control beams were treated at room temperature, eighteen beams were heat damaged. The heat damaged beams were strengthened with FRP laminates and then tested until complete failure. Two different strengthening patterns of glass fiber reinforced polymer (GFRP) strengthening materials were used. The strengthened beams were then tested in a loading frame under 4 point loading condition. The load-deflection curves for the beams were examined to evaluate the capability of various strengthening patterns. Structural performance of various strengthening patterns were gauged in terms of failure mode, flexural strength, secant stiffness and the energy absorption capacity i.e. area under the load-displacement curve. It was observed that the beams exposed to different temperatures experienced a reduction in ultimate load carrying capacity ranging from 14 % to 61%. The secant stiffness and energy dissipation were reduced in the range of 34% to 56% and 10% to 41% respectively. The study shows that GFRP wraps were quite capable of restoring the flexural strength of heat damaged beams.

DEFLECTION RESPONSE OF REINFORCED CONCRETE SLABS TESTED IN PUNCHING SHEAR IN FIRE

Holly Smith — 2016-01-18

Flat slab-column punching shear specimens were tested under combined load and fire exposure, with varying edge restraint conditions. The slabs deflected away from the heat source (in the direction of loading) at all stages of the tests. This paper examines this unusual deflection behaviour, although no definitive reason for this unexpected behaviour has been found.

BUCKLING LOAD OF RC COLUMNS EXPOSED TO ISO FIRE LOAD, The influence of the cross-sectional dimensions

Urška Bajc — 2016-01-18

The influence of the cross-sectional dimensions on the buckling load capacity of reinforced concrete column exposed to ISO fire load is presented. The fire analysis is divided in two separate phases. In the first phase, the calculation of the temperatures over the cross-section of the concrete column is performed. Here more advanced hygro-thermal analysis is executed to take into account the influence of moisture on the distribution of the temperatures. In the second step of the fire analysis, the mechanical analysis is performed. The mechanical and thermal properties of concrete and reinforcement at elevated temperatures are used in accordance with EN 1992-1-2 (2004). For two different cross-sections, the parametric study has been performed. The critical buckling time and critical buckling capacity as a function of a load and slenderness of reinforced concrete column have been determined.

REACTION OF R/C SLABS CROSS-SECTIONS TO FIRE, Calculation of simplified substitute temperature loads induced by an unsteady heat flow

Robert Kowalski — 2016-01-18

An important issue in advanced analysis of reinforced concrete structures exposed to fire is to determine the response of structural elements (cross-sections) to the effect of high temperature. The unsteady heat flow results in a nonlinear temperature distribution. In practical structural calculations performed by simplified computer programs the average temperature value and the appropriate temperature gradient are used. This paper presents substitute values of these parameters and detailed analysis of nonlinear temperature distribution in 20, 25, 30 cm thick reinforced concrete slabs exposed to one-sided standard fire.

FIRE ANALYSIS OF CURVED REINFORCED CONCRETE BEAM

Dušan Ružić — 2016-01-18

In the present study the fire analysis of a curved reinforced concrete beam exposed to concrete spalling is presented. Due to the complexity of physical and chemical processes in concrete at elevated temperatures, the proposed numerical model is divided into two consecutive mathematically uncoupled phases. In the second phase of the fire analysis a partially coupled numerical model is introduced in order to evaluate the effect of concrete spalling on the behaviour of curved RC beam in fire. In addition, the effect of depth, time development and the length of spalling area on the fire resistance of a curved RC beam is discussed.

PRESTRESSED MEMBERS UNDER NATURAL FIRES: A PRELIMINARY STUDY ON THE RESIDUAL BEHAVIOUR

Natasa Kalaba — 2016-01-18

The present work is aimed at investigating the residual behaviour of prestressed concrete members exposed to natural fires, since experience has shown that substantial losses of the load bearing capacity may take place during the cooling phase. This topic is of great practical significance, because the knowledge of the residual response can help the engineers to decide whether a structure can be refurbished after being exposed to fire, with minor costs, or whether demolition is inevitable.Sequentially coupled thermo-mechanical analysis was performed on typical inverted T and double T-beam sections, subjected to heating and subsequent cooling.The results show that the residual deflection is primarily governed by the load level and the section shape and that the magnitude of the residual deflection can be even several times higher than the initial value.

FIRE RESISTANCE FOR THIN-WEBBED CONCRETE AND MASONRY ELEMENTS

György L. Balázs — 2016-01-18

Deterioration of material characteristics and structural performance highly depends on constituents and temperature history. Material composition can also highly influence structural behaviour of elements. Thickness of web can be critical for high temperatures. The same situation is for interjoist elements (concrete or brick) between precast roof girders.

First part of our study was to improve fire resistance by structural elements with a typical thin web. Our experimental study included fire tests on various concrete mixes and fire tests of the girder with simultaneous application of load. Second part of our study was to summarize the result of real fire cases for girder-slab systems with concrete or brick interjoists.

