Endre søk
Begrens søket
23456 201 - 250 of 268
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 201.
    Rush, David
    et al.
    University of Edinburgh, UK.
    Lange, David
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Towards a fragility assessment of a concrete column exposed to a real fire – Tisova Fire Test2017Inngår i: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 150, s. 537-549Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fires can cause substantial damage to structures, both non-structural and structural, with economic losses of almost 1% GDP in developed countries. Whilst design codes allow engineers to design for the primary design driver, property protection is rarely, if ever, designed for. Quantification and design around property protection has been used for some time in the seismic community, particularly the PEER framework and fragility analyses. Fragility concepts have now started to be researched predominantly for steel-composite structures, however, there has been little to no research into the quantification of property protection for concrete structures, whether in design or in post-fire assessments of fire damaged structures. This paper presents selected results from the thermal environment around, and the thermal response of, a concrete column from a large scale structural fire test conducted in Tisova, Czech Republic, inside a four-storey concrete frame building, with concrete and composite deck floors. From the results of the fire test, assessments of the fire intensity are made and used to model the potential thermal profiles within the concrete column and the implications that high temperature might have on the post-fire response of the concrete column. These thermal profiles are then used to assess the reduction of the columns cross-sectional area and are compared to a quantified damage scale for concrete columns exposed to fire. This analyses presented herein will also show that common methods of defining fire intensity through equivalent fire durations do not appropriately account for the complexities of the thermal and structural response of concrete columns exposed to a travelling fire

  • 202.
    Rød, Bjarte
    et al.
    UiT The Arctic University of Norway, Norway.
    Barabadi, Abbas
    UiT The Arctic University of Norway, Norway.
    Ayele, Yonas Zewdu
    UiT The Arctic University of Norway, Norway.
    Lange, David
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Honfi, Daniel
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Droguett, Enrique López
    University of Chile, Chile.
    Probabilistic metric of infrastructure resilience considering time-dependent and time-independent covariates2017Inngår i: Safety and Reliability - Theory and Applications - Proceedings of the 27th European Safety and Reliability Conference, ESREL 2017, CRC Press/Balkema , 2017, s. 1053-1060Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In recent years, the importance of resilient critical infrastructures has become more evident. More frequent extreme weather conditions and human-induced disasters, such as terror attacks, cause severe damage to infrastructures. It is important to be able to withstand such events, but perhaps even more important be able to bounce back and rapidly recover. In this work, resilience is formulated, in a pragmatic way, as a combination of the reliability of infrastructure elements, vulnerability and the recoverability of the failed components. To be able to characterize the recovery time, there is a need to know the reliability and vulnerability of the infrastructures, i.e. their drop in performance in different scenarios with different stress level. Moreover, recovery time and vulnerability can be affected significantly by different factors such as location, seasonal effects, recovery crew available etc. Hence, the trajectory of the loss in performance and the recovery may have different paths depending these associated factors, meaning that resilience prediction model must be able to capture these factors. However, resilience studies are not well detailed regarding the effect of time dependent and time independent influence factors. The proposed formulation makes it possible to predict the resilience of a (critical) infrastructure with multiple failure mechanisms, different types of vulnerability process, and recovery actions with time-dependent and time-independent covariates. © 2017 Taylor & Francis Group, London.

  • 203.
    Rød, Bjarte
    et al.
    UiT The Arctic University of Norway, Norway.
    Pursiainen, Christer
    UiT The Arctic University of Norway, Norway.
    Reitan, Nina Kristine
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Storesund, Karolina
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Lange, David
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Mira da Silva, Miguel
    INOV INESC Inovação, Portugal.
    Evaluation of resilience assessment methodologies2017Inngår i: Safety and Reliability - Theory and Applications - Proceedings of the 27th European Safety and Reliability Conference, ESREL 2017, CRC Press/Balkema , 2017, s. 1039-1052Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There are a wide range of different frameworks and methodologies for analysing Critical Infrastructure (CI) resilience, covering organisational, technological and social resilience. However, there is a lack of a clear methodology combining these three resilience domains into one framework. The final goal of the ongoing EU-project IMPROVER, ‘Improved risk evaluation and implementation of resilience concepts to Critical Infrastructure,’ is to develop one single improved and easy-to-use critical infrastructure resilience analysis tool which will be applicable within all resilience domains and to all types of critical infrastructure. This article presents part of this work, in which IMPROVER comprehensively evaluated, by demonstration and comparison, a selection of existing resilience methodologies in order to integrate their best features into the new methodology. The selected methodologies were The Benchmark Resilience Tool (BRT) (Lee et al., 2013), Guidelines for Critical Infrastructures Resilience Evaluation (CIRE) (Bertocchi et al., 2016) and the Critical Infrastructure Resilience Index (CIRI). The latter was developed within the consortium (Pursiainen et al., 2017). The results show that it is hard to evaluate and compare the different methodologies considering that the methodologies are not aiming to achieve the same thing. However, this evaluation shows that all the methodologies have pros and cons, and that the IMPROVER project should aim at combining, in so far as is possible and commensurable, the identified pros while avoiding the identified cons into a Critical Infrastructure resilience assessment framework compatible with the current guidelines for risk assessment in the Member States. © 2017 Taylor & Francis Group, London.

  • 204.
    Sanchez, Luis
    et al.
    Chalmers University of Technology, Sweden.
    Ringsberg, Jonas
    Chalmers University of Technology, Sweden.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Effective use of composite marine structures: Reducing weight and acquisition cost: Chapter 62019Inngår i: Marine Composites : Design and Performance  (A volume in Woodhead Publishing Series in Composites Science and Engineering) / [ed] Richard Pemberton, John Summerscales and Jasper Graham-Jones, 2019, s. 161-183Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Composite structures are a way to reduce the operational costs of a vessel or to increase its potential revenue. However, depending on the design of the vessel, its operational profile, and the business model of the owner, the benefits brought by a composite structure may not justify its acquisition cost. This paper presents a number of investigations aimed at reducing the acquisition cost of marine composite structures and maximizing their benefits through a more effective use of composite materials (in other words, weight reduction of the composite structure). The investigations cover three areas of opportunity for doing so: material safety factors, material characterization, and numerical optimization of large composite structures. The following conclusions are drawn from the investigations: motivating a reduction of material safety factors through probabilistic analyses is unpractical at best, and questionable at worst; improving the material characterization of textile composites is easy, relatively costless, and can modestly reduce structural weight through better material property values; numerical optimization of large composite structures is cumbersome, but feasible, and holds the greatest potential increasing the economical attractiveness of composite marine structures.

