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In the past decades, increasing attention has been directed to understanding the structural response to various scenario fires, which is stimulated by the trend of considering localised burning in large open plan compartments. Beam-column elements as widely used in modelling steel frames have been extended to account for the thermal impact in OpenSees, the development of which is undertaken to formulate the displacement and force-based beam elements. After including the non-uniform thermal expansion along the element length caused by localised heating, the force-based beam-column element has shown greater efficiency compared to the displacement-based element. A detailed discussion regarding the computational performance of both beam-column elements has been presented in this paper, which concludes that force-based beam-column elements can better represent the localised plasticity of fibres caused by non-uniform heating. A generic simply supported steel beam can be modelled even with two force-based elements to reproduce accurate mid-span deflection under localised heating. A steel beam subjected to a localised fire is presented as a case study in this paper, experiencing run-away collapse after 15 min of exposure when the load ratio reaches 50%. Using a 12 element force-based beam-column model and shows equivalent accuracy against 48 element displacement-based beam-column model. [ABSTRACT FROM AUTHOR]

• Modelling and characterisation of fire-spotting generated fires. • Study the effects of the atmospheric stability conditions on the behaviour of fire-spotting generated fires. • During stable conditions, there are many active fires because turbulent heat transport does not merge them rapidly. • During unstable conditions, the formation of unburned islands surrounded by the fire are observed. • Different atmospheric stability conditions cause different risks requiring different management. This is the first part of two papers concerning fire-spotting generated fires. In this part we deal with the impact of macroscale factors, such as the atmospheric stability, and in the second part we deal with mesoscale factors, such as the flame geometry. For this study we adopt an approach where the motion of the front is split into a drifting part and a fluctuating part. The drifting part, that can be provided by choosing an existing operational model, is here based on the level-set method in analogy with WRF-SFIRE model. The fluctuating part, that is the result of a comprehensive statistical description of the physics of the system and includes the random effects, is here physically parametrized to include turbulent hot-air transport and firebrand landing distance. In order to highlight the net effects of the random contributions due to turbulence and firebrand flying, a simplified model without fire-atmosphere coupling is considered. Numerical simulations show that the atmospheric stability is an important factor for wildfire propagation. In particular, unstable conditions boost the number of fire-spotting generated fires at small elapsed times as well as the strength of turbulence leading to rapid merging and the formation of unburned islands surrounded by the fire. Stability conditions have then an effect on the risk and the management associated to fire-spotting generated fires. In fact, with stable conditions (corresponding for example to the night-time) the turbulence is not strong enough to merge the fires and, at large elapsed times, this results into a higher number of independent fires but lower burned area with respect to unstable conditions (corresponding for example to the day-time) when the push of turbulence leads to faster merging resulting into a lower number of independent fires but higher burned area. Finally, with stable conditions less fire fronts need to be managed at short time, but more fire fronts need to be managed than with unstable conditions that however show a higher risk because of the merging of independent fires. [ABSTRACT FROM AUTHOR]

A series of experiments were carried out to investigate the effect of ullage height, i.e. the distance between fuel surface and the pool upper rim, on flame characteristics of heptane and ethanol pool fires. The pool diameters included 10 cm, 15 cm, and 20 cm. For each pool, ullage height was increased from zero to the value that the flame self-extinguished. During each test, the ullage height was kept constant by a fuel level maintaining device. Results show that ullage height has a significant effect on flame characteristics. When the ullage height equals zero, there is a stable conical structure near the pool upper rim, above which the unstable plume develops. Under lower ullage height conditions, plume puffing happens. The unstable plume begins to initiate around the pool upper rim, then rolling and expanding upward. At the same time, its beneath flame is stretched thinner and thinner and eventually breaks from the bulk. When the ullage height further increases, plume puffing becomes less evident. While for the mass loss rate, it generally decreases with the increase of h / D. It was proved in literature that the previous flame height model is inapplicable to pool fires with large ullage height. In this paper, to consider the effect of ullage height on plume flow structures, an equivalent hydraulic diameter, D eq. , is proposed to establish one new flame height correlation. By comparing previous model predictions with the current experimental data, it is found that conventional flame oscillation models are unsuitable to pool fires with large ullage height. Based on D eq. , two new dimensional and dimensionless flame oscillation models were proposed according to the current experimental data. The correlated flame height model and proposed flame oscillation models were validated and agreed well with reference data. [ABSTRACT FROM AUTHOR]