ANALYSIS OF COMPOSITE BUILDINGS UNDER FIRE CONDITIONS

Shuyuan Lin — 2016-01-18

In this paper, the performances of a generic three dimensional 45m x 45m composite floor subjected to ISO834 Fire and Natural Fire are investigated. The influences of reinforcing steel mesh and vertical support conditions on the tensile membrane action of floor slabs are investigated in details. Two robust 2-node connection element models developed by the authors are used to model the behaviour of end-plate and partial end-plate connections of composite structures under fire conditions. The impact of connections on the 3D behaviour of composite floor is considered. Based on the results obtained, some design recommendations are proposed to enhance the fire safety design of composite buildings.

THE MECHANICS OF TENSILE MEMBRANE ACTION IN COMPOSITE SLABS AT HIGH TEMPERATURES

Ali Alskeif — 2016-01-18

The mechanics of tensile membrane action of thinlightly-reinforced concrete slabs has been re-examined during the last two years.The re-examination is based on large-deflection plastic yield-line analysis, applied to flat slabs. As deflection increases beyond the optimum yield-line pattern, tensile membrane action is mobilized and further load carrying capacity is provided. This paper represents an extension of this re-examination to include composite slabs at high temperatures. As temperature increases, the unprotected downstand steel beams significantly lose capacity, allowing for further deflection until the overall capacity degrades to the applied load. Tensile membrane action then allows further increase of steel temperature until a maximum is reached.

STUDY OF THE FIRE PERFORMANCE OF HYBRID STEEL-TIMBER CONNECTIONS WITH FULL-SCALE TESTS AND FINITE ELEMENT MODELLING

Aaron O. Akotuah — 2016-01-18

Connection design is critical in timber buildings since the connections tend to have lower strength than the structural members themselves and they tend to fail in a brittle manner. The effect of connection geometry on the fire performance of a hybrid steel-timber shear connection is investigated by full-scale testing. These tests were conducted by exposing the test specimens to the standard time-temperature curve defined by CAN/ULC-S101 (CAN/ULC-S101, 2007). Test results showed that the fire resistance of these connections depends on the load ratio, the type of connection and the relative exposure of the steel plate to fire. Finite element models of the connections under fire were constructed using ABAQUS/CAE and these were validated using the test results. These numerical model results correlate well with test results with ±8.32% variation.

PREDICTION OF RESIDUAL STRENGTH OF COMPOSITE COLUMNS USING FEM ANALYSIS

Sun-Hee Kim — 2016-01-18

Fires in buildings cause not only economic losses but also many casualties. A prolonged fire involves the possibility of the damage to structural members, which calls for the repair or reinforcement of the building. Since it is critical to decide whether structural members need reinforcement, the technique to determine the degree of the damage to structural members caused by a fire should be established. CFT columns are superior to generic steel columns in terms of fire resistance performance thanks to the thermal storage effect of the concrete inside the columns. Studies have suggested how to reinforce the concrete to further improve the structural strength and fire resistance performance of CFT columns. When CFT columns of a building are damaged by a fire, it is required to determine preciously how serious the structural deterioration of the members is. The purpose of this study is to evaluate the residual strength of CFT columns damaged by a fire by evaluating the temperature distribution inside the columns and determining the degree of deterioration in the load capacity of concrete and steel in relation to temperature distribution.

A FULLY GENERALISED APPROACH TO MODELLING FIRE RESPONSE OF STEEL-RC COMPOSITE STRUCTURES

Jerneja Kolšek — 2016-01-18

In the paper a new generalised three–phase finite–element numerical model for the fire analysis of beam–like steel–concrete composite structures is presented. In addition, the influence of contact stiffness in a standard trapezoidal RC plate to its ultimate fire resistance is presented employing the proposed numerical procedure.

DEVELOPMENNT OF A COMPOSITE SLAB BREAK-ELEMENT FOR THE ANALYSIS OF COMPOSITE FRAMES IN FIRE

Mohammadali Javaheriafif — 2016-01-18

This research is intended to predict the inevitable through-depth crack development in a composite slab, across its area and in particular around its edges at large deflection. Based on previous work, a theoretical model has been proposed to simulate the local behaviour of slab beyond initial cracking. The model has been successfully implemented in the software VULCAN as a new line element. Comparisons between the existing theoretical model and FE modelling have shown that the proposed element provides a sufficient level of accuracy beyond initial cracking. However, further improvement is needed to enable a precise investigation of the local and global behaviour of composite slab systems, and the influence of through-depth cracking on the slab’s performance.

INTERACTION DIAGRAMS AXIAL FORCE-BENDING MOMENT FOR FIRE EXPOSED STEEL-CONCRETE COMPOSITE SECTIONS

Milivoje Milanovic — 2016-01-18

The bearing capacity of the column cross section can be determined from the interaction diagram moment-axial force (M–N). Fire induced temperatures cause reduction of the load-bearing characteristics of the constitutive materials, steel and concrete, and this effect directly reflects on the reduction of the axial force and the bending moment that could be accepted by the column cross section, respectively the interaction diagram of the column cross section is changed. The load bearing capacity of the steel-concrete composite columns exposed to fire from all four sides and loaded by axial force and uni-axial or bi-axial bending moments, was estimated on the basis of the changes in the interaction diagrams moment-axial force amd the results are presented in this paper. Different types of composite columns made of totally or partially encased steel sections, or concrete filled hollow sections were analyzed and a detailed discussion on the effects of the shape of the cross section and the cross sectional dimensions are presented.