  • 205.
    Sandinge, Anna
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Blomqvist, Per
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Dederichs, Anne
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Markert, Frank
    DTU Technical University of Denmark, Denmark.
    Methods for accelerated ageing of composite materials: a review2018Inngår i: Nordic Fire & Safety Days, 2018Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    New materials and designs enter the market every day. They have a great market potential needed for many applications. The future market for development and production of fibre reinforced composite materials (lightweight materials) is very promising, not only within advanced application such as aeronautics, but also in maritime industries, on modern ship vessels and in railway vehicles. As a result of this it is important to know the material properties and fire behaviour in order to ensure a high safety level [1].Materials are tested as “new” and un-aged, which means testing is performed on newly produced products and materials. Very little research has been done regarding fire performance of materials after aging [5].Accelerated ageing can be performed with different aspects and in numerous ways. One type of these can be called weathering and there are mainly four basic types of this ageing used for products and materials. They are: thermal ageing, exposure of high temperature during a selected time; moisture ageing, exposure of water or moisture; UV exposure, and radiation ageing. [5]These types of ageing can be performed in many ways and combinations. For example, thermal ageing can be performed at a selected temperature and time. But it can also be one part of a climate cycling were you have fixed periods with temperature exposure followed by moisture exposure and UV exposure. This cycle can be repeated a numerus of times [7].The degradation of composite materials and change in properties is slow at room temperature. It gets faster with increased temperature. Accelerated ageing is an intentional way to expose materials and products to a proper simulation of long-term usage. Within a few days, weeks or months the damage and degradation of the materials can occur, which normally would be after years in normal climate and after normal usage. Accelerated ageing can cause the material properties to get worse, and an undesirable loss of functionality may be evolved [4].The behavior and material properties of fibre reinforced composites, after exposure of aggressive environmental conditions, shows changes, compared to new materials. After exposure of moisture, the fibres may result in damage and the material structure might be changed. After exposure of moisture and high temperature the durability of the composite is reduced [2].The Arrhenius Rate Law of accelerated ageing can be used to correlate the time in ageing climate. A generalization, supported by the Arrhenius Rate Laws, is that for a reaction in room temperature, the reaction rate doubles every 10°C increase in temperature [6].The objective of this work is to gather the most common methods to perform accelerated ageing, to see the variations between the methods and within the method.

  • 206.
    Sandström, Johan
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Simulation and calibration of rubber materials for seals2018Rapport (Annet vitenskapelig)
    Abstract [en]

    Finite element (FE) simulations of how rubber materials for seals behave over time isperformed. The application is seals for nuclear power plants where seals are exposed toelevated levels of ionizing radiation and temperature.A major challenge for the simulations is to find an appropriate material model for the rubbermaterials and how to calibrate it to experiments. Here is a material model proposed that caninclude effects like creep, permanent set, and temperature dependence. Calibration of materialmodels for relaxation tests on EPDM rubber is performed and presented with good results.Further modelling to include more effects in the material and to simulate leak and tightness ofseals are proposed.

  • 207.
    Sandström, Johan
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Simulation of rubber materials for seals in use in nuclear power plants2019Rapport (Annet vitenskapelig)
    Abstract [en]

    Finite element (FE) simulations of how rubber materials for seals behave over time is performed. The application is seals for nuclear power plants where seals are exposed to elevated levels of ionizing radiation and temperature.

    A major challenge for the simulations is to find an appropriate material model for the rubber materials and how to calibrate it to experiments. Here is a material model proposed that can include effects like creep, permanent set, and temperature dependence. Calibration of material models for relaxation tests on EPDM rubber is performed and presented with good results. Simulations of leak and tightness of seals are evaluated and some initial observations on the effects temperature and ageing on the tightness are made.

  • 208.
    Sandström, Johan
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Albrektsson, Joakim
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Composite materials for railways2019Inngår i: EUROMAT: European Congress And Exhibition On Advanced Materials And Processes, Boutersem, Belgium, 2019Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Introduction/Purpose

    Europe’s railway industries require a step change in technologies and design for the next generation of railway vehicles in order to remain competitive globally. One way is use of composite materials that can reduce the weight of railway vehicles. Safety regulations for fire, smoke & toxicity requirements in the railway sector limits which materials that can be used for the composites and require special flame-retardant additives. The mechanical properties need to be asserted to reach the demands given by railway standards such as EN 12663. These standards are written for metallic materials requiring adaptation when designing and testing with composite materials.

    To address this, the EU funded project Mat4Rail – “Designing the railway of the future: Fire resistant composite materials and smart modular design” have been formed. It is part of the Shift2Rail program.

    Methods

    To find composites that meet the demands for fire safety and high mechanical strength, different combinations of resins and fibers are tested. The resins that are investigated are epoxies, benzoxazines and hybrid chemistry together with additives for enhanced fire performance. The fibers that are investigated are carbon, glass and basalt.

    The manufactured composite combinations are tested for reaction to fire EN 45545-2 and fire resistance EN 45545-3. The composites with the best fire-performance results are then further characterized for mechanical properties. A crucial property is the fatigue strength which is performed to harmonize with EN 12663-1 that is written with metals in mind. Several types of static tests are also performed.

    Another topic is adhesive joints for composites that also are investigated for fire performance and mechanical properties. Results Composites reaching higher hazard levels of EN 45545-2 are developed. For these are static strengths and SN-curves determined.

