Modelling of structures exposed to fires is prone to be heavily influenced by uncertainties in geometrical parameters, thermal material data as well as uncertainties in the boundary conditions. Assessing the effects and influences in variations of all the uncertain parameters is often cumbersome and traditional methods are impractical thus modelling of the total uncertainty is needed. Uncertainty Quantification with deterministic sampling is one possible way ahead to accommodate and evaluating the effects of uncertainties with as few repeated simulations as possible. In this paper the uncertainties stemming from error in the input data and boundary conditions on one example of a steel beam under four point bending exposed to fire is evaluated.

In this paper a coarse graining process is used to subsequently model large wildland fires, starting from a model of a single tree. The models are created using Wildland Urban Interface Fire dynamics Simulator (WFDS), and it is here found that reasonable fire spread in small forests can be obtained although the results are quite dependent on grid resolution as well as moisture content. In most realistic scenarios the computational volume is rather large yielding massive amounts of data. In using WFDS a rather small grid size is needed to appropriately model the fire spread this will be a severely limiting factor in creating large models.

As a natural material, the response of timber structures under normal conditions and to fire is subject to wide variability. Deterministic models therefore struggle to reflect the reality of the response of timber since small variations in input influence the output significantly. However it is relatively straightforward to quantify uncertainties in model inputs in order to determine the uncertainties in the model response by employing uncertainty quantification (UQ) techniques. UQ of structural response to fire traditionally employs Monte Carlo techniques (Eamon and Jensen 2013) which are computationally expensive for a large number of variables. Deterministic Sampling (DS) (Hessling 2013) is a relatively new efficient alternative method for UQ. DS assumes that a continuous probability density function can be replaced by an ensemble of discrete deterministic samples if the two representations have the same statistical moments. DS has been demonstrated applied to, e.g. CFD simulations (Anderson et al. 2016). This paper applies DS techniques to study glued-laminated (glulam) timber in fire. Results are compared with random sampling techniques to show the validity of this method in this application.

Glass has been overwhelmingly used for windows and facades in modern constructions, for many practical reasons, including thermal, energy, light and aesthetics. Nevertheless, due to the relatively low tensile strength and mostly brittle behaviour of glass, compared to other traditional materials, as well as to a multitude of interacting structural and non-structural components, windows/facades are one of the most fragile and vulnerable components of buildings, being representative of the physical line of separation between interior and exterior spaces. As such, multidisciplinary approaches, as well as specific fail-safe design criteria and analysis methods are required, especially under extreme loading conditions, so that casualties and injuries in the event of failure could be avoided and appropriate safety levels could be guaranteed. In this context, this paper presents a review of the state of art on analysis and design methods in use for glass facades, with careful consideration for extreme loading configurations, including natural events, such as seismic events, extreme wind or other climatic exposures, and man-made threats, i.e. blast loads and fire. Major results of available experimental outcomes, current issues and trends are also reported, summarising still open challenges.

The objective of this project was to address a request from the Standing Committee of Construction (SCC) to provide EC Member States regulators with a means to regulate the fire performance of façade systems based on a European approach agreed by SCC.

A localized fire is a fire which in a compartment is unlikely to reach flash-over and uniform temperature distribution. Designing for localized fires is generally more difficult than for flash-over compartment fires because of the complexity of the problem. There is also a lack of experimental data. We report here on a full scale test series on a steel column exposed to localizedfires. The setup is a 6 meters tall hollow circular column, I= 200 mm with a steel thickness of 10 mm. The unloaded column was hanging centrally above different pool fires. Temperatures of gas and steel were measured by thermocouples, and adiabatic surface temperatures at the steel surface were measured by plate thermometers of various designs. The results are compared with estimates based on Eurocode 1991-1-2 which in all cases studied overestimate the thermal impact for this setup. The input from plate thermometers was used to compute the steel temperatures using finite element methods. Excellent agreement was found if the radiation exchange within the column due to asymmetry of the exposure was taken into account.