THE BEHAVIOUR OF SPECIAL OSB BOARDS UNDER FIRE CONDITIONS, The influence of OSB board´s fire coating on the fire resistance of light timber frame assemblies

Petr Kuklík — 2016-01-18

The paper is focused on the influence of fire resistant coatings used on OSB boards on the fire resistance of entire light timber frame wall assemblies. Two fire tests were performed in the fire test laboratory of PAVUS, a.s. in Veselí nad Lužnicí. The fire tests were performed on a load bearing wall. The wall dimensions were 3.0 (depth) x 3.0 (height) m. According to EN 1995-1-2, the calculation for fire paints and coatings is not possible. The aim of the paper is the determination of the influence of this type of coating on the OSB board’s charring rate, the determination of the start of charring of a timber stud and the fire resistance of the whole construction.

RELIABILITY OF TIMBER STRUCTURES EXPOSED TO FIRE

Mislav Stepinac — 2016-01-18

Until recently, the fire resistance of buildings was based on the ISO standard curve. ISO standard curve used by the current norm is too simple, unrealistic and lead to uneconomic situations with no guarantee of security proportional to the invested money. Unlike the fire design of the steel, concrete or composite structures, methods for fire design of timber structures have been greatly simplified. Generally, it is not necessary to check the reduction of strength in the residual section because each increase of temperature is considered small and it is ignored. Global fire safety concept of timber structures is presented according to the recommendations from Eurocode norms. Special attention was given to natural fire design with two different methods of parametric exposure which are given in EN1995-1-2.

This paper presents reliability analysis of a glulam beam in a case of fire. The limit-state functions for maximum bending stress of glulam beam in fire conditions are formed. Reliability indexes are obtained from the limit state of the beam exposed to 30 min fire. Reliability index in the Eurocodes (reliability class RC2) compared to the calculated reliability indexes obtained by the methods of reduced strength and effective section were described.

RELIABLITY OF CURVED TIMBER BEAM EXPOSED TO FIRE

Robert Pečenko — 2016-01-18

In this paper the performance based approach to determine the reliability of curved timber beam during the fire is presented. The reliability is preformed with Monte Carlo simulation method, where, in order to reduce the number of simulations, Latin hypercube sampling is applied. The uncertainties are implemented in the advanced calculation method, as randomly generated parameters for both thermal and mechanical analysis. At the end of the paper, the distribution of the mid-span displacement at 30 min, 45 min and at failure time is presented. In addition, failure time that satisfies safety requirement from the Eurocode (β > 3.8) is determined as well.

BEHAVIOUR OF ALUMINIUM STRUCTURES IN FIRE, A review

Davor Skejić — 2016-01-18

The interest in the application of aluminium as a structural material has been greatly increased in recent years. However, behaviour of aluminium structures when exposed to fire is still relatively unresearched. Due to low melting temperature of the alloy, aluminium structures have low fire resistance, but aluminium is reflective and has surface emissivity which is more than two times lower compared to carbon steel. The Eurocode facing this issue (EN 1999-1-2) is based mainly on the Eurocode for structural fire design of steel structures (EN 1993-1-2) and therefore is not fully suitable for the application on aluminium structures. Here, an overview of the structural behaviour of aluminium structures exposed to fire is given through the comparison with steel structures. As a conclusion, priorities for a future research are highlighted, which should provide a base for the next generation of modern codes for structural fire design of aluminium structures.

EXPERIMENTAL AND NUMERICAL ANALYSIS OF ULTRA HIGH PERFORMANCE CONCRETE (UHPC) MEMBERS IN CASE OF FIRE

Matthias Siemon — 2016-01-18

The research activity in progress and the advancements in concrete technology are leading to an increased use of high performance and ultra high performance concrete in structural engineering. Due to its high compressive strength and ductile behavior in combination with steel fibres, UHPC structural members can be designed as slender and light structures compared to standard concrete design. This increasingly leads to the option in architectural design to highlight the bearing capacity of the building without hiding the structural components.

In case of fire safety design a disadvantageous behavior of UHPC compared to normal strength concrete is well known and documented. The high packing density of the cement matrix is the main reason for explosive spalling behavior when exposed to fire. To avoid spalling, an appropriate amount of polypropylene fibres has to be introduced in the concrete mix design. In addition, slender and light structures are in general more sensitive to fire exposure due to the higher surface to volume ratio.

In this paper, the analysis of the thermal and mechanical material properties using experimental and numerical methods is presented. The investigations were carried out during the priority program 1182 in the research project “Theoretical and experimental determination of the high temperature behavior of ultra high performance concrete (UHPC)”, funded by the German Research Foundation (DFG), see (Schmidt 2014) and (Hosser et al. 2014).

In the project the thermal properties heat conductivity, specific heat capacity and the temperature dependent density as well as the mechanical properties like the temperature dependent stress-strain-relation and thermal expansion were experimentally determined. In addition, the optimum fibre content was determined. The findings of the project were used to develop a material model and checked against experimental results on fire exposed UHPC columns using a FE model.