    Conclusions

    It is shown that composite material can be used for railway applications e.g. carbodyshell parts.

  • 209.
    Sandström, Johan
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Johannesson, Pär
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Mikael, Sidenmark
    Ocean Harvesting Technologies AB, Sweden.
    Reliability analysis with VMEA of a rack and pinion mechanism in a wave energy gravity accumulator2018Rapport (Annet vitenskapelig)
    Abstract [en]

    The method Variation and Mode Effect Analysis (VMEA) is successfully implemented for the AGMA based gear design of the rack pinion mechanism. The rack and pinion is a feature in Ocean Harvesting Technologies (OHT) gravity accumulator device. The purpose of it is to make the electrical power output to the grid more uniform. This is a novel technology where previous experience in designing is absent. The VMEA method is there for useful for incorporating all known uncertainties to estimate the uncertainty and reliability of the technology. This allows for adequate safety factors to be set so the desired reliability can be achieved.

    The uncertainty and reliability analysis is performed for different OHT designs and methods where the reliability is calculated. This calculation can be used as basis for further analysis when more design details are determined and modifications are made, thus allowing for more optimized and reliable design to be made.

  • 210.
    Schmid, Joachim
    et al.
    ETH Zürich, Switzerland.
    Brandon, Daniel
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Werther, Norman
    Technical University of Munich, Germany.
    Klippel, Michael
    ETH Zürich, Switzerland.
    Technical note - Thermal exposure of wood in standard fire resistance tests2019Inngår i: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226, Vol. 107, s. 179-185Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recently, standard fire resistance testing has been questioned for combustible products. A part of the comments address the thermal boundary conditions and the different thermal exposure of combustible products in comparison to incombustibles. These comments are evaluated in this technical note.To compare heat flux measurements of combustibles and incombustible products when tested in a furnace, furnace tests were performed. The furnace was controlled by plate thermometers to follow the EN 1363/ISO 834 standard temperature-time curve. It could be proven that (a) the heat flux measurements at the specimens surface behind the plate thermometer (PT) are not higher than in front of the PT. The reason for this is most likely that no flaming combustion is possible near the surface due to the low oxygen content typically for a furnace. It could be further shown (b) that the heat flux measurements when combustibles are tested follow the trend reported in literature for incombustibles. Further, (c) that the lower burner fuel used in furnaces is due to the contribution of the specimen (ca. 30% in the presented tests) and due to the lower thermal inertia (ca. 20% in the presented tests). Finally it can be concluded that the thermal exposure of combustibles and incombustibles is equivalent in furnaces simulating a ventilation controlled fire development for a pre-defined duration.

  • 211.
    Schmid, Joachim
    et al.
    ETH Zurich, Switzerland.
    Klippel, Michael
    ETH Zurich, Switzerland.
    Just, Alar
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety. Tallinn University of Technology, Estonia.
    Frangi, Andrea
    ETH Zurich, Switzerland.
    Tiso, Mattia
    Tallinn University of Technology, Estonia.
    Simulation of the Fire Resistance of Cross-laminated Timber (CLT)2018Inngår i: Fire technology, ISSN 0015-2684, E-ISSN 1572-8099, Vol. 54, nr 5, s. 1113-1148Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cross-laminated timber, typical abbreviations CLT or XLAM, is currently one of the most innovative product in building with wood. This solid engineered timber product provides advantages compared to other solid timber slabs as the dimension stability, i.e. swelling and shrinkage, is controlled by the crosswise laminations. As for other components, the fire resistance has to be verified for this type of product. While fire testing is time consuming and costly, simulations provide flexibility to optimize the product or to develop simplified design models for structural engineers. In this paper, a simulation technique is presented which can be used to determine the fire resistance of CLT. The technique was then used to develop simplified design equations to be used by engineers to predict the behavior of CLT in fire resistance tests and verify its fire resistance. Following existing models, the simplified design model aims for a two-step process whereby in a (i) first step the residual cross section and in (ii) a second step the load bearing capacity of the partly heated residual cross section is determined. The presented simulations consider the effective thermal–mechanical characteristics of wood exposed to standard fire and perform an advanced section analysis using a temperature profile corresponding to the actual protection and the location of the centroid together with the possibility of plasticity on the side of compression. It was shown that simulation results agree well with test results and that they can be used to determine layup specific modification factors used by the reduced properties method or zero-strength layers used by the effective cross section method. It was shown that the use of the zero-strength layers is favorable compared to the modification factors to calculate the resistance of the residual cross section. This is due to the large range of modification factors answering the typical layup of CLT comprising layers with their fiber direction cross the span direction. Subsequently, the methodology was used to determine design equations for initially unprotected and protected three-, five- and seven-layer CLT in bending and buckling. While the zero-strength layer for glulam beams in bending is assumed to be 7 mm (0.3 in), for CLT the corresponding value is in most of the cases between 5 mm and 12 mm but is different for other loading modes such as buckling (wall elements) and depending on the applied protection.

  • 212.
    Schmid, Joachim
    et al.
    ETH Zürich, Switzerland.
    Lange, David
    University of Queensland, Australia.
    Sjöström, Johan
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Brandon, Daniel
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Klippel, Michael
    ETH Zürich, Switzerland.
    Frangi, Andrea
    ETH Zürich, Switzerland.
    The use of furnace tests to describe real fires of timber structures2018Inngår i: WCTE 2018 - World Conference on Timber Engineering, World Conference on Timber Engineering (WCTE) , 2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Fire resistance is an important characteristic for all building structures regardless the building materials used. Methods for fire resistance testing were developed already before 1900 to measure the response of the structure in fire and compare different products. In the last decade, the increased popularity of timber buildings has led to a renewed interest in the performance of timber structures in fire and timber products were frequently tested in furnaces. Currently, some discussions question the validity of furnace test results for timber members which are carried out according to standards. Generally, it was stated that combustible and incombustible products are exposed to different thermal exposures when tested in furnaces or exposed in real fires. Additionally, some experts think that massive timber elements, e.g. cross-laminated timber (CLT), cannot be tested in furnaces as these products increase the fire load and, thus, statements in the framework of fire resistance testing are not possible. This paper investigates the validity of furnace resistance testing for combustible products and its limitations. It is shown that, firstly, the thermal exposure in fire resistance tests of incombustibles and combustibles is similar. Secondly, in addition to thermal exposure, the term fire exposure should be introduced where the oxygen concentration is described as the oxygen concentration significantly influences the behaviour of combustible material in fires. Thirdly, the furnace and compartment environment in flash-over fires is similar with respect to this fire exposure. Finally, it is not possible to directly use furnace test results to predict a compartment response in real fires including the cooling phase but recent investigations indicate that results from fire resistance tests can be used to predict burn-out when the mass loss of the timber specimen is measured.