Glass is seeing a growing interest as a structural material as a result of its relatively good strength to weight ratio and the obvious aesthetic benefits of its use in buildings. However due to the sensitivity of glass to thermal shock and the considerably temperature-dependent behaviour of interlayer materials as a result of their visco-elastic nature, the mechanical behaviour of laminated glass will be severely influenced by exposure to fire. Relatively little research has been conducted in the past to study the response of load bearing structural glass, and laminated glass in particular to radiant heating. This paper represents an effort to try to understand the effects of through depth radiation absorption and temperature conduction through laminated glass with a view to ultimately developing a model for studying load bearing glass exposed to elevated temperatures, such as those that would be expected in a fire. The paper reports on an experimental research programme in which several monolithic and laminated glass configurations were exposed to a radiant heat flux to study the different phenomena that occur upon exposure to fire conditions, including the ratios of absorbed, transmitted and reflected heat flux to the incident heat flux. The paper then presents a numerical heat transfer model which is developed based on these experimental results and that is able to determine the evolution of the temperature profile as a result of a given incident heat flux. The effectiveness of the heat transfer model is demonstrated through comparison with the temperatures measured during the experimental work.

We present the application of a simple probabilistic methodology to determine the reliability of a structural element exposed to fire when designed following Eurocode 1-1-2 (EC1). Eurocodes are being used extensively within the European Union in the design of many buildings and structures. Here, the methodology is applied to a simply-supported, reinforced concrete slab 180 mm thick, with a standard load bearing fire resistance of 90 min. The slab is subjected to a fire in an office compartment of 420 m2 floor area and 4 m height. Temperature time curves are produced using the EC1 parametric fire curve, which assumes uniform temperature and a uniform burning condition for the fire. Heat transfer calculations identify the plausible worst case scenarios in terms of maximum rebar temperature. We found that a ventilation-controlled fire with opening factor 0.02 m1/2 results in a maximum rebar temperature of 448°C after 102 min of fire exposure. Sensitivity analyses to the main parameters in the EC1 fire curves and in the EC1 heat transfer calculations are performed using a one-at-a-time (OAT) method. The failure probability is then calculated for a series of input parameters using the Monte Carlo method. The results show that this slab has a 0.3% probability of failure when the compartment is designed with all layers of safety in place (detection and sprinkler systems, safe access route, and fire fighting devices are available). Unavailability of sprinkler systems results in a 1% probability of failure. When both sprinkler system and detection are not available in the building, the probability of failure is 8%. This novel study conducts for the first time a probabilistic calculation using the EC1 parametric curve, helping engineers to identify the most critical design fires and the probabilistic resistance assumed in EC1. 

ABSTRACT The use of glass as a structural material has increased in the built environment over the last decades. Despite the large number of research projects and studies, it still poses difficulties in structural design. This particularly applies to the behaviour of glass in fire and under elevated temperatures since the available data on temperature dependent mechanical and thermal properties of glass is still limited. This contribution provides a brief overview of material properties of glass at elevated temperature and elaborates on current requirements for the fire safety included in standards.

The current paper reports about the progress in the ongoing European project IMPROVER (Improved risk evaluation and implementation of resilience concepts to critical infrastructure), in which a fundamental part is devoted to technological resilience concepts. Within the project a general methodology for resilience evaluation is developed, in which existing concepts in the field of structural engineering are aligned with non-technological domains (e.g. organizational and societal) contributing to resilience. A shift from protection to enhancing resilience leads to a shift in focus from traditional risk management towards crisis management. Some of these issues are exemplified here with the application on bridges as critical infrastructures.

Critical infrastructure is exposed to a wide range of hazards, capable to disrupt its operations in various degrees. This raises the question of which hazard scenario an operator shall use to assess the resilience of their critical infrastructure asset. Various techniques aiming to prioritize the various risks are commonly used in the literature. This study proposed an 8-step methodology, which aims to rank the risks of pre-defined hazard scenarios by eliciting the opinions of the stakeholders through a structured expert elicitation technique termed paired comparison. The novelty of the proposed technique is its ability to quantify the degree of disagreement regarding the ranking order of the scenarios and thus to capture the uncertainty associated with these risks.

