Annually, several concrete structures, such as buildings, bridges, parking garages, tunnels, etc. are exposed to fires. Many fires are small, for example single car fires in tunnels. These fires do not affect the load carrying capability of the concrete structure and thus minor or no reparations are required. In modern concrete for civil engineer applications the use of Polypropylene fibres (PP-fibre) to reduce fire spalling is growing. Some studies have been carried out which indicate that the use of PP-fibres will not affect the durability of the concrete. But in case of a fairly moderate fire exposure, a fire exposure that does not lead to structural damage, the PP-fibres can potentially lead to reduced durability. During low intensity fires or at long distances downstream a large fire in a tunnel the PP-fibres melts and form channels in the concrete. After such degradation of the PP-fibres it is plausible that accelerated damage may occur when moisture, de-icing salts and carbon dioxide can more easily penetrate the concrete. In this experimental study the chloride migration and the capillary suction are studied in moderately heated concrete containing PP-fibres. The chloride migration tests were conducted with heated samples with and without PP-fibres. The capillary suction tests were even conducted with different fibre contents. As a reference the results are compared with results from unheated concrete. The aim of the project is to define whether or not measures have to be taken to repair concrete structures after small fires and at long distances downstream from large fires in tunnels. If the durability is affected the costs and consequences of not repairing and refurbishing after the fire can potentially be very high especially after a fires in very long tunnel.

Annually, several concrete structures, such as buildings, bridges, parking garages and tunnels are exposed to fires. An assessment is then necessary to decide whether the structure can be repaired or needs to be replaced. In a recent research project, recommendations for assessments of fire exposed concrete structures have been developed. The recommendations are based on a literature survey, results from an experimental study, where ultrasonic measurements, microscopy, Digital Image Correlation (DIC) measurement on loaded core samples were used and practical experience of real post-fire structural assessments. A refined assessment of the fire damage is obtained by combining these test methods.

In Sweden the responsibility for environmental damage when emergency responders are called to an incident is increasingly focussing on the responders. The problem is that most incident response personnel do not have the training and expertise to assess the environmental consequences of their suppression operations. The Fire Impact Tool was developed for training responders about how fire effluents and suppression media affect air, surface/groundwater and soil. The tool has three interdependent parts: fire models (for vehicles and enclosures), an environmental risk assessment (ERA) model for local impacts, and a life cycle assessment (LCA) model for global impacts. Users can create two scenarios that are compared with a reference case in which responders arrive at the incident and prevent the fire from spreading beyond the vehicle or enclosure but do not suppress the fire. The Fire Impact Tool is not intended for use during an actual fire incident. This work does not answer every question for every possible fire scenario, but it does provide a framework for deeper, broader, more comprehensive training and pre-planning. This is a necessary step toward a future in which responders are prepared to make informed decisions about firefighting strategies and tactics that include environmental consequences.

Façade fires do not occur often (in comparison to other major structure fires) but in recent years there have been a number of spectacular façade fires in high rise building such as the recent fire in Grenfell Tower, London.Under-ventilated compartment fires may cause flames to spill out of window openings impinging the façade, thus devastating façade fires may start on one floor leap-frogging to adjacent floors. It is therefore necessary to limit or delay fire spread to higher floors. Requirements built on large scale fire testing may decrease the risk of these types of fires provided that the building is constructed according to the specifications provided by the manufacturer. Different countries have different regulations and tests for façades. New materials and façade systems are continuously introduced which might call for an update of these tests and regulations.This report summarizes experimental and modelling efforts in characterizing the fire safety of façades using the Swedish SP Fire 105 and the British BS 8414 methods. Recent experimental results and modelling is presented exploring the variations in the fire exposure, fire load and the fuel used. The fire source and the heat exposure to the façade are characterized by additional temperatures measured by plate thermometers while some other aspects are only treated in the numerical study such as a change in fuel. It is found that the results from the BS 8414 are largely affected by wind and climate since the experimental test was performed outdoors, moreover fire spread on wooden façades is also briefly discussed.In order to obtain a deeper understanding of the test methods and the results CFD (Computational Fluid Dynamics) Modelling in FDS was used. The models were based on measured input parameters including uncertainties and an assessment of the impact of said uncertainties. The models could often reproduce the experimentally found temperatures qualitatively and quantitatively. A detailed discussion on the regulations and the tests that lead to the SP Fire 105 test method is also presented. Summaries of the façade testing methods and conditions in other European countries are presented in the appendices.Finally possible ways forward in updating the façade testing and regulations are discussed.