PERFORMANCE OF DIFFERENT CREEP MODELS IN THE ANALYSIS OF FIRE EXPOSED STEEL MEMBERS

Neno Torić — 2016-01-18

In order to model the impact of the creep strains on the behaviour of steel in fire, several creep models have been implemented into Vulcan research code. The paper presents verifications of these creep models for fire-exposed steel against transient fire tests of simply supported steel beams with various loading arrangements, including bending combined with axial compression. In addition, a creep-free analysis of the fire tests has been performed using a newly developed creep-free methodology. Creep-free analysis is vital in explicit modelling of steel creep in fire, since most of the available material models of steel in fire were derived from transient coupon tests and inherently included creep associated with the particular heating rates used in the tests.

TESTS ON 10.9 BOLTS UNDER COMBINED TENSION AND SHEAR DURING AND AFTER FIRE

Anne K. Kawohl — 2016-01-18

Prior investigations of the load bearing capacity of bolts during fire have shown differing behaviour between bolts that were loaded by shear or by tensile loads. The interaction of the two loads has not yet been examined under fire conditions. This paper describes a preliminary test series on the post-fire performance of high-strength bolts of the property class 10.9 under combined tension and shear. The results show that how the bolt is loaded influences the load bearing capacity. It is assumed that this is also true at elevated temperatures. Further, atest set-up for experiments at elevated temperatures and a more detailed test series on the post-fire performance under combined tension and shear is presented.

EXPERIMENTAL RESEARCH OF PRECAST CONCRETE FLOOR BLOCKS WITH IMPROVED RESISTANCE TO HIGH TEMPERATURE

Dubravka Bjegovic — 2016-01-18

The paper presents possibility of usage of crushed clay bricks and roof tiles as an aggregate for concrete in precast concrete floor blocks. According to literature review, concrete with crushed brick and roof tiles as an aggregate has better thermal properties than regular concrete with natural aggregate. Applicability of concrete mixture for precast concrete blocks was tested regarding the requirements set in HRN EN 15037-2 Precast Concrete products – Beam and block floor systems – Part 2: Concrete blocks. Precast concrete blocks with crushed bricks and roof tiles were made and their mechanical properties after exposure to high temperature were tested. Based on experimental results, conclusions are made about usage of crushed bricks and roof tiles as partial replacement of natural aggregate in concrete for precast concrete blocks with improved resistance to high temperatures.

HIGH Tg FRP & CEMENTITIOUS ADHESIVE, Potential benefits in fire for NSM FRP strengthened reinforced concrete beams

Iolanda Del Prete — 2016-01-18

Near surface mounted FRP strengthening is potentially less prone to damage due tofire exposure than externally bonded FRP reinforcement (EBR), provided that: (a) an FRP strengthening material with high glass transition and decomposition temperatures (T_g andT_d, respectively); and (b) a bonding agent with low thermal conductivity and good thermal stability, are used. This paper presents a project undertaken on a specific high T_g and cementitious adhesive bonded NSM FRP strengthening system. Dynamic Mechanic Analysis (DMA) and Thermogravimetric Analysis (TGA) performed on the novel high T_g commercial CFRP bar yielded a T_g value of 220°C (based on peak) and T_d of about 360°C. Thermal conductivity tests were also performed on the cementitious grout. The results were used to better explain the failure modes of NSM FRP strengthened reinforced concrete beams at elevated temperature. The paper highlights the importance of understandingthe thermo-mechanical properties of the various constituent materials for improving the performance of FRP strengthening systems in fire.

STRAIN BEHAVIOUR OF ULTRA-HIGH-STRENGTH CONCRETE UNDER THE ELEVATED TEMPERATURE AND 0.25FCK LOADING

Gyu Yong Kim — 2016-01-18

The high-temperature creep of Ultra-High-Strength Concrete (UHSC) has been investigated in this study. The purpose of this study is to evaluated total strain and high-temperature creep at elevated temperatures under loading condition of UHSC. To evaluate the strain behaviour of UHSC at elevated temperatures, ϕ100 mm × 200 mm cylindrical specimens of UHSC with compressive strengths of 80, 130 and 180 MPa concrete were heated to 700 °C at a rate of 1 °C/min. The total strain and high-temperature-creep were measured under the loading condition of 0.25 of the compressive strength at room temperature. As results, Total strain of UHSC increased showing shrinkage with increasing compressive strength. The high-temperature creep of UHSC increased with the temperature and higher level of compressive strength showed bigger high-temperature creep.

RESIDUAL STRENGTH OF STRUCTURAL STEELS: SN400, SM520 AND SM570

In-Rak Choi — 2016-01-18

This paper presents post-fire mechanical properties of mild to high-strength steels commonly used in building structures in Korea. Steel is one of the main materials for building construction due to fast construction, light weight, and high seismic resistance. However, steel usually loses its strength and stiffness at elevated temperatures, especially over 600°C. But steel can regain some of its original mechanical properties after cooling down from the fire. Therefore, it is important to accurately evaluate the reliable performance of steel to reuse or repair the structures. For this reason, an experimental study was performed to examine the post-fire mechanical properties of steel plates SN400, SM520 and SM570 after cooling down from elevated temperatures up to 900°C. The post-fire stress-strain curves, elastic modulus, yield and ultimate strengths and residual factors were obtained and discussed.