  • 213.
    Schmid, Joachim
    et al.
    ETH Zurich, Switzerland.
    Santomaso, Alessandro
    Commissario Terza Corsia, Italy.
    Brandon, Daniel
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Wickström, Ulf
    Luleå University of Technology, Sweden.
    Frangi, Andrea
    ETH Zurich, Switzerland.
    Timber under real fire conditions - the influence of oxygen content and gas velocity on the charring behavior2018Inngår i: Journal of Structural Fire Engineering, ISSN 2040-2317, E-ISSN 2040-2325, Vol. 9, nr 3, s. 222-236Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose – The purpose of this study is to investigate the influencing factors on the charring behaviour of timber, the char layer and the charring depth in non-standard fires. Design/methodology/approach – This paper summarizes outcomes of tests, investigating the influences on the charring behavior of timber by varying the oxygen content and the gas velocity in the compartment. Results show that charring is depending on the fire compartment temperature, but results show further that at higher oxygen flow, char contraction was observed affecting the protective function of the char layer. Findings – In particular, in the cooling phase, char contraction should be considered which may have a significant impact on performance-based design using non-standard temperature fire curves where the complete fire history including the cooling phase has to be taken into account. Originality/value – Up to now, some research on non-standard fire exposed timber member has been performed, mainly based on standard fire resistance tests where boundary conditions as gas flow and oxygen content especially in the decay phase are not measured or documented. The approach presented in this paper is the first documented fire tests with timber documenting the data required.

  • 214.
    Sedlmayer, Irene
    et al.
    Vienna University of Technology, Austria; BIOENERGY 2020+ GmbH, Germany.
    Arshadi, Mehrdad
    SLU Swedish University of Agricultural Sciences, Sweden.
    Haslinger, Walter
    BIOENERGY 2020+ GmbH, Germany; Luleå University of Technology, Sweden.
    Hofbauer, Hermann
    Vienna university of Technology, Austria.
    Larsson, Ida
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Lönnermark, Anders
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Nilsson, Calle
    SLU Swedish University of Agricultural Sciences, Sweden.
    Pollex, Annett
    DBFZ Deutsches Biomasseforschungszentrum gemeinnützige GmbH, Germany.
    Schmidl, Christoph
    BIOENERGY 2020+ GmbH, Germany.
    Stelte, Wolfgang
    DTU Technical University of Denmark, Denmark.
    Wopienka, Elisabeth
    BIOENERGY 2020+ GmbH, Germany.
    Bauer-Emhofer, Waltraud
    BIOENERGY 2020+ GmbH, Germany; Vienna University of Technology, Austria.
    Determination of off-gassing and self-heating potential of wood pellets – Method comparison and correlation analysis2018Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 234, s. 894-903Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several methods for identifying the phenomena of self-heating and off-gassing during production, transportation and storage of wood pellets have been developed in recent years. Research focused on the exploration of the underlying mechanisms, influencing factors or the quantification of self-heating or off-gassing tendencies. The present study aims at identifying a clear correlation between self-heating and off-gassing. Thus, different methods for determining self-heating and off-gassing potentials of wood pellets are compared. Therefore, eleven wood pellet batches from the European market were analyzed. For this investigation, three methods for the determination of self-heating, like isothermal calorimetry, oxi-press and thermogravimetric analysis, and four methods for off-gassing, like volatile organic compound (VOC) emissions measurements, gas phase analysis of stored pellets in a closed container by offline and by glass flask method and determination of fatty and resin acids content, were performed. Results were ranked according to the self-heating and off-gassing tendency providing a common overview of the analyzed pellets batches. Relations between different methods were investigated by Spearman's correlation coefficient. Evaluation of the results revealed an equal suitability of offline and glass flask methods to predict off-gassing tendency and indicated a very significant correlation with isothermal calorimetry for the identification of self-heating tendency. The thermogravimetric analysis as well as the fatty and resin acids determination proved to be insufficient for the exclusive assessment of self-heating and off-gassing tendency, respectively.

  • 215.
    Shu, J.
    et al.
    Zhejiang University, China; Chalmers University of Technology, Sweden.
    Honfi, Daniel
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Plos, M.
    Chalmers University of Technology, Sweden.
    Zandi, K.
    Chalmers University of Technology, Sweden.
    Magnusson, J.
    NCC Sverige AB, Sweden.
    Assessment of a cantilever bridge deck slab using multi-level assessment strategy and decision support framework2019Inngår i: Engineering structures, ISSN 0141-0296, E-ISSN 1873-7323, Vol. 200, artikkel-id 109666Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A Multi-Level Assessment Strategy has previously been proposed and proved feasible for structural analysis of existing RC slabs. In this paper, the Multi-Level Assessment Strategy, which focuses on sophisticated structural analysis, was used to investigate the load-carrying capacity and structural behaviour of a composite bridge with an RC bridge deck slab subjected to a concentrated load. In addition to more sophisticated structural analysis, improved knowledge content about the structure and more advanced models for uncertainty consideration were also incorporated in a systematic way for higher levels of assessment. Furthermore, a decision support system was adopted, in which the cost for different alternatives regarding if and how the assessment should be enhanced with respect to model sophistication, knowledge content and modelling uncertainty were compared in a systematic way. The results show not only that the load-carrying capacity and the structural behaviour can be assessed with different level of detailing, but also that the cost for each level of assessment can be evaluated with a decision support system, facilitating more sustainable management of infrastructure. 