The interaction between jet flame and vortex flow is a fundamental combustion phenomenon which could occur in actual fire accidents. This paper presents a systematical investigation on such jet fire in a rotating flow field (JFRFF). A new facility was designed for the experimental study, which consists of a jet fire apparatus and a whirl generator. The test repeatability was justified for the proposed facility. The dynamical differences of JFRFF, free jet fire and fire whirl are clarified. A set of correlations are proposed for the flow circulation, flame height, lift-off height and frequency of flame wander of JFRFF. The flow circulation is found to well couple the inlet velocity and the flow guide angle as Γ = 0.80 π D d u a sin θ. The results have also shown that the JFRFF has a larger flame height than the free jet fire in still air, while the lift-off height is shorter than the free jet fire. Theoretical analysis identifies two competitive effects of flow circulation on the flame height of JFRFF. The enhancement of air entrainment in the ground layer reduces the flame height by decreasing the jet momentum, whereas the reduction of fuel-air mixing rate in the upper flame increases the flame height. The flow circulation reduces the vertical velocity of gas mixtures in the ground boundary layer, resulting in a less lift-off height. However, similarly as for fire whirls, the flame of JFRFF wanders as whole with the centerline being not completely perpendicular to the horizontal plane, and the appearance probability of flame fits Gauss distribution. It is also found that the frequency of flame wander can be positively correlated to the tangential component of inlet velocity. [ABSTRACT FROM AUTHOR]

• Fire exposure influences the behaviour of RC connections during collapse. • Variation of reinforcement detailing at beam end influences collapse response of RC connections. • The simplified model accounts for the combined loading states due to axial restraint and fire. • Practical considerations are highlighted to improve the rotational capacity. This paper examines the behaviour of RC beam-column joints with different reinforcement detailing arrangements under pushdown loading before and after fires. The thermal responses of the RC joint specimens are firstly described, including the development of the temperature fields and the horizontal reactions as well as the deflections during the heating and cooling phases. Subsequently, displacement-controlled push-down tests are performed, and the vertical load, horizontal reactions as well as detailed deformations are monitored. The bending moment-rotation relationships are derived from the test results, together with an account of the observed failure modes. The mechanical behaviour is also discussed in detail, including the rotational capacity, with emphasis on the effect of different reinforcement detailing arrangements as well as the post-fire condition. Particular attention is given to comparing the experimental axial-moment strength interaction curves and theoretical predictions under ambient conditions so as to examine the underlying mechanisms. In order to support practical application, a simplified analytical method is proposed for simulating the push-down response, based on the combined loading states and idealised constitutive relations, taking into consideration the restraint effect due to horizontal restraint or fire conditions. The suggested analytical procedure is shown to be a reliable and effective approach for representing the behaviour. Based on the findings of this investigation, practical considerations for enhancing the rotational capacity of RC joints are highlighted. [ABSTRACT FROM AUTHOR]

Abstract This paper investigates building eave effect of fire-induced ejected plume from a room window and its heat flux imposing upon the facade wall. Based on a 1:8 cubic model and Froude modeling, a series of reduced scale experiments are set up. The window dimensions and total heat release rate due to a room fire are changed during experiments. The eave upon the facade wall, made of noncombustible fiber board is installed horizontally above the window top, varying with different vertical heights (distance of the eave to the window top) and lengths (direction normal to the facade wall). The facade flame height is recorded by a CCD camera, while the heat fluxes imposing upon the facade wall are collected by five water-cooled heat flux gauges. Results show that the ejected flame with horizontal eave can be distinguished into the "free flame stage", the "flame horizontal spread stage" and the "flame overflow stage". The visible flame height and heat flux within the "flame overflow stage" are detailed discussed, revealing the physical mechanism of the vertical height and length of the horizontal eave effects. Finally, an implicit correlation in regarding with the visible flame height, the updated flame extension area beneath the horizontal eave as well as the vertical height of the horizontal eave to the window top is established. Taking the horizontal eave conditions into consideration, the heat flux correlation is well corrected and proposed. The results would provide theoretical basis for the fire-induced thermal protection in high buildings. [ABSTRACT FROM AUTHOR]

Abstract The accidental leakages of combustible fuel during storage and transportation cause the pool fires which impose hazardous heat on the nearby occupants and facilities mainly by thermal radiation. This paper presents a new semi-empirical radiation model, namely, the multi-layer cylindrical flame model to predict the radiant heat flux field of pool fires. As the centerline temperature of pool fire varies significantly with vertical height, a formula is proposed to characterize the vertical profile of flame surface emissive power with which the new model can predict the radiant heat flux. The reasonable layer number (the number of small cylinders used for model prediction) can be determined using sensitivity analysis. Comparisons with the experimental data of methanol, heptane, toluene and propane pool fires of different pool diameters indicate that the new radiation model can give a good prediction on the thermal radiation in both horizontal and vertical directions, in spite of fuel type and pool diameter. In comparison with the point source model and three typically single cylindrical flame models, the new radiation model seems to give encouraging results relative to the validity of model system. Sensitivity analysis is also conducted to rank the importance of model parameters. [ABSTRACT FROM AUTHOR]