TO TESTING OF STEEL FIBRE REINFORCED CONCRETE AT ELEVATED TEMPERATURE

Vadims Goremikins — 2016-01-18

Addition of steel fibres improves properties of concrete. The lack of information considering tensile and post cracking behaviour of SFRC at elevated temperatures is an obstacle on the wide use of this composite material. This work presents an experimental study of steel fibre reinforced concrete subjected to high temperature. Compressive strength, split tensile strength and ultimate bending strength were evaluated. The specimens were heated by ceramic heaters and then repacked for testing.

REUSED TYRE POLYMER FIBRE FOR FIRE-SPALLING MITIGATION

Shan-Shan Huang — 2016-01-18

Polypropylene fibres (PPF) are used in concrete principally to reduce plastic shrinkage cracking, but also to prevent explosive spalling of concrete exposed to fire. In the EU alone, an estimated 75,000 tonnes of virgin PPF are used each year. At the same time an estimated 63,000 tonnes of polymer fibres are recovered from end-of-life tyres, which are agglomerated and too contaminated with rubber to find any alternative use; currently these are mainly disposed of by incineration. The authors have initiated a study on the feasibility of reusing tyre polymer fibres in fresh concrete to mitigate fire-induced spalling. If successful, this will permit replacement of the virgin PPF currently used with a reused product of equal or superior performance. A preliminary experimental investigation is presented in this paper. High-strength concrete cubes/slabs have been tested under thermo-mechanical loading. This study has shown promising results; the specimens with the tyre polymer fibres have shown lower vulnerability to spalling than those of plain concrete.

EFFECTS OF A TRAVELLING FIRE ON A CONCRETE COLUMN – TISOVA FIRE TEST

David Rush — 2016-01-18

The Tisova Fire Test was a large fire test conducted in the Czech Republic in January 2015 inside of a 4-storey concrete frame building, with concrete and composite deck floors. The test compartment was on the ground floor and the fire compartment had a total area of ca. 230m² with a height of 4.4m. The fire compartment included four columns from the original 1958 concrete construction, one of which was instrumented for temperatures, chosen due to its higher likelihood of observable structural response both during and after the fire. This paper presents selected results of the test, concentrating on the thermal environment around the column showing the variability of temperaturesthrough the compartment height. The paper also present the columns thermal response, as well as a post-fire assessments of the columns visual condition.

VERIFICATION OF NUMERICAL MODEL OF FIRE AND SMOKE DEVELOPMENT IN RAILWAY TUNNEL

Kamila Horová — 2016-01-18

Simulation of fire spread and development of toxic gases during a fire accident in a railway tunnel allows prepare and validate models of safe evacuation of people. Highly complex problem of fire dynamics in a tunnel can be solved by the aid of numerical models based on CFD method. In order to check the quality of prediction models the procedure of verification is used. A relatively simple model of a single track railway tunnel is solved in two independent codes - FDS and Smart Fire. Accuracy of the model prediction is verified by the aid of gas temperature resolution along the tunnel length. To estimate an error based on different mesh resolutions of numerical model, calculation of the same model is carried out using different mesh density.

FIRE DYNAMICS IN FAÇADE FIRE TESTS, Measurement, modeling and repeatability

Johan Anderson — 2016-01-18

Presented is a comparison between full-scale façade tests where SP Fire 105 and BS 8414-1 were used regarding repeatability and the use of modelling to discern changes in the set-ups. Results show that the air movements around the test set-up (the wind) may have a significant impact on the tests and that the heat exposure to the façade surface will among other depend on the thickness of the test specimen. Also demonstrated was that good results could be obtained by modelling of the façade fire tests giving us the opportunity to use these methods to determine the effect of a change in the experimental setup.

MODELLING OF FIRE IN AN OPEN CAR PARK

Timea Márton — 2016-01-18

Steel car parks exhibit high vulnerability to fire, as a consequence of the degradation of the steel mechanical properties at high temperatures and of the combustible type and amount. Real fire accidents in open car parks demonstrated a much faster and extended fire spread than predictions, assuming that a fire spread rate of 12 min and consider at most 3-4 vehicles on fire at the same time. Fire Dynamic Simulator (FDS) is applied in this current paper to study fire spread between cars. The outcomes of the investigations show that the fire spread is strongly influenced by the geometrical layout and that the distance between cars plays a determinant role on the fire spread rate and ignition of adjacent cars. In particular it was found that the fire spread can be faster than 12 minutes in the case of the cars parked 40 and 60 cm from each other.