The proposed methodology has been applied to four living labs, namely: the Oresund region, the port of Oslo, the A31 Highway in France and the potable water network in Barreiro. The applications aims to rank scenarios of natural and operational hazards according to their disaster- and emergency-risk. Despite the small number of participants, the results provide an excellent basis for further discussion regarding the most likely disaster or emergency risk scenarios. For most living labs, the ranking of the hazards using paired comparison was successful in identifying the scenarios associated with the highest risk. Overall, ranking the natural hazards according to their disaster- or emergency-risk has been associated with a higher degree of consensus than the ranking of the operational hazards reflecting on the higher complexity and perhaps the limited understanding of the later.

In more detail, snow storm is the hazard with the highest disaster risk for the A31 Highway. Similarly, earthquake is the hazard with the highest disaster risk for the water network in Barreiro. Three meteorological hazards ranked the highest for both the likelihood to occur and to cause disaster to the Øresund region. By contrast, the ranking of the hazards for the port of Oslo identified several scenarios with similar likelihood to cause disaster, which ranked very different in their likelihood to occur in the next 5 years. This raises question as to whether the most of least likely to occur scenarios is most suitable which can be answered in collaboration with the stakeholders.

With regard to the operational hazards, the contamination of the water in the water source or the distribution network due to an accident at the high-risk industrial SEVECO operations has been identified as the single scenario with the highest risk of disaster for the water network in Barreiro. Three events including a multiple day strike and two accidents in the wet bulk terminal have been identified as having the highest disaster risk for the port of Oslo. By contrast, no operational hazards can be identified as having the highest risk of occurrence for the A31 highway and the Øresund region

The fire resistance of a sprayed concrete inner lining for tunnels has been investigated experimentally and theoretically. During the initial first test on a section of nominal size 5 × 3 × 0.12 m3 the specimen maintained the integrity and insulation criteria during 180 minutes fire exposure with the Hydrocarbon fire curve. Also during the second test, where two specimens of half the size were tested, the integrity and insulation criteria’s were maintained but during this test the fire exposure was reduced during a period of the test due to a technical malfunction. The thermal properties of the sprayed concrete was shown by TPS measurements to be in the span of the values found in the Eurocode. Further on, calculations based on the Eurocode model including temperature dependent stress/strain was shown to give results on the safe side compared with measurements performed during the test. Stresses calculated in the supporting steel bars were 2 to 3 times higher than the measurements which is conservative. Key words: tunnels, fire, sprayed concrete

This paper presents a proposed analytical method for calculating the mechanical loading on a beam column connection in fire. The behavior of connections in fire has received considerable interest over the last decade since it is well known and demonstrated experimentally that composite steel concrete construction is able to adopt alternative load bearing mechanisms in fire as a result of large displacements. This global behavior is different from behavior which is studied in standard furnace testing and places additional loads on the supporting structure which must be able to support elements which are effectively 'hanging' in tension as opposed to supporting the load through shear and bending, as at ambient. First, this paper explores the mechanisms which lead to time varying mechanical loading on a beam / column connection in fire. Then a simple method for calculating a loading envelope of the connection is proposed. The analytical method is derived from fundamental principles of structural behavior at high temperatures and is a development of previous work published by the authors elsewhere. New developments presented include a discussion of the mechanisms which govern the response of composite structures during cooling following a fire and inclusion of these in the analytical model. The analytical method is then compared with the results of finite element analyses and is shown to compare favorably.

This paper details a round robin study of the calculated response of structures in fire. In this instance, the study is based on one of two fire tests which were conducted on steel beams in a horizontal fire resistance furnace. The two specimens in the tests were identical having come from the same cast flow. The tests were conducted according to EN 1365-3 and the steel beams had a total length 5.4 m, spanning 5.2 m. These tests also formed a part of a testing round robin, reported elsewhere. The calculations were conducted by round robin participants in two stages. In the first instance a prediction of the response was made without knowledge of the measured temperatures of the steel beam and with only the grade of steel and details of the test setup. In the second instance the participants were also given the measured elastic limit of the steel, which differed significantly from the elastic limit implied by the grade, as well as measured temperatures from the steel beam and the plate thermometers from the furnace and asked to refine their model. Statistical analysis of the round robin results are presented to illustrate the variation which arises in the results of calculations. The results of the round robin study serve to illustrate the fire research and testing community's capability for modelling this simple case as well as the uncertainty in the calculation results. The results of the calculation round robin are also compared with the testing round robin to illustrate the comparative certainty between testing and calculations.