Abstract Previous studies have usually focused on an ordinary single tunnel fire. However, the structural effect of metro connected tunnel area on the smoke temperature still needs to be clarified. Therefore, this paper aims to modify the current model for predicting the fire-induced smoke temperature considering different sloped conditions in main and connected tunnels. Small-scale and full-scale experiments were conducted with the main tunnel and connected tunnel being horizontal, then extended numerical simulations were performed to clarify the common inclined effect of both the main and connected tunnel on the smoke temperature under natural ventilation. The results show that, maximum smoke temperature varies with a reduction or enhancement of the heat accumulation caused by slope conditions in both the main and connected tunnels. The dimensionless temperature profiles along the smoke spread depends on the slopes of current tunnel itself and are affected little by slopes of another connected one. Prediction models for the maximum smoke temperature and longitudinal temperature profiles were further developed by taking the main and connected tunnel slopes into account. Moreover, it performs good fitting degree for the correlated temperature profile and the predicted maximum smoke temperature agree well with experimental and simulated results, which provides an easy-to-use method for estimating smoke temperature in a fire prevention design or emergency rescue in such metro system. Highlights • Reduced-scale, full-scale experiments and numerical simulations are carried out. • Smoke temperature beneath ceiling in metro tunnel connected area is studied. • Effect of both the main and connected tunnel slopes on smoke temperature is analyzed. • Modified prediction model for smoke temperature in metro connected tunnel area is proposed. • The correlations show good fitting degree and well validated with experiments and simulations. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a coupled fire-structure model combining the finite volume and finite element methods, which captures the essential physics of the problem has been developed. The model is based on a multi-physics framework where the essential physics pertaining to the combustion process of the fire and resultant thermo-mechanical response of the structure, in particular, of natural fibre reinforced composites, has been incorporated. In addition, a relatively new concept of adiabatic surface temperature has been introduced as a practical means to transfer data between fire and thermal/structural models at the gas-solid interface. The model predicts the temperature, stress distribution and deformation behaviour of composite beams under combined thermal and mechanical loads. [ABSTRACT FROM AUTHOR]

Abstract In this paper, comprehensive experimental and numerical analyses are carried out to compare the fire reaction properties of wool and flax based polypropylene composites under horizontal and vertical orientations. Moreover, extensive numerical analysis results on the fire reaction properties, burn time and surface temperature distribution have been reported. Fire Dynamics Simulator (FDS®) was employed to develop a numerical predictive model for the cone calorimeter. The study revealed that vertical samples ignited later compared to the horizontal ones. In addition, it has been shown that fibre type has a significant effect on the heat release rate in horizontal and vertical tests. The surface temperature distributions showed similar trends for both composites. [ABSTRACT FROM AUTHOR]

Beams with web openings represent an attractive system for multi-storey buildings characterized by long spans. Openings in web of steel beams enable building services to be integrated within the constructional depth of the floor, thus reducing the total floor depth. This paper employs the general finite element software ABAQUS to numerically model the behaviour of restrained structural subassemblies of steel beam with web openings to concrete filled tubular column under fire loading scenarios. Steel beams, in this case, are axially restrained which results in a drastically different behaviour when compared to unrestrained beams. In this research, a comprehensive finite element (FE) study of the behaviour of structural subassemblies of steel beams with openings under fire scenarios is conducted. Four sizes of perforated steel sections with seven different opening configurations are modelled and studied in order to understand the significance of their effects. Moreover, the influence of applied load ratios in addition to the level of axial restraint are examined. Consequently, considerations for the performance of axially restrained perforated steel beams under fire scenarios is provided. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation on residual mechanical properties of high strength steels (HSS) after exposure to fire. A test program was conducted to study the post-fire mechanical properties of cold-formed HSS. A total of 41 tensile coupon specimens was extracted from cold-formed tubular sections with nominal yield stresses of 700 and 900 MPa. The specimens were exposed to various elevated temperatures ranged from 200 to 1000 °C and then cooled down to ambient temperature before testing. Stress-strain curves were obtained and the mechanical properties of Young's modulus, yield stress (0.2% proof stress), ultimate strength, ultimate strain and fracture strain of the cold-formed high strength steel materials after exposure to elevated temperatures were derived. The post-fire retention factors that obtained from the tests were compared with existing predictive equations in the literature. The influence of heating rate on post-fire mechanical properties was also investigated. New predictive curves for the determination of residual mechanical properties of HSS after exposure to fire are proposed. It is demonstrated that the proposed predictive curves are suitable for both cold-formed and hot-rolled HSS with nominal yield stresses ranged from 690 to 960 MPa. [ABSTRACT FROM AUTHOR]