INFLUENCE OF SURROUNDING BOUNDARIES ON FIRE COMPARTMENT TEMPERATURE

Alexandra Byström — 2016-01-18

This paper shows and demonstrates how an analysis of the energy and mass balance of a fully developed (ventilation controlled) compartment fire can be used as a basis for simple and accurate predictions of fire temperatures. The model has been applied on compartments of light weight concrete structures. A finite element FE analysis has been used to solve the heat transfer equation. Effects of moisture were considered for material properties of the surrounding structure. The results were validated with experiments. The model then accurately predicted the fire temperatures and among other things it showed the influence of moisture in the surrounding structure on the fire temperature. Parametric temperature curves according to EN 1991-1-2, 2002 were shown to overestimate the fire temperature.

FIRE PERFORMANCE OF COMPOSITE-PANEL SEPARATION WALLS

Miroslav Smolka — 2016-01-18

Composite panel walls with both combustible and non-combustible cores were subjected to fire resistance test to EN 1364-1. The results revealed that the combustible-core panels started emitting smoke on the unexposed side due to the presence of joints between panels. In some cases the smoke emission started early after the start for the fire exposure. The start of the smoke production period appeared to depend on the fixation of the panels to the furnace frame; three or four sides fixed as per EN 1364-1. The amounts of smoke released indicate that although smoke leakage/production criterion is not currently part of the standard fire-resistance testing protocol it should be assessed when construction elements with combustible components are tested. Otherwise such a barrier may not be considered as a smoke-safe separating element, because model FED calculations indicate a potential threat to the occupants on the unexposed side at a certain set of conditions.

IMPROVED TRAVELLING FIRES METHODOLOGY - iTFM

Egle Rackauskaite — 2016-01-18

Current design codes and most of the understanding of behaviour of structures in fire are based on small enclosure fires. The World Trade Centre Tower fires in 2001 have highlighted the need of a more realistic design tools to represent fires in large compartments. Following the events Travelling Fires Methodology (TFM) has been developed by Stern-Gottfried and Rein to account for the travelling nature of fires. In this study the TFM is refined to account for more realistic fire dynamics. Equations are introduced to reduce the range of possible fire sizes. The analytical equations describing reducing far-field temperatures are presented. The concept of flame flapping is introduced to account for variation of temperatures in the near-field region due to natural fire oscillations. The need for more fundamental research and experimental evidence in large compartments for further development of and improvements on TFMis highlighted.

FIRES IN WOOD INDUSTRY

Nenad Papić — 2016-01-18

In recent years, there were a few fires of equipments in wood industry in Croatia, after which in fire scene investigation and determination of fire cause working, as a part of team, experts from Forensic Science Centre „Ivan Vučetić“ (FSC „Ivan Vučetić“). One of this fires in wood industry was the fire in the “Wood Industry Bohor“. In the paper is described the manner of work of the expert witnesses when there determined the cause of fire in industrial equipments. There are given methods of determining the cause of fire and point at characteristic defects which may cause a fire.

SANDWICH PANELS – BEHAVIOR IN FIRE BASED ON FIRE RESISTANCE TESTS

Paweł Roszkowski — 2016-01-18

Sandwich panel is the material that is easy and quickly to install. Basing on a great experience in the area of determination of the fire resistance class of construction building elements the authors describe the properties and behavior of building elements made of the sandwich panels exposed to fire. The article presents the results of fire resistance tests carried out in accordance with EN 1364-1 non-bearing walls made of sandwich panels with use of different cores.

The following parameters were analyzed: temperature rise on unexposed side (I – thermal insulation), integrity (E) depending on the orientations and on the width of the sandwich panels, deflection depending on the thickness of the boards. Conclusions were made on the base of the analysis from fire resistance tests.

COMPARISON OF THE MEASUREMENT RESULTS OF LARGE SCALE FAÇADE FIRE TESTS USING IR THERMOGRAPHY AND THERMOCOUPLES

Bojan Milovanović — 2016-01-18

In this paper the effectiveness of using a high temperature range, microbolometer infrared (IR) camera for the study of large scale façade fire tests will be investigated. The long-wave microbolometer camera has the ability to measure temperatures but the smoke and the flames itself influence the measurement results. This is due to the absorption of the infrared radiation by both smoke and flames while at the same time they emit radiation due to their high temperatures. The purpose of this study is to demonstrate the usefulness of an IR camera when studying large scale façade fire tests. The problems are difficulties in verification how representative measurements are and consequently it is not clear and sure if conditions for reliable measurements are really fulfilled. The measurement results acquired by the IR camera will be compared to the measurement results acquired by the thermocouples 1 mm, 3 mm in diameter and plate thermometers.

MASS LOSS AND FLAMMABILITY OF INSULATION MATERIALS USED IN SANDWICH PANELS DURING THE PRE-FLASHOVER PHASE OF FIRE

L.L. de Kluiver — 2016-01-18

In this study, the mass-loss and flammability limits of different sandwich panels and their cores (PUR, PIR, stone wool, EPS and XPS) are studied separately using a special developed furnace. The focus is on the pre-flashover phase of fire (up to 400°C), because exceeding the lower flammability limit in this phase may lead to a smoke layer explosion, a hazardous situation for an offensive intervention by the fire brigade. The research has shown that the actual mass-loss of synthetic and stone wool based cores is comparable up to 300°C. From 300°C onwards, the mass-loss of PUR panels is significant. EPS and XPS cores become fluid before pyrolysis starts. Furthermore delamination of the panels can be observed at exposure to temperatures above 250°C for the synthetic and 350°C for the mineral wool panels. The lower flammability limits have been established experimentally at 39% m/m (PUR) and 36% m/m (PS) of the pyrolysis gasses on the air mass, respectively. For PIR and mineral wool no flammability limits could be established.