This paper discusses the principles of performance based structural design and motivates the need for probabilistic assessment of the response of structures and an assessment of the consequences of failure. Using the results from a series of tests carried out at SP in Sweden, we extrapolate data required for the assessment of timber structures under a range of parametric fires. This data also includes information required to develop probabilistic models of the response of timber elements under different parametric fires. Using methodologies from the literature, we then carry out a reliability analysis of timber structures, considering uncertainties the timberresponse to fire. This is carried out using the first order reliability method. We show that the opening factor has an influence on the reliability of timber structures, as a result of the rate of heating in a parametric fire exposure. A minimum reliability, evolving over time, is seen to occur at an opening factor of 0.14m1/2. Finally, we propose a modification to the Eurocode target reliability indices that allows these to be used as a target reliability index for structures exposed to fire. The proposed modification is dependent on the floor area and the method is exemplified here for a range of floor areas and its application to timber structures is illustrated.

Timber is an desired material for structural applications due to its green credentials and attractive external appearance. Fire safety design of timber structures is largely limited to considering the exposure of elements to the standard fire, to which timber demonstrates exceptional resilience. This paper reports on a series of tests which were carried out with the intention of exploring the impact of non-standard fires on timber elements. Because of the natural variation in timber elements, the tests and the resulting analysis of the test results were conceived and designed in such a way that as much information about the statistical distribution of the response of the elements as possible could be obtained. The resulting testing programme comprised four furnace fire tests, each of eight loaded timber beams, with three different temperature time curves: two standard fire tests, one long-cool parametric fire and one short-hot parametric fire. The reduced cross section method for structural calculations is extended in this paper to parametric fire exposures, and the results of the tests are compared with this method. It is shown that the thickness of the zero-strength layer is dependent on the temperature time curve to which the timber is exposed in the furnace and that the 7 mm zero-strength layer prescribed in EN 1995-1-2 may be un-conservative for members in bending. For the cases studied, the zero-strength layer thickness in bending is shown to be around about 15 mm under standard fire exposure and 16 mm under exposure to a long cool parametric fire. Conversely, the zero-strength layer is only 8 mm deep under exposure to a short hot parametric fire. This has implications for the design of timber elements not only for parametric fire exposure in enclosures, but also perhaps for the use of timber elements in large open structures such as halls or arenas where more localised fire exposure or travelling fire exposure may be expected.

The Pacific Earthquake Engineering Research (PEER) Center's Performance Based Earthquake Engineering (PBEE) framework is well documented. The framework is a linear methodology which is based upon obtaining in turn output from each of the following analyses: hazard analysis; structural analysis; loss analysis, and finally decision making based on variables of interest, such as downtime or cost to repair. The strength of the framework is in its linearity, its clear flexibility and in the consideration of uncertainty at every stage of the analysis. The framework has potential applications to other forms of extreme loading; however in order for this to be achieved the 'mapping' of the framework to the analysis of structures for other loading situations must be successful.This paper illustrates one such 'mapping' of the framework for Performance Based Fire Engineering (PBFE) of structures. Using a combination of simple analytical techniques and codified methods as well as random sampling techniques to develop a range of response records, the PEER framework is followed to illustrate its application to structural fire engineering. The end result is a successful application of the earthquake framework to fire which highlights both the assumptions which are inherent in the performance based design framework as well as subjects of future research which will allow more confidence in the design of structures for fire using performance based techniques.This article describes the PEER framework applied to structural earthquake design then follows the framework from start to completion applying suitable alternative tools to perform each stage of the analysis for structures in fire.

The impact of disasters and crises in Europe is char-acterised by a highly interconnected society–a society which is increasingly reliant on critical infrastructures providing services which are centralised, if not terri-torially then contextually. Through cascading failures through interdependent systems the indirect consequences of natural and man-made disasters may be more severe than expected.