Following the present directives for building products, the manufacturers of intumescent paints for fire protection of structural steel typically offer tables for presentation of the product's insulating efficiency showing its dry film thicknesses (DFTs) required to sufficiently delay the defined steel critical temperature. From these tables only the final time of reaching this critical limit is obtained clearly, but the overall time evolution of steel temperature remains unknown. In connection to EC3, these data are only sufficient for the use of a simplified design procedure, mostly the method of critical temperature (MCT). Although of a questionable adequacy for cases of restrained thermal dilatations this method is, thus, often applied regardless of the specifics of the structural assembly. The severity of the error implemented by such a simplification is taken as the principal focus of the paper. In providing an answer, fire test results are presented for 13 different steel members protected by different DFTs of a selected intumescent coating. Then, the time-dependent thermal conductivity of the coating is derived and numerical procedure is composed for obtaining the real fire response of intumescent painted assemblies. The method is implemented into a parametric study. The calculated critical times are compared against the critical times suggested by the MCT revealing the MCT being severely on the unsafe side for some cases. The paper thereby confirms the initial hypothesis that the present way of presenting the fire-protective intumescent paints for structural steel is insufficient and will need to be upgraded in the future. [ABSTRACT FROM AUTHOR]

A potential but infrequently studied hazard is the sequential occurrence of earthquakes and fires. Fire hazards following an earthquake can be significant due to increased likelihood of fires igniting, increased demands on firefighting resources, and potential obstacles to timely response. Increased ignitions and longer burn times can have significant structural impacts on reinforced concrete (RC) structures which are usually considered to have superior performance in a fire. The impact of this fire induced structural damage on the lateral load resistance of RC structures, particularly RC structural walls, is not well understood but may be critical in the event of aftershocks and/or future earthquakes. Given the severity of the consequences of reduced lateral load resistance, it is important for engineers to better understand fire-earthquake hazards in RC walls. This paper presents numerical studies to investigate the impact of fire damage on the lateral load resistance of flexure-controlled RC structural walls, including a parametric study to identify influential wall characteristics. Results indicate that fire damage decreases the load-bearing capacity and the stiffness of RC walls under reversed-cyclic loads. Curvature is shown to be a better indication of fire induced failure. At failure, damage may shift to the web of a wall after fire exposure becomes more severe. Wall characteristics which significantly influence the residual wall response quantities were identified to be wall thickness, boundary element length, and axial load ratio. [ABSTRACT FROM AUTHOR]

Sealing smothering method is an important approach to control large fire in channels. This paper experimentally studied the fire behaviors after the sealing in a reduced-scale channel model, considering different initial sealing time under different sealing rates. A series of characteristic parameters, such as the temperature over fire source, mass loss rate of fuel, CO concentration at channel entrance as well as smoke temperature at channel entrance were measured. The results showed that for complete sealing, the earlier the initial sealing time is, the better the fire can be suppressed with a shorter burning duration and lower temperature. However, for incomplete sealing, although the sealing implemented before violent burning stage can reduce the temperature effectively, it causes a much longer burning duration and induces a higher CO concentration at the channel entrance. Especially during violent burning stage, the sealing not only does not restrict fire growth but also exacerbates the channel fire with an extremely high CO concentration at the channel entrance and a longer ceiling flame jet. Besides, as long as one of the channel entrances is not sealed completely, the temperature above the ceiling at channel entrance increases immediately after the sealing, which should be noticed for firefighters during fire rescue. [ABSTRACT FROM AUTHOR]

Archival research into episodes of frontier violence in the Kimberley region of Western Australia indicate that the bodies of Aboriginal victims of massacres were frequently incinerated following the event. This paper presents the results of a scientific investigation of a reported massacre at Sturt Creek where burnt bone fragments were identified in two adjacent sites and documents the archaeological signatures associated with the sites. The methodology used to undertake the project brought together three systems of knowledge: the oral testimonies of the descent group originating from a sole adult survivor of the massacre; archival, historical and scientific research. An archaeological survey defined the two distinct sites containing hundreds of fragile bone fragments; a third site was found to be highly disturbed. Scientific investigations included macroscopic and microscopic examination of selected bone fragments by an anatomical pathologist and a zooarchaeologist and X-ray diffraction analysis of sixteen bone fragments. The anatomical pathologist and zooarchaeologist undertook macroscopic and microscopic examinations of selected bone samples to identify morphological evidence for human origin. It was concluded that three bone fragments examined may have been human, and two of the fragments may have been from the vault of a skull. It was concluded that the likelihood of them being human would be strengthened if it was found that the three samples had been subjected to high temperatures. X-ray diffraction analysis of 16 bone fragments provided this evidence. All fragments showed sharp hydroxylapatite peaks (crystallite sizes 9882nm and 597nm respectively) and all had been subjected to extreme temperatures of either 600°C for more than 80h, 650°C for more than 20h, 700°C for more than 4h or 800°C for more than 1h. XRD analyses were also done on bone samples collected from three cooking hearths at three different archaeological sites. It was found that two of the three samples had been exposed to substantially lower temperatures for a short time period. It was concluded that there was strong pathological and archaeological evidence that the bone fragments were human in origin, but that the evidence was not conclusive. This research also identified archaeological signatures for the identification of massacre sites in similar Australian environments and circumstances. [ABSTRACT FROM AUTHOR]