FROM ENERGY STRATEGIES THROUGH ENERGY RETROFITTING TO FIRE SAFETY OF BUILDINGS

Ivana Banjad Pečur — 2016-01-18

European policy is reflected in a 10-year strategy called 2020 proposed to revive European economy and it is deeply interconnected with Energy Performance of Building Directive and its Recast. Republic of Croatia, as an EU member state, is aligning its national energy policy with European policy. By boosting energy retrofitting of existing and constructing energy efficient new buildings, thermally enhanced building envelope represents significantly increased fire load on building, thus fire safety becomes inevitable segment of energy efficiency of buildings. Croatia has no national test method for determining fire performance of building façade, while harmonized EN test method is currently being developed. In this paper an overview and comparison of BS 8414-1:2002 and DIN Entwurf 4102-20 standards will be presented, since they are proposed as a basis for future harmonized EN test method. For similar configuration of test specimens, BS 8414-1:2002 defines significantly more severe heat exposure compared to DIN Entwurf 4102-20.

COMPARTMENT AND FAÇADE LARGE SCALE TESTS: BEHAVIOR COMPARISON OF DIFFERENT INSULATING MATERIALS IN CASE OF FIRE

Elsa Pastor — 2016-01-18

Fire safety community is currently concerned about the response of some widely used insulating materials in case of fire, due to the fact that existing regulations do not show how these materials behave in real conditions, which in some applications may be indeed critical. Within this context, several institutions have recently carried out large-scale tests with the aim of testing such insulator’s contribution to fire growth. In this paper we present a set of large scale tests of compartment and façade fires involving materials and configurations of different nature. Our experiments provided evidence that mineral wool insulator preserves its properties in case of fire, whilst other polymeric-type insulators contribute to fire growth in conditions close to the ones present in real fires.

FIRE RESISTANCE OF ENERGY EFFICIENT FLOOR STRUCTURES

Meri Cvetkovska — 2016-01-18

This paper presents the numerically achieved results for the fire resistance of several types of floor structures which are mostly used in our residential and rural buildings and in same time fulfil the energy efficient criteria, as: semi-prefabricated reinforced concrete slabs system FERT and STIRODOM (with infill of extruded polystyrene -XPS), timber-concrete composite floor structure and traditional timber floor structure. The solid RC slab was analysed only for comparison. Using the computer programs SAFIR, the effect of the intensity of the permanent and variable actions and the effect of the thermal isolation on the fire resistance of simply supported slabs were analyzed. The fire resistance was defined with respect to the criteria of usability of the structures in fire conditions, according to Eurocodes and the standards in force.

PYROLYSIS MODELING OF PVC USING DISTRIBUTED ACTIVATION ENERGY MODEL- MICRO SCALE TESTING

Abhishek Bhargava — 2016-01-18

Polyvinyl chloride (PVC) is a common thermoplastic whichfinds widespread applications in the construction industryfor usage inceiling linings, flooring materials, electrical cables and roofing materials.Several fire requirements are put on these types of applications. For fire safety engineering and product development, thermo-chemical decomposition modeling of PVC isrequired. The FIRETOOLS project investigates the possibilities to predict real scale fire behavior of building products, content and barriers by means of using material data on successively increasing scale. This paper focuses on the material modeling and studiesthe thermo-chemical decomposition of PVC using Distributed Activation Energy Model (DAEM).

CAPACITY BUILDING IN HIGHER EDUCATION, Resilience improvement in Balkan region

Mirjana Laban — 2016-01-18

In order to improve the resilience of the region to hazards, it is necessary to provide the required number of experts that is to modernize and develop higher education at the regional higher education institutions in the field of Disaster Risk Management and Fire Safety Engineering. A master study program should be developed to satisfy various criteria, according to regional needs for resilient society, such as the shift from reactive to proactive actions, developing a culture of prevention in built environment and learning to live with risks. Final goal is to produce capable experts, to be able to withstand difficult requirements of today and tomorrow. Compliance of the regional master program with similar programs, developed in the EU countries, strengthens the capacity of individual countries and the region as a whole in the process of European integration.

FIRE RESISTANCE GLAZED CONSTRUCTIONS CLASSIFICATION, Changes in the field of application

Jacek Kinowski — 2016-01-18

The most common fire resistance glazed constructions are arguably doors and non – loadbearing walls (partitions, curtain walls, external walls). In 2014 we welcomed revisions of fire resistance testing standards for doors (EN 1634-1) and curtain walls (EN-1364-3), while revision of EN 1364-1 standard for non – loadbearing walls is planned to be implemented by the end of the year 2015. Taking into account the existence of several EXAP’s for all these kind of constructions, selection of test specimen(s) with best possible configuration is getting more significant nowadays. But equally important question appears - how to treat previously performed fire resistance tests?