A comparison between full‐scale façade fire tests where SP Fire 105 and BS 8414‐1 were used regarding repeatability and the use of modeling to discern changes in the setups is presented. Two test series according to BS 8414‐1 were repeated outside using the same façade systems on 2 different days, whereas for the SP Fire 105 a set of common façade systems in Sweden were tested indoors. In particular, the results show that the wind around the test setup may have a significant impact on the tests and that the heat exposure to the façade surface will depend on the thickness of the test specimen where an increased temperature in front of the façade, and a decreased temperature on the façade 2.1 m above the fire room, is observed experimentally. The heat exposure to the test specimen varies to a more limited extent when an uncontrollable free burning fire source is used (in this study heptane and wood, respectively) and that this variation increases when wind is present.

In this paper, a comparative simulation study on 3 large‐scale facade testing methods, namely,the SP Fire 105, BS 8414‐1, and the ISO 13785‐2 methods, is presented. Generally goodcorrespondence between simulations and experimental data has been found, provided thatthermal properties of the facade material and heat release rates are known; however, thecorrespondence deviates in close proximity of the fire source. Furthermore, a statistical ensemblefor evaluating the effects stemming from uncertainty in input data is used. Here, it wasfound using this statistical ensemble that the variability was smaller in the ISO 13785‐2compared to the BS 8414‐1 method. The heat release rates (HRR) used in the simulations wereadopted from measurements except for the ISO method where the information in the standardwas used to approximate the HRR. A quantitative similarity between the HRR in the ISOmethod and the British method was found.

In this paper a comparison between test and modelling results are performed for two large-scale façade fire testing methods, namely SP Fire 105 and BS 8414-1. In order to be able to compare tests and modelling the uncertainties have to be quantified both in the test and the modelling. Here we present a methodology based on deterministic sampling to quantify uncertainties in the modelling input. We find, in general good agreement between the models and the test results. Moreover, temperatures estimated by plate thermometers is indicated to be less sensitive to small variations in model input and is thus suitable for these kind of comparisons.

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.

In two recent papers [1, 2] the fire dynamics in a test rig for façade constructions according to the test method SP Brand 105 [3, 4] was investigated both experimentally and numerically. The experimental setup simulates a three-story apartment building (height 6.7m, width 4m and depth 1.6m), with external wall-cladding and a "room fire" at the base. The numerical model was developed in the CFD program Fire Dynamics Simulator (FDS) [5] with analogous geometry and instrumentation. The general features of the fire test were well reproduced in the numerical model however temperatures close to the fire source could not be properly accounted for in the model. In this paper the bi-directional probe measurements are elaborated on and the test used in Ref. [1] is revisited using different heat release rates in the numerical model. The velocity of the hot gases along the façade was well reproduced by the simulations although some deviations were found.

In this work, a review of current literature on artificial intelligence (AI) and more specifically machine learning (ML) is presented. ML is illustrated by two case studies where artificial neural networks are used for regression analysis of 110 spalling experiments and 81 Fire Dynamics Simulator (FDS) models of tunnel fires. Tunnel fires are often assessed by fire safety engineers using time-consuming simulation tools where a trained model has the potential to significantly reduce time and cost of these assessments.

A regression model based on a neural net is used to study small scale spalling experiments and similar accuracy compared to least-square fits are obtained. The result is a function based on 14 determining experimental parameters of spalling and result in, spalling times and depths. It is a relatively small effort to get started and set up models, comparably to regular curve fitting. In this first case study the training times are short, it is thus possible to establish how the model performs on average.

The 81 tunnel fire simulations are trained using a similar neural net however it takes considerable time to organize data, creating input, target data of the desired format and training. Here, it is also crucial to normalize the data in order to have it in a suitable format when training. 

It should be noted that ML is often an iterative process in such a way that it may be difficult to know what settings will work before starting the process. It is equally important to illustrate and get to know the data, e.g., if there are large differences or orders of magnitude differences in the data. A normalization procedure is most often practical and will give better predictions.

The fire resistance of concrete structures is generally good, but for some types of concrete fire spalling can reduce the fire resistance significantly. Therefore, methods are needed to predict whether a concrete will spall when exposed to fire and the severity of spalling.

The objective of the present project was to develop an intermediate scale test method for the evaluation of the spalling behavior of concrete. The test method shall be cost effective and enable screening of different concretes before a full scale approval test is performed. A number of different intermediate scale test methods have been evaluated regarding the precision to reproduce the spalling behavior of that observed in full scale tests.