This paper summarizes the small scale thermal exposure test results of the performance of metallic and polymeric O-ring seals typically used in radioactive material transportation packages. Five different O-ring materials were evaluated: Inconel/silver, ethylene-propylene diene monomer (EPDM), polytetrafluoroethylene (PTFE), silicone, butyl, and Viton. The overall objective of this study is to provide test data and insights to the performance of these O-ring seals when exposed to beyond-design-basis temperature conditions due to a severe fire. Tests were conducted using a small-scale stainless steel pressure vessel pressurized with helium to 2 bar or 5 bar at room temperature. The vessel was then heated in an electric furnace to temperatures up to 900 °C for a pre-determined period (typically 8 h–9 h). The pressure drop technique was used to determine if leakage occurred during thermal exposure. Out of a total of 46 tests performed, leakage (loss of vessel pressure) was detected in 13 tests. [ABSTRACT FROM AUTHOR]

Savannas are dynamical systems where grasses and trees can either dominate or coexist. Fires are known to be central in the functioning of the savanna biome although their characteristics are expected to vary along the rainfall gradients as observed in Sub-Saharan Africa. In this paper, we model the tree–grass dynamics using impulsive differential equations that consider fires as discrete events. This framework allows us to carry out a comprehensive qualitative mathematical analysis that revealed more diverse possible outcomes than the analogous continuous model. We investigated local and global properties of the equilibria and we showed that various states exist for the physiognomy of vegetation. Though several shifts between vegetation states appeared to be determined by fire periodicity, we showed that direct shading of grasses by trees is also an influential process embodied in the model by a competition parameter leading to bifurcations. Relying on a suitable nonstandard simulation scheme, we carried out numerical simulations in reference to three main climatic zones as observable in Central Africa. [ABSTRACT FROM AUTHOR]

In this paper a simplified analytical method to assess the ductility demand on connections according to fire resistance requirements is developed on the basis of fundamental structural mechanics principles. An objective is to enable the development of a viable method to allow engineers to take the ductility of connections into account in design practice. Numerical finite element simulations of the single beam model were also performed to validate the simplified analytical model and reveal the important parameters that can influence the ductility demand within the connections. Using both analytical and numerical methods, the principal factors which influence the ductility demand of a connection, such as the span of the connected beam and the required connection strength, are also assessed. It is shown that: 1. The compressive ductility of connections is helpful in reducing the push-out of perimeter columns and the possibility of local buckling of beams. 2. Provision of high tensile deformation capacity allows large deflection in the beam, substantially reduces catenary forces on the connections, and consequently reduces the risk of structural collapse in fire. 3. The ductility demand of the connection is closely related to its stiffness and strength, as well as to the slenderness and load ratio of the connected beam. [ABSTRACT FROM AUTHOR]

This paper investigates the fire performance of highly utilized and eccentrically loaded concrete filled composite columns with slendernesses greater than currently permitted by the simple calculation model in Eurocode 4 Part 1.2. The fire resistance rating was calculated by applying implicit as well as explicit finite element analyses and undertaking sequentially coupled thermal-stress analyses. Initially, published fire tests on concentrically loaded columns as well as columns with a modest load eccentrically ( e / h ≤ 0.25) were analysed with normal (NSC) and high strength concrete (HSC). Following the validation of the numerical model against the test data, a parametric study was undertaken on a composite column using a 400 mm square hollow section with a fixed-pinned boundary condition and a relative slenderness at room temperature of λ ̅ = 0.6 . Load levels η fi,t of 0.47, 0.35 and 0.24 were considered and, using a constant eccentricity of e / h = 0.5, a combination of concentric and eccentric loading was applied to the column, as would occur in practice. The results from the parametric analyses show that the FRR reduces significantly as the bending moment increases on the column. Moreover, although the FRR reduced as the utilization increased, it was found that for highly utilized columns the FRR was less sensitive to changes in the magnitude of the bending moments. [ABSTRACT FROM AUTHOR]