  • 216.
    Sjöström, J.
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Lange, David
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Jansson Mcnamee, Robert
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Boström, Lars
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Anisotropic Curvature and Damage of Unbonded Post-tensioned Concrete Slabs During Fire Testing2017Inngår i: Fire technology, ISSN 0015-2684, E-ISSN 1572-8099, Vol. 53, nr 3, s. 1333-1351Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Two furnace tests, using two different fire exposures, on unbonded post-tensioned concrete slabs (1700 × 1200 mm) are reported. Local curvature is measured along two lines approximately in the middle of the slabs both parallel (longitudinal) and orthogonal (transverse) to the prestressing direction. More pronounced curvature in the transverse direction is accompanied by the formation of cracks running predominantly in the longitudinal direction. While the transverse curvature relaxes back to the original state after the cooling phase the curvature in the longitudinal direction ultimately exhibits upward deflection due to the hogging moment caused by the prestress in the tendons acting on a cross section with temperature reduced mechanical properties at the fire exposed side. The effect on crack formation due to the prestressing can additionally be detected by ultrasonic pulse velocity measurements in the different directions through the depth of the slab, where a reduction of 5–25% is observed in the transverse direction compared to the longitudinal direction. The phenomenological mechanical behaviour of the slabs is captured in a finite element model which describes the evolution of stress in the prestressing tendons. This model additionally suggests that the curvature in the transverse direction is independent of the prestressing in the longitudinal direction. © 2016 Springer Science+Business Media New York

  • 217.
    Sjöström, Johan
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Plathner, Frida
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Granström, Anders
    SLU Swedish University of Agricultural Sciences, Sweden.
    Wildfire ignition from forestry machines in boreal Sweden2019Inngår i: International journal of wildland fire, ISSN 1049-8001, E-ISSN 1448-5516, Vol. 28, nr 9, s. 666-677Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Several large Swedish wildfires during recent decades were caused by forestry machinery in operation, fires for which there is still no characterisation. We combined 18 years of data on dispatches, weather and fire danger and interviewed forestry workers to understand the spatial, temporal and weather distributions of these fires, and their underlying mechanisms. We estimate the average annual number of ignitions from forestry machinery in Sweden at 330-480 (2.0 ± 0.4 ignitions per 1000 ha clear-felling) of which 34.5 led to firefighter dispatches, constituting 2.2% of all forest fire dispatches and 40% of area burnt. Soil scarification causes the most ignitions and the main mechanism is likely high-inertia contact between discs and large stones, causing sparks igniting dry humus or moss, countering reports suggesting that such metal fragments cannot fulfil ignition requirements. We found a spatial relationship between forestry machine ignitions and abundance of large stones, represented by a Boulder Index generated from a nationwide dataset. Further, 75% of the dispatches occurred on days with relative humidity <45%, Duff Moisture Code (Canadian system) >26 and Fire Weather Index >12. 75% of the area burned when Fire Weather Index was >20. Results suggest machine-caused forest fires can be largely avoided by cancelling operations in stony terrain during high-risk weather.

  • 218.
    Sjöström, Johan
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Vermina Lundström, Frida
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Granström, Anders
    SLU Swedish University of Agricultural Sciences, Sweden.
    Skogsbränder orsakade av skogsmaskiner2018Rapport (Annet vitenskapelig)
    Abstract [en]

    Several large wildfires in Sweden are caused by forestry machinery in operation, but there is no overview or characterization of machine-caused fires. Combining dispatch data, weather, fire danger and interviews with forestry entrepreneurs we gain a deeper understanding of spatial/temporal/weather distributions of these fires as well as their characteristics and underlying mechanisms. The average annual number of machine-caused ignitions in Sweden is estimated to 330-480 (2.0±0.4 ignitions per 1000 ha clear-felled land) of which 34.5 lead to fire-fighter dispatch. These constitute 2.2% of all forest fires and 40% of area burnt. Soil scarification causes most ignitions and the main mechanism is likely high-inertia contact between discs and large stones, causing sparks igniting dry humus/moss. This counters reports suggesting that such metal fragments cannot fulfil ignition requirements. We found a strong spatial relationship between forestry machinery ignitions and the abundance of large stones, represented by a boulder-index generated from 13500 nation-wide site inventories. Further, 75% of the dispatches occurred on days with relative humidity <45%, Duff Moisture Code >26 and Fire Weather Index >12. 75% of the total area burned when Fire Weather Index >20. Cancelling operations in stony terrain during high-risk weather situations can largely avoid the problem.

  • 219.
    Sterley, Magdalena
    et al.
    RISE - Research Institutes of Sweden, Bioekonomi, Biobaserade material.
    Noren, Joakim
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Byggteknik.
    Liblik, Johanna
    Tallinn University of Technology, Estonia.
    Brandon, Daniel
    Just, Alar
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety. Tallinn University of Technology, Estonia.
    Small-scale test method for the fire behaviour of woodadhesive bonds in CLT2018Inngår i: Book of abstracts of the final conference COST FP1404”Fire Safe Use of Bio-Based Building Products”, 2018Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    There is an increasing use of cross laminated timber (CLT) in the building sector. CLT is a wood panel product made from layers of solid lumber boards. Each layer of boards is oriented perpendicular to adjacent layers and glued on the wide faces of each board. It has been recognised that different adhesive systems have different behaviour in fire; especially that delamination behaviour of CLT can be avoided by choosing a suitable adhesive system. The best method for evaluation of the delamination is a full‐scale fire test, but considering the high costs of such tests, it is of the utmost importance to develop small‐scale methods for evaluating the adhesive bond properties in fire. The intention is that such small‐scale methods should provide the same results as full‐scale tests. A new, smaller scale method for classifying adhesives with respect to  fire properties would also simplify  the planning of  full scale  tests. Previous  tested small‐scale method for evaluation of finger joints is presented in (1).  In this study, a small‐scale fire test methodology for evaluation of CLT adhesive bond performance in  fire  is  introduced  (2).  The  aim  was  to  demonstrate  an  easy  tool  to  distinguish  between  fire resistant adhesive bonds and non‐fire‐resistant bonds, especially with respect to delamination. The cone heater of a cone calorimeter was used to carry out the tests. Cone calorimeter in accordance with ISO 5660 is one of the most widely used bench‐scale instrument in fire research. This small‐scale  device  has  several  advantages  over  larger‐scale  tests  thanks  to  its  fast,  simple  and  cost‐efficient manner to investigate basic material properties.  