This paper explores the concept of Critical Infrastructure (CI) resilience and its relationship with current Risk Assessment (RA) processes. It proposes a framework for resilience assessment of CI, which integrates the resilience paradigm into the RA process according to ISO 31000. The framework consists of three levels, namely (a) asset (focus on individual CI assets), (b) system (focus on dependencies between CI assets) and (c) national or regional (focus on societal aspects). It is applicable to individual CI or their combinations, accounting both for existing RA processes, for interdependencies and their effect on interconnected CI, while at the same time employing current, available resilience analysis tools and methodologies. This approach is also compatible with the current European guidelines for national RA applied by the EU Member States. © 2017 Taylor & Francis Group, London.

This report summarises the results of a project which was intended to study the response of hollow core and prestressed concrete construction exposed to fire. Two fires in the past 12 years highlighted the susceptibility of this type of construction to fire, a car park fire in Rotterdam and a department store fire in Vantaa. The car park fire has been extensively studied elsewhere and has led to much research on the response of hollow core construction exposed to fire. The department store fire has been less well reported.The report gives a short overview of these two fires, and then reports on a literature review of the response of prestressed and hollow core concrete construction exposed to fire. The comprehensive analyses carried out elsewhere are an excellent starting point for further study.The report then goes on to discuss the application of different concrete models to prestressed concrete construction. Other work reported elsewhere shows that results of modelling prestressed concrete construction exposed to fire is very susceptible to the concrete model which is used, and so finite element modelling of two fire tests of hollow core slabs is carried out to evaluate the impact of the concrete model on this type of construction. It is found that an explicit formulation of transient strain in concrete has a significant impact compared with an implicit formulation of transient strain, in the overall behaviour of the hollow core slab and also in the response of, e.g. the prestessing tendons.Finally, an analytical method for assessing the capacity of prestressed concrete construction under ambient conditions is extended to apply to hollow core slabs exposed to fire. This is used to compare the response of prestressed hollow core slabs to prestressed monolithic slabs exposed to fire and to study different parameters which influence the response and the capacity of hollow core units in fire.Based on the results of the analytical modelling, it can be seen that hollow core concrete construction experiences a far higher thermal gradient and resulting thermal moment than monolithic concrete construction. This is a result of the geometry of the cross section which effectively traps heat in the lower flange. This in turn leads to a faster loss of prestressing force on the cross section than in a monolithic concrete section. This contributes to a faster reduction in the ultimate moment of hollow core slabs compared with monolithic concrete construction.However changing the prestressing tendon depth has a significant effect on the evolution of the ultimate moment under fire exposure. A shallow tendon with little cover has higher capacity at ambient and under fire exposure for a short duration, whereas a tendon with a large amount of cover has a lower ambient capacity, but retains more of this capacity for longer under fire exposure.The analytical method which is proposed is not capable of capturing the nuances in behaviour and response of the finite element method which is reported, nevertheless it is useful in helping to understand the response of prestressed concrete construction exposed to fire. It may also be useful as a screening tool for evaluating the impact of different design options either in hollow core slabs themselves or when making choices in the design phase. However, both the analytical and the numerical modelling suffer from a lack of good quality experimental data which could be used for their evaluation and this should be considered in the future.Key words: prestressed concrete, hollow core slabs, fire, modelling

This paper reviews the phenomena of concrete behavior which is captured in the material data of the Eurocode and reviews additional phenomena which may be included to improve results incertain cases. As a case study, a series of tests which were conducted by Anderberg and Thelandersson in the 1970's in Sweden on concrete samples are studied using first of all the temperature dependent material model which is used in the Eurocodes. The impact of load induced thermal strain is discussed through comparison of the implicit model which is used in the Eurocode and a simple explicit model based on the test results.

This report is the second of two reports into the Tisova fire test. It compares the results of three different groups’ attempts to model the temperature response of the structure in Tisova which was subject to a large scale travelling fire test. Generally it is observed that the different approaches have relatively close results, although one shows systematically hotter temperatures closer to the heated surface than the others; and differences between all three increase further from the heated surface.A comparison between the average calculated results and the experimental results is also shown for illustration. While an absolute comparison is not attempted because of experimental errors present the results do show the possible need for further data to support the heat transfer analysis required to carry out structural design for travelling fires.