This paper presents an approach for assessing the residual capacity of fire exposed reinforced concrete (RC) beams. The approach involves capturing response of RC beams in three stages, namely, structural response at ambient conditions, thermo-mechanical response during fire exposure, and post-fire residual response after cooling down of beams. Distinct material properties of reinforcing steel and concrete are considered during heating and cooling phase of fire exposure and residual (after cool down) phase of analysis. In addition, relevant load level, specific fire scenarios, boundary conditions, and plastic deformations that develop in a beam during fire exposure are also incorporated in evaluating residual response of fire exposed RC beams. The proposed approach is implemented using a detailed numerical model developed in the finite element computer program ABAQUS. Predictions from the numerical model show good correlation with the response parameters measured in experiments for evaluating residual capacity of fire exposed RC beams. Also, predictions of residual capacity from the finite element analysis are compared with that obtained from simplified sectional analysis based on maximum rebar temperatures consideration. This comparison indicates that the finite element analysis yields more realistic predictions of residual capacity than that predicted from simplified sectional analysis. The applicability of the proposed approach in evaluating residual capacity of fire exposed RC beams is illustrated through a case study. [ABSTRACT FROM AUTHOR]

Since the Vreman subgrid-scale model was proposed, different types of flow fields have been used to research the applicability of this model. However, the applicability of the model to a flashover heat flow field simulation and the optimal model coefficient for room fires have not been reported. In this paper, the flashover room fire experiments of different opening sizes (ventilation factor) are conducted in an experimental room of size similar to ISO9705, and the room temperature at typical locations is measured. On the same numerical simulation platform, the room temperature field is simulated numerically using the large eddy simulation based on the Vreman and Smagorinsky subgrid-scale models. When the ventilation factors are 1.932 and 2.178, a Vreman subgrid coefficient of 0.02–0.04 is more applicable to the simulation of the temperature field. Overall, the simulation results of the maximum temperature based on the Vreman subgrid-scale model are slightly better than that of Smagorinsky subgrid-scale model. Moreover, the simulation result of the temperature change according to the time from the Vreman subgrid-scale model is similar to the experimental result. However, near the corner of the door in the room, the numerical simulation results underestimate the maximum flow field temperature in the room’s upper part. When the Vreman subgrid-scale model simulates the temperature field in the room with a subgrid coefficient of 0.04 and a ventilation factor of 2.263, the simulation results are better than the results from the Smagorinsky subgrid-scale model with a subgrid coefficient of 0.2. However, when the ventilation factor is 1.397 and the opening is relatively small, the large eddy simulation result based on the Vreman subgrid-scale model with a subgrid coefficient of 0.04 is worse than the results based on the Smagorinsky subgrid-scale model with a subgrid coefficient of 0.2. [ABSTRACT FROM AUTHOR]

This paper demonstrates the need for structural fire engineering in the design and specification of unusual structural arrangements. It is found that the required fire resistance of a structure cannot necessarily be achieved by considering only the fire resistance of individual elements of structure. A case study of columns that have a change of direction over their height (geometrically bi-linear columns) is used to illustrate how unusual arrangements may lead to early failure of key structural elements – even where design guidance is followed. These arrangements are parameterised to allow the relative importance of a number of key variables to be studied. A methodology is developed to estimate the required limiting temperature for the governing elements of the assembly in order to deliver the required performance. [ABSTRACT FROM AUTHOR]

Concrete filled steel hollow structural (CFS) sections are an increasingly popular means to support large compressive loads in buildings. Whilst the response of unprotected CFS sections during a fire is reasonably well researched, their post-fire residual structural performance is less well established. A better understanding of the response of fire-damaged CFS columns is needed to enable better performance-based structural fire engineering of buildings incorporating CFS sections. This paper presents post-fire residual compression tests on unprotected and protected CFS columns along with control tests on six unheated sections. The tests confirm that as the maximum exposed temperature within the cross-section increases, the residual strength capacity, ductility and axial–flexural stiffness decrease. The data are subsequently used to assess the ability to predict the residual capacity of CFS columns after fires, using available post-fire material models and in-fire and ambient structural models. [ABSTRACT FROM AUTHOR]