  • 220.
    Storesund, Karolina
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Amon, Francine
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Shayesteh, Haghighatpanah
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Steen-Hansen, Anne
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Larsson, Ida
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Bergstrand, Anna
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Fire safe furniture in a sustainable perspective2019Rapport (Annet vitenskapelig)
    Abstract [en]

    Loose furnishings, such as upholstered furniture, mattresses and textiles, are very important for the early stages of fires. Such products can be easily ignited, contribute to rapid spread of fire and produce a lot of smoke and heat when they burn. This limits the time and opportunity for evacuation and fire rescue. The regulation of fire properties of interior textiles, armchairs, sofas and mattresses has been discussed nationally and internationally for many years, without resulting in more stringent requirements for such products, at least not on a harmonized level. Fire safety and environmental considerations are important factors that are often set against each other. It is therefore important to promote the development of safe and fireproof furnishings that are environmentally friendly throughout their life cycle, and which satisfy other requirements that are usually imposed on this product group. The main objective of this project has been to contribute to new knowledge about how fire safety associated with loose interior design can be improved through developing products that meet sustainability and circularity requirements. These new products shall have fire performance comparable to flame retarded reference products but will rely on construction techniques and materials containing small amounts or no flame retardants. The new products shall be safe while in use and shall be recyclable at the end of life. Sustainability and environmental impact analyses including life cycle analyses of furnishing materials have been performed, as well as fire tests for screening the fire performance of a selection of material combinations. Combining a requirement for both sustainable yet fire safe furnishing is a complex task to solve. The more complex the material combination, the more difficult to predict both factors in parallel. Slight variations in components can potentially change the overall scoring of their performance. Cotton, wool and polyester has been shown to have equally high sustainability scores, although cotton had relatively high environmental impact. Polyamide was identified as the fabric with the best environmental performer but scoring lower on sustainability. The cushion material has great impact on fire safety because it may contribute with large amounts of heat energy and smoke. Polyurethane is by far the most common cushion material and comes in many variations, some including chemical fire retardants (FR). FR’s have not been included in in the sustainability and environmental impact analyses in this study, instead focus has been on exploring alternative methods of achieving comparable fire performance. In the case of cushion material, latex was identified as performing much higher on both sustainability and environmental impact than polyurethane. Unfortunately, latex was not a part of the fire testing series and was therefore not explored with regard to fire performance. Future studies should explore the interaction of the fire performance properties of different materials identified as high sustainability and environmental impact performers, especially in full scale room fire experiments. Thorough knowledge about how different components (of high sustainability and low environmental impact) contribute to the fire performance and how these are maintained throughout the furniture’s lifetime, would improve the possibility of fire safe furniture to be part of a circular economy.

  • 221.
    Storesund, Karolina
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Reitan, Nina Kristine
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Sjöström, Johan
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Rød, B.
    UiT The Arctic University of Norway, Norway.
    Guay, F.
    INOV INESC Inovação, Portugal.
    Almeida, R.
    Danish Institute of Fire and Security Technology, Denmark.
    Theocharidou, M.
    European Commission, Italy.
    Novel methodologies for analysing critical infrastructure resilience2018Inngår i: Safety and Reliability - Safe Societies in a Changing World - Proceedings of the 28th International European Safety and Reliability Conference, ESREL 2018, 2018, s. 1221-1230Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In the field of Critical Infrastructures (CI), both policy and research focus has shifted from protection to resilience. The IMPROVER project has developed a CI resilience management framework (ICI-REF), applicable to all types of CI and resilience domains (technological, organisational and societal) allowing operators to understand and improve their resilience. IMPROVER has also developed methodologies to be used within the framework, accompanied with resilience indicators for operators to assess their technological and organisational resilience. The framework allows CI operators to incorporate resilience management as part of their risk management processes. The ICI-REF, the resilience analysis methodologies and indicators have been optimised, applied and demonstrated in a pilot implementation, focusing on the potable water supply in Barreiro, Portugal. Conclusions from the operators so far are that the indicators, well-defined and unambiguously described, are crucial for monitoring resilience activities, to ensure objective, consistent, repeatable and representative results from the assessed processes.

  • 222.
    Storesund, Karolina
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Steen-Hansen, Anne
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Amon, Francine
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Haghighatpanah, Shayesteh
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Larsson, Ida
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Fire safe, sustainable loose furnishing2019Inngår i: Interflam 2019: Conference Proceedings, 2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this study has been to investigate the fire properties and environmental aspects of different upholstery material combinations. An analysis of the sustainability and circularity of selected textiles, along with lifecycle assessment, is used to qualitatively evaluate materials from an environmental perspective. The cone calorimeter was the primary tool used to screen 20 different material combinations from a fire performance perspective. It was found that textile covers of conventional fibres such as wool, cotton and polyester, can be improved by blending them with fire resistant speciality fibres. A new three-dimensional web structure has been examined, showing preliminary promising fire properties with regard to ignition time, heat release rates and smoke production.