This paper discusses some interpretation concerns regarding fire resistance classifications of aluminium glazed, non – loadbearing constructions in light of rapidly changing regulations. The paper also points out same examples of testing evidence with regard to outlined concerns.

IMPROVING THE QUALITY OF FIRE RISK ASSESSMENT BY USING EVACUATION SIMULATION SOFTWARE

Srđan Popov — 2016-01-18

The time required for evacuation of all persons who could be present in the building during a fire event depends on a number of factors, some of which are very difficult to predict. In order to achieve more realistic evaluation of the evacuation process, engineers are increasingly turning towards evacuation computer models. These evacuation models could help reduce the consequences related to a wide range of adverse events, such as fires, by indicating critical points on the evacuation paths. At the same time, simulation tools can be used for exploring how certain changes within the real system could affect the efficiency of evacuation and fire safety of the building even before they are implemented. The computer model for the Amphitheatres in FTS in Novi Sad has been created using simulation software – Pathfinder, based on SRPS TP 21. This paper presents contribution of evacuation software models to the quality of fire safety assessment.

FIRE RESISTANCE TESTS OF ALUMINIUM GLAZED PARTITIONS, Results comparison

Bartłomiej Sędłak — 2016-01-18

This paper discusses the main problems related to the fire resistance of aluminium glazed partitions, including the tests methodology and way of classification of this type of elements. Moreover, the paper presents the comparison of fire resistance test results of glazed partition test specimens, depending on the number of insulation inserts placed inside the aluminium structure profiles. To made the comparison the specimens with the same transom – mullion structure were tested in two configurations and with two filling solutions – with profiles filled only in the middle part and with fully filled profiles.

FIRE RESISTANCE OF ALUMINIUM GLAZED CURTAIN WALLS, Test results comparison depending on the side of fire exposure

Paweł Sulik — 2016-01-18

This paper discusses the main issues related to the fire resistance of aluminium glazed curtain walls including the tests methodology and way of classification of this type of building elements. Moreover, the paper presents the comparison of fire resistance test results of large test specimens of curtain walls in full configuration depending on the side of fire exposure. Temperature rises have been compared on unexposed surface of the curtain walls tested for standard and external fire exposure. To made the comparison four test specimens of glazed aluminium curtain walls in full configuration, were tested. Curtain walls had the same transom – mullion structure. Two test specimens were tested for external fire exposure, and two for standard fire exposure. Dimensions of exposed surfaces were 5000 x 4500 mm (width x height) for external fire exposure and 5000 x 4800 mm (width x height) for internal fire exposure.

THERMAL INSULATION OF SINGLE LEAF FIRE DOORS, Test results comparison in standard temperature-time fire scenario for different types of doorsets

Daniel Izydorczyk — 2016-01-18

Fire resistant door assemblies (doors) for pedestrian or industrial traffic with frame, leaf or leaves, rolled or folded curtain etc. are designed for installation in the openings of the building’s vertical internal partitions. The building and its associated equipment shall be designed and made so that in case of fire it ensures the necessary load bearing capacity of the structure for the time specified in national regulations, limitation of fire and smoke propagation within the building, limitation of fire propagation onto the adjacent buildings and evacuation of people, and it provides safety of the rescue teams. The mentioned requirements are not usually considered individually (e.g. ensuring proper evacuation is connected with the structural load bearing capacity, fire and smoke propagation within the building, and rescue team safety), therefore individual elements of buildings can play several roles during a fire.

This also refers to the building elements such as doors which are usually required in terms of design and execution to ensure that in case of fire they shall, for a specific period of time prevent its development from the room or a specific zone where the fire started to other rooms or zones, allow evacuation of people by limiting heat radiation, and facilitate rescue team activities. Therefore, fire doors have a major role in the fulfillment of the rules of buildings fire safety.

This paper discusses the main issues related to the fire resistance of fire doors (tests methodology and way of classification) and presents a comparison of temperature rises on unexposed surface of fire doors test specimens depending on the type of structure and side of fire exposure. Temperature rises have been compared on unexposed surface of timber, aluminum and steel single leaf doorset which have fulfill the requirements of the EI₂ 30 fire resistance class, in case of the fire acting from the hinge side and the side opposite to the hinges.

CONTRIBUTION OF SOCIAL PSYCHOLOGY FOR UNDERSTANDING OF HUMAN BEHAVIOR DURING FIRE EMERGENCY

Miljenko Antić — 2016-01-18

Today we have plenty of evidence about people’s reaction in the case of fire. Some reactions are peculiar for the fire emergency. However – in order to understand these reactions – it is important to know the basic principles of individual and group behavior. The main goal of this article is to present results of psychological investigations of basic instincts (anxiety, fear, panic) and results of investigations of group behavior (social facilitation, conformity, altruism, diffusion of responsibility, respect for authority, etc.) and to apply these results on investigation of human behavior during the fire emergency. In short, this article has aim to explain human behavior during the fire emergencies on the basis of main findings of social psychology. Furthermore, the article suggests possible activities – especially in the field of education and training – that may decrease human loses in fires.