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

In the corridors, combustion products of the fire are confined to spread in one or two directions, forming a ceiling-jet flow. For safety assessment and emergency treatment, it is important to investigate and understand the behavior of the ceiling-jet flow. In this paper, a simplified model has been developed and improved, which has been verified by the numerical calculation. It is worth mentioning that for the radial spreading region, we have simplified Alpert’s equations, and obtained the simplified solution. Moreover, in this region, the mass entrainment has been got by linear fitting. And for the region of hydraulic jump, two sub regions of IV1 and IV2 have been established to analyze the conversion process. In order to validate the theoretical predictions, a series of small-scale experiments and numerical simulations have been conducted to validate the physical model of corridor fires. The predicted results, concerning exit position and flow state in near field, agree favorably with experimental data in different conditions. [ABSTRACT FROM AUTHOR]

Steel short columns are used in building structures. The heating conditions in real building fires are non-uniform. The structural fire design approaches in the Eurocode are based on uniform heating conditions. This paper presents a numerical investigation on the behavior of steel short columns subjected to a localized fire. The effect of non-uniform heating condition on the failure temperature of axially loaded steel short columns is studied. Failure temperature is defined here as the maximum temperature in a steel column at failure (e.g. the onset of buckling or squashing). Simple thermal models were used to calculate the temperature of steel short columns in localized fire conditions. Sequentially coupled thermal–mechanical simulations were conducted. The study finds that the failure temperature of steel short columns in a localized fire is much higher than that of columns with a uniform temperature. The failure temperature in a localized fire might be slightly lower (within 20 °C) than that in the standard ISO 834 fire. The Eurocode design equations give conservative results of the failure temperature for steel short columns subjected to localized fires. [ABSTRACT FROM AUTHOR]

Underground mine fire disasters are one of the major types of disasters that occur in the mining industry. This paper examines a method for simulating underground fire disasters based on Cellular Automata. Cells are used to describe the mass energy units produced in underground mine fires. The combustible and combustion status, the physical and life attributes, and the rules of the fire cells evolution were described. An underground fire source ignition model that highlights the expression of cell temperature was established from an analysis of factors including the types and throw-in density of combustible matters, the underground ventilation system and the slope of the tunnels. An underground fire fume spread model that focused on illustrating cell density was then created from an analysis of factors including the double diffusion effect, underground ventilation, buoyancy function, and throttle action. On this basis, the status and attributes of fire cells were described according to a sequence of time by means of visualization. This model intuitively describes the spatial–temporal development process of the fire source ignition and smoke spread in an underground mine fire disaster. The feasibility of the Cellar Automata model for underground mine fire disasters, and its visualization effects were tested and verified through a case study. [ABSTRACT FROM AUTHOR]

This paper describes the mechanical behavior of wire ropes under fire conditions with the aim of developing a method for determining the fire resistance of steel wire ropes for civil and ropeway applications. The behavior of ropes subjected to severe thermal transients representative of fire scenarios has been investigated through numerical and experimental analyses. Since no standards are available for studying the fire behavior of these structural elements, the ISO 834 standard curve was considered as fire model owing to its severity. For this purpose, parametric finite element models, capable of simulating the thermo-mechanical response of both full locked and Warrington Seale ropes have been developed. The obtained information in terms of load redistribution during the test as well as evolution of damage and failure mechanisms was used to set up the experimental investigation. The good agreement between experimental and numerical results indicates the proposed approach as an effective methodology for the analysis of the fire behavior of wire ropes, once the material properties and loading conditions have been established. [ABSTRACT FROM AUTHOR]

Recent experimental tests and numerical simulations about the fire resistance behaviour of CFRP-strengthened RC beams proved that CFRP strengthening systems are able to attain considerable fire endurance, provided that adequate fire protection systems are used. In a fire event, even though a CFRP laminate may rapidly debond from the central part of the beam in which it is installed, if sufficiently thick insulation is applied in the anchorage zones, the laminate transforms into a "cable" fixed at the extremities, thus maintaining a considerable contribution to the mechanical response of the strengthened beam. This paper presents experimental and numerical investigations on CFRP-strengthened RC beams with the objective of understanding in further depth their fire resistance behaviour, namely the influence of the above mentioned "cable" mechanism on the mechanical response of the beams. The experimental campaign, performed at ambient temperature, comprised 4-point bending tests on RC beams strengthened with CFRP laminates according to either the EBR or the NSM techniques, in both cases fully or partially (only at the anchorages, thus simulating the cable mechanism) bonded to the soffit of the beams. For the test conditions used in this study, for both types of strengthening systems, partially bonding the CFRP laminates did not affect the stiffness of the beams and caused only a slight reduction of their strength (6-15%). The numerical study comprised the simulation of the structural response of all beams tested. Non-linear finite element models were developed in Atena commercial package, in which a smeared cracked model was adopted to simulate concrete and appropriate bond-slip constitutive relations were defined for the CFRP-concrete interfaces. A very good agreement was obtained between experimental data and numerical results, providing further validation to the "cable" mechanism and the possibility of taking it into account when designing fire protection systems for CFRP-strengthened RC beams. [ABSTRACT FROM AUTHOR]