  • 223.
    Storesund, Karolina
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Steen-Hansen, Anne
    RISE - Research Institutes of Sweden, Säkerhet och transport, Fire Research Norge.
    Bergstrand, Anna
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Fire safe upholstered furniture: Alternative strategies to the use of chemical flame retardants2015Rapport (Annet vitenskapelig)
    Abstract [en]

    It is well known that upholstered furniture represents a fire risk due to the fact that it is composed of relatively large amounts of easily ignited and very combustible materials. The fire properties are usually improved by adding chemical flame retardants to the upholstery materials.

    The goal of this investigation is to demonstrate how sufficient fire safety in upholstered furniture may be achieved, without the use of flame retardant chemicals.

    A number of cover materials in different combinations with other materials including wadding, barrier materials and foam, have been tested in small scale cone calorimeter tests and in mock-up chair tests. Time to ignition, heat release and smoke production of the different combinations have been examined.

    It is shown that there certainly are possibility to improve these properties by means of alternative strategies other than by adding chemical flame retardants.

  • 224.
    Strömgren, Michael
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Nordic Fire Safety Engineering and Tall Buildings in Sweden2017Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 225.
    Sturk, David
    et al.
    Autoliv Sverige AB, Sweden.
    Rosell, Lars
    RISE - Research Institutes of Sweden, Biovetenskap och material, Kemi och material.
    Blomqvist, Per
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Ahlberg Tidblad, Annika
    Volvo Car Corporation, Sweden.
    Analysis of li-ion battery gases vented in an inert atmosphere thermal test chamber2019Inngår i: Batteries, ISSN 2313-0105, Vol. 5, nr 3, artikkel-id 61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One way to support the development of new safety practices in testing and field failure situations of electric vehicles and their lithium-ion (Li-ion) traction batteries is to conduct studies simulating plausible incident scenarios. This paper focuses on risks and hazards associated with venting of gaseous species formed by thermal decomposition reactions of the electrolyte and electrode materials during thermal runaway of the cell. A test set-up for qualitative and quantitative measurements of both major and minor gas species in the vented emissions from Li-ion batteries is described. The objective of the study is to measure gas emissions in the absence of flames, since gassing can occur without subsequent fire. Test results regarding gas emission rates, total gas emission volumes, and amounts of hydrogen fluoride (HF) and CO2 formed in inert atmosphere when heating lithium iron phosphate (LFP) and lithium nickel-manganese-cobalt (NMC) dioxide/lithium manganese oxide (LMO) spinel cell stacks are presented and discussed. Important test findings include the large difference in total gas emissions from NMC/LMO cells compared to LFP, 780 L kg−1 battery cells, and 42 L kg−1 battery cells, respectively. However, there was no significant difference in the total amount of HF formed for both cell types, suggesting that LFP releases higher concentrations of HF than NMC/LMO cells. © 2019 by the authors.

  • 226.
    Vermina Lundström, Frida
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Andersson, Petra
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Faktorer som påverkar en bostadsbrands storlek – analys av försäkringsbolagens data2018Rapport (Annet vitenskapelig)
    Abstract [en]

    Every year, the insurance sector reports 23 000 fire incidents in Sweden. Of these, the fire rescue service are called into 6 000. Since there is little knowledge on the fires that the fire rescue service is not involved in, incident data from insurance companies has been analyzed.

    One limitation to the results in this report is that the insurance sector’s definition of fire is broad; e.g. short-circuit is regarded a fire incident.

    Still, the data complies with the statistics from the fire rescue service: Kitchen fires and fire in electric equipment are the most common sources of fire in residential buildings.

    The cost (property damage) of a fire is also presented. It is seen that the most common fires sources commonly lead to a relatively low economical loss.

  • 227.
    Vermina Lundström, Frida
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Larsson, Ida
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Bergstrand, Anna
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Strömgren, Michael
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Förändringar och trenders påverkan på brandsäkerheten i bostäder2018Rapport (Annet vitenskapelig)
    Abstract [sv]

    År 2009 antog Myndigheten för samhällskydd och beredskap (MSB) en nationell strategi för dödsbränder. Denna syftade till att ingen skulle omkomma eller skadas allvarligt till följd av brand i Sverige - en s.k. nollvision. Årligen dör nästan hundra personer av brandrelaterade skador i Sverige och antalet omkomna har under senare år hållit sig relativt konstant även om det har minskat över en längre tid.

    Risken för att omkomma i brand utgår ifrån individens förutsättningar och levnadsförhållanden. Dessa förutsättningar påverkas till viss del av trendskiftningar i samhället. Denna rapport syftar till att identifiera och analysera trender som har en påverkan på individens risk för att dö till följd av brand. Rapporten syftar också till att identifiera vilka trender som det inte har forskats tillräckligt på för att kunna dra några slutsatser om dödsbrandsrisken. Slutligen ges en framtidsutsikt för trender där en sådan kan skönjas.

    Vad gäller detektion och släckning har mycket forskning tillägnats brandvarnare. Nya smarta system har införts på marknaden de senaste åren. Dessa har potential att förbättra brandsäkerheten, men mer forskning behövs. Detta gäller även andra system (utom brandvarnare); mer forskning behövs för att kunna visa en signifikant positiv effekt.

    En hel del forskning existerar vad gäller prediktion av brand i olika typer av byggnadsmaterial. Samtidigt införs nya och ”nygamla” material på bostadsmarknaden och bostäderna blir ”tätare” mot brand pga. t.ex. flerglasfönster och mer isolering. Nya bostäder tenderar också att byggas med öppnare planlösning än för 30 år sedan, även om bostadsytan i snitt per person inte har ändrats de senaste åren. Detta medför en ökad risk för snabb brand- och rökspridning inom brandcellen, men brännbara byggnadsmaterial kan också medföra ökad brandspridning utanför brandcellen om byggnadsregler inte efterföljs.

    Det finns en del kunskap om samhällets funktioner och tjänster, såsom sjukvård efter brand, räddningstjänst mm. men effektivitet och trendskiftningar är svåra att mäta.