This report is a summary of the Tisova fire test, conducted in the Czech Republicin January 2015. It is the first of two reports into these test, and describes thebuilding, the experimental setup and discusses the results obtained on the day ofthe test. The results are discussed with a specific focus on the travelling nature ofthe fire in the building, since one of the objectives of the test was to provide anexperimental data set for validation of traveling fire models. To this end theproject was partially successful, since as is discussed a number of factorscontributed to slow fire spread and the need to alter the conditions of the testwhile it was ongoing by adding a mixture of diesel and gasoline to part of the fuelbed. This was needed in order to ensure that the test fulfilled the second of itsmain objectives – to provide a dataset of the response of a real structure exposedto a structurally challenging fire for the purposes of carrying out a round robinexercise of the response. This round robin will be reported in the second of thisreport series.Key conclusions from the test were that while we observed a travelling fire, thefire dynamics which lead to this and which contribute to the evolution of such afire need to be better understood.

Recent trends in structural fire engineering research have focussed on the response of buildings with large open plan spaces to so-called travelling fires. These fires travel horizontally across the floor plate of a building and result in time and spatially varying thermal exposure and response of the structure to the fire. What has received little attention, however, is the effect that non-uniform thermal exposure has on columns. Recent tests conducted at SP demonstrated the effect of a small non-uniformity of thermal exposure, resulting in a thermal gradient of around 1 °C/mm, on a column exposed to a pool fire. The curvature resulting from a non-uniform thermal exposure where the column is pinned, or in cases where the column is partially restrained, will result in an eccentricity in the column's loading and large second order effects. This paper describes the effect of thermal exposure varying in both the horizontal and vertical axes to columns by means of including this thermal boundary in a solution of classical Euler beam theory. The resulting solution allows for a variation in the stiffness of the rotational restraint at both ends of the column and a non-uniform temperature exposure through the column's section and along its height. The resulting equations help to understand better the impact of the assumptions of 'lumped capacitance' on steel columns, suggesting a challenge to this assumption in some instances, as well as to enhance understanding of the impact of non-uniform fires on steel columns.

This paper reports on two experiments conducted in a fire resistance furnace to study the differences in the boundary conditions, the fire dynamics and the fuel required to run the furnace when a combustible timber specimen as opposed to a non-combustible concrete specimen is tested. In both experiments measurements were taken in the furnace to evaluate the difference in the environments of the furnace and the response of the elements being tested. These include non-control plate thermometers distributed throughout the furnace; O2, CO2 and CO gas measurements taken at different distances from the specimen surface and in the furnace exhaust; instrumentation of one of the bricks comprising the furnace lining with thermocouples at different depths from the exposed surface; and mass loss of the combustible timber specimen. Thermal exposure of elements in a furnace is discussed, as well as the impact of the different materials on the similarity of thermal exposure. This is done through analysis and discussion of the different measurements taken and the apparent influence of the specimen being tested on the boundary condition of the heat diffusion equation. We conclude that; (1) the fire dynamics in a furnace are dependent on the specimen being tested; (2) that the test with the combustible specimen requires less fuel flow to the burners such that the control plate thermometers follow the ISO 834 temperature–time curve compared to the non-combustible specimen, however that this is not only a result of the combustibility of the specimen but is also a consequence of the different thermal inertia of the two materials; (3) that the boundary condition for heat transfer to a test object in furnace tests is dependent on the properties of the specimen being tested; and (4) that the timber when placed on the furnace experiences smouldering combustion after the char layer has formed. A fire resistance test of combustible construction of a given period represents a significantly less onerous test in terms of energy absorbed or fuel made available than one of a non-combustible construction, implying that the existing fire resistance framework may not be appropriate for timber structures and that an alternative approach may be required.

Modern socio-technical systems are increasingly characterised by high degrees of interdependencies. Whereas these interdependencies generally make systems more efficient under normal operations, they contribute to cascading effects in times of crises. Therefore, challenges for emergency preparedness and response are growing significantly. An escalating incident in such an environment can lead to severe cascading effects and quickly become extremely difficult for emergency services to handle. The more complex the environment where an incident is evolving, the more vulnerable the system, the greater the risk for escalation and cascading effects. In such instances the incident management needs to be as efficient as possible and build on up to date decision support information. New strategies, structures and methodologies are, therefore, needed to meet these new challenges, including cross border cooperation in conducting operations and providing or receiving support across borders.