Abstract: This paper investigates experimentally the side wall constraint effect on facade flame behavior ejected from the opening of an under-ventilated compartment fire. Experiments are carried out in a reduced-scale experimental model of 1:8, consisting of a cubic fire compartment (including one opening) with a vertical facade wall and two side walls. The facade flame heights for different opening geometries (width, height) are recorded by a CCD camera under various side wall separation distances. It is found that as the distance of the two side walls decreases, the change of the flame height can be categorized into two regimes, due to correspondingly the two different facade flame entrainment behaviors distinguished by the dimensionless excess heat release rate , outside the opening: (a) for the “wall fire” ( ⩽1.3), the flame height is shown to change little with decrease of side wall distance as the dominant entrainment is from the front direction (normal to the facade wall) irrelevant to the side wall distances; (b) for the “axis-symmetrical fire” ( >1.3), flame height increases prominently with decrease in side wall distance as both the entrainment from two side directions (parallel to the facade wall) and that from the front direction (normal to the facade wall) together dominate. A global non-dimensional factor K is then brought forward based on physically the side wall constraint effect on the facade flame entrainment, to characterize the side wall effect on the flame height, by including the dimensionless excess heat release rate, the characteristic length scales of the opening as well as the side wall separation distance. The experimental data are shown to be well correlated by the proposed global factor. [Copyright &y& Elsevier]

• Use of the Cloud Analysis for the development of probabilistic fire demand models. • The LOCAFI localised fire model was used to model the effect of hydrocarbon pool fires. • Development of fire fragility functions of a steel pipe-rack. • The interstorey drift ratio – average maximum heat flux pair results the most efficient. This paper proposes a new method to build a probabilistic fire demand model (PFDM) to investigate the structural behaviour of a steel pipe-rack located within an industrial installation and exposed to a localised fire. The PFDM will serve to develop fire fragility functions to be used either in a fire risk assessment or in a fully probabilistic structural fire engineering (PSFE) framework. The cloud analysis (CA) was exploited to build a PFDM based on different engineering demand parameters (EDP) – intensity measures (IM) pairs. In particular, the analysis was applied to a prototype steel pipe-rack integrating an industrial plant in Italy. In order to cover a wide range of plausible fire scenarios and to introduce uncertainties in the fire model, 539 fire scenarios were examined by varying the fire diameter, the fire-structure distance and the fuel. The selection of the fire diameters was based on parametric analyses quantifying liquid flow through orifices and pipes. The thermal impact of the pool fires on the structure was analysed using the LOCAFI localised fire model and the thermo-mechanical response of the pipe rack was evaluated by means of finite element analysis. Based on the structural analysis outcomes, it was found that the interstorey drift ratio (ISDR) – maximum average heat flux impinging the structure (HF avg) EDP-IM pair was the most efficient and was also characterised by the highest relative sufficiency among the other pairs. Moreover, it has to be noted that for this type of case study, the CA revealed to be a viable option to build a PFDM. [ABSTRACT FROM AUTHOR]

• Amazon fires returned to levels observed when deforestation was twofold higher. • Efficient spatial allocation of fire brigades requires accurate fire prediction. • Accuracy is affected by unobservable time-fixed factors and spatial clustering. • Top fire municipalities were detected twice as accurately as in current practice. • Brigade allocation should consider the multidimensionality of fire predictors. The positioning of federal fire brigades in the Brazilian Amazon is based on an oversimplified prediction of fire occurrences, where inaccuracies can affect the policy's efficiency. To mitigate this issue, this paper attempts to improve fire prediction. Firstly, a panel dataset was built at municipal level from socioeconomic and environmental data. The dataset is unparalleled in both the number of variables (48) and in geographical (whole Amazon) and temporal breadth (2008 to 2014). Secondly, econometric models were estimated to predict fire occurrences with high accuracy and to infer statistically significant predictors of fire. The best predictions were achieved by accounting for observed and unobserved time-invariant predictors and also for spatial dependence. The most accurate model predicted the top 20% municipal fire counts with 76% success rate. It was over twice as accurate in identifying priority municipalities as the current fire brigade allocation procedure. Of the 47 potential predictors, deforestation, forest degradation, primary forest, GDP, indigenous and protected areas, climate and soil proved statistically significant. Conclusively, the current criteria for allocating fire brigades should be expanded to account for (i) socioeconomic and environmental predictors, (ii) time-invariant unobservables and (iii) spatial autocorrelation on fires. [ABSTRACT FROM AUTHOR]