    Olika individer löper olika stor risk att dö i brand beroende på t.ex. ekonomisk situation, ålder och livsstil. Vad gäller livsstil har antalet rökare i varje åldersgrupp stabiliserats något sedan nedgången efter rökförbudet på uteserveringar infördes år 2005. Däremot ökar alkoholkonsumtionen. Både antalet ensamboende och antalet trångbodda ökar, där båda grupperna har en förhöjd dödsbrandsrisk. Fler äldre med vårdbehov förutspås bo kvar i sina hem i framtiden. Äldre utgör en särskilt utsatt grupp vad gäller dödsbrand och därför bör riktade insatser göras vad gäller denna grupp för att uppfylla MSB:s nollvision.

  • 228.
    Vermina Lundström, Frida
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety. Lund University, Sweden.
    Quintiere, James G.
    University of Maryland, USA.
    van Hees, Patrick
    Lund University, Sweden.
    Analysis of extinction and sustained ignition2019Inngår i: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226, Vol. 105, s. 51-61Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The limiting conditions for sustained burning of materials are studied experimentally using gas burners. Small pool fire configurations are examined to determine the mass flux for a sustained surface diffusion flame (fire point) and the subsequent extinction limit of that flame. The burner results are compared to material data for sustained ignition, and are found to be lower. Material reported values of a critical mass flux are disparate, and burner data show that the critical mass flux can range from about 1 to 50 g/m2s. Previous studies have indicated the results depend on the convective heat transfer coefficient and the heat of combustion of the gases, but until this work no study has been presented to systematically show these dependencies. Three porous gas burners of diameters 25, 50 and 100 mm were used with fuel gases including methane, propane, isobutene, and ethylene mixed with nitrogen to precisely change the mixture heat of combustion. Diffusion flame theory based on a critical flame temperature at extinction is used to explain and correlate data for both limits. It was found that there is no statistical difference between the sustained ignition and extinction limits. A correlation for the critical mass flux is produced with heat of combustion and fuel diameter as sole dependent variables for all the fuels except methane. The results show that no burning is possible below a heat of combustion of 3–4 kJ/g. This is consistent with the European classification system for non-combustibility where the corresponding limit is set at 2 kJ/g.

  • 229.
    Vermina Lundström, Frida
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Sjöström, Johan
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Lärdomar från inträffade vegetations-bränder under vinterhalvåret2017Rapport (Annet vitenskapelig)
    Abstract [en]

    Although wildland fires are not common during the cold season in the Nordic countries, there is a risk for uncontrolled spread. This was proved during a mild winter in Norway in 2014, when three large fires occurred. Therefore, a fire weather forecast running during winter time could provide the rescue service with knowledge on the risk of spreading fires. In this report, data from previous fires is gathered to gain knowledge on how to modify a risk index for fire weather during the Swedish winter.

  • 230.
    Vermina Plathner, Frida
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety. Lund University, Sweden.
    Hees, Patrick
    Lund University, Sweden.
    Experimental assessment of bench-scale ignitability parameters2019Inngår i: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 43, nr 2, s. 123-130Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Summary This work aims to explore possible ways of improving the precision of ignition measurements in the cone calorimeter. Both inherent repeatability of parts of the testing equipment and operator-dependent variations are considered. Inherent repeatability is indicated to be slightly improved if the test samples used are circular rather than square. Operator-dependent variation is discussed in terms of the method used for determining ignition. Four procedures are compared, namely, visual observation, usage of a light sensor, and looking at the peak of the second and first derivatives of the mass loss and heat release curves, respectively. Results indicate that the preferable operator-independent method depends on the test conditions; the derivative of the heat release rate is an alternative to the mass loss rate derivative when the scale is of standardised quality. A light sensor for ignition time observation is a good option when the surrounding light is not changed during the test.

  • 231.
    Vylund, Lotta
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Gehandler, Jonathan
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport.
    Karlsson, Peter
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Peraic, Klara
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Huang, Chen
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Evergren, Franz
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Fire-fighting of alternative fuel vehicles in ro-ro spaces2019Rapport (Annet vitenskapelig)
    Abstract [en]

    Fire in alternative fuel vehicles in ro-ro spaces (BREND)

    A literature study has been carried out that compiles the body of research regarding hazards related to fire in alternative fuel vehicles (AFV) in ro-ro spaces. Alternative fuels include liquefied gas (e.g. LNG), compressed gas (e.g. CNG) and batteries. Hazards related to a conventional vehicle on fire are heat, smoke and toxic gases. Another hazard is projectiles related to small explosions of e.g. tyres or airbags. AFVs also include hazards of large explosion, jet flames, more apparent re-ignition, etc.

    The study also includes land based fire fighting tactics related to AFV fires. If the fuel storage on an AFV is affected, land-based firefighters often use a defensive tactic, which means securing the area around the vehicle and preventing fire propagation from a distance. This tactic has been evaluated in the context of a ro-ro space and the results are compiled in a test report (Vylund et al 2019). The project has resulted in guidelines on how to handle AFV fires in roro spaces (see appendix 1).

  • 232.
    Vylund, Lotta
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Mindykowski, Pierrick
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Palmkvist, Krister
    RISE - Research Institutes of Sweden (2017-2019), Säkerhet och transport, Safety.
    Methods and equipment for fire fighting with alternative fuel vehicles in ro-ro spaces2019Rapport (Annet vitenskapelig)
    Abstract [en]

    RISE Research Institutes of Sweden have carried out fire tests to evaluate fire fighting methods in case of a fire involving alternative fuel vehicles (AFV) in a ro-ro space. This report presents how selected fire fighting methods were practically evaluated for their possible to use in ro-ro spaces. The results can be applied for safer and more efficient manual fire fighting operations, which is increasingly important when carrying AFVs.

    The fire tests were performed in a large fire test hall at RISE Fire Research in Borås and the fire load was represented by a steel mock-up of a personal vehicle with a propane test rig, creating a fire