Of the different test specimen shapes and methods, a circular test specimen where the concrete is casted in a steel tube has shown the best correlation to the full scale tests performed. This specimen is easy to produce, and the fire test can be performed on a small furnace.

Three large scale façade tests in accordance with SP Fire 105 as well as an ad hoc SBItest have been carried out. The façade tests included an inert façade made of lightweightconcrete, one façade with a plywood cladding and finally a façade with plywood claddingwith a fully ventilated cavity behind the cladding. The SBI test was made with plywoodwithout ventilation cavity. The aim of the tests was to perform well controlled tests withnumerous of measurements including heat release rate, heat from the combustionchamber, temperature on the façade surface, heat flux, plume temperatures andtemperatures in the ventilation cavity. The results from the tests will be used forvalidation of simulation techniques as well as input for further development of the façadetest methodology.Conclusions from the study were that the surface temperature for charring of the plywoodcladding in this configuration was in the region of 300 °C and that the energy releaseoriginated from the façade during the test was almost twice as high when there was a20 mm wide cavity behind the plywood cladding.Key words: fire test, facade, wood, ventilation cavity

Programmet ”IMI-verktyget” (se länk till höger) är utvecklat för att ge räddningstjänst, studenter och forskare ett verktyg för att öka kunskapen angående konsekvenserna av taktiska val vid respons till en brand, exemplifierad av några fordons- och rumsbränder.

I rapporten till höger (”fulltext”) beskriver hur verktyget fungerar och innehåller också exempel på datorlabbar som skulle kunna genomföras inom en brandingenjörsutbildning eller räddningsledarutbildning.

Structures may collapse during the cooling phase of a fire, yet standard furnace tests only measure the response under heating. There lacks experimental test protocols and design methods to assess resistance until burnout. This paper describes a new experimental approach for burnout resistance evaluation, reports experimental data on loaded reinforced concrete columns in furnace tests with cooling down phases, and presents numerical models of the tests. The test results show that columns designed for a standard fire resistance of 60 min exhibited a fire resistance of 83 min in the furnace but failed during the cooling phase when the burners were shut off after 72 min while the load was maintained. Two other specimens survived exposure to heating of 45 and 55 min, respectively, and their residual capacity was measured. Finite element analyses show agreement with the tests, showing applicability of numerical methods for evaluating burnout resistance of concrete columns. These findings demonstrate experimentally that delayed thermal-mechanical effects can jeopardize structural stability in real fires, and provide a framework to measure these effects. Moving beyond fire resistance to quantify the response until burnout will support designs for safety of occupants and firefighters throughout the fire and promote repairability and resilience. 

This paper describes fire tests on loaded glued laminated timber columns in which the structural response was measured during the heating and cooling phases. Identical columns with 280 × 280 mm2 cross-section and 3.7 m length were tested under various heating durations in a standard furnace to investigate integrity to full burnout. Two of the columns were subjected to ISO 834 heating until failure and their measured fire resistance was 55 and 58 min, respectively. Two columns were subjected to 15 min of ISO 834 heating followed by controlled cooling; these columns failed during the cooling phase, respectively after 98 and 153 min. Flame self-extinction occurred after approximately 40 min while smoldering continued locally. Two columns tested under 10 min of ISO 834 heating both survived the defined heating–cooling exposure. Thermocouples inside the columns show sustained temperature increases for hours after the end of the heating phase. These full-scale furnace experiments show that timber columns may fail during the cooling phase after exposure to standard heating for about 25% of the standard fire resistance duration. These results, in line with previous numerical predictions, highlight the need for further investigation into fire safety until full burnout for timber structures. 

In the present study the behaviour of four intumescent systems for steel was investigated experimentally. The main purpose of the study was to determine the behaviour of the systems during different fire scenarios including standardized furnace testing, tests in cone calorimeter and ad hoc tests including ceiling jets and fire plumes. The experimental campaign shows that two of the investigated systems did perform very poorly in the furnace tests compared to what they were designed for, despite being the systems having the best swelling in the cone calorimeter tests. This highlights the importance of adhesion at high temperature for this type of systems. Since adhesion is crucial a more relevant evaluation for this type of systems ought to be a test where the flows around the specimen can be characterized and controlled, i.e. a ceiling jet or a fire plume scenario. This is especially important as steel protected with intumescent systems are often used in large open spaces where local fire plumes and ceiling jets are expected.Key words: intumescent paint, steel, alternative exposure

This paper presents a historical overview of fire spalling of concrete between the mid-1800s through to modern time. Several of the observations presented are put into a modern context by additional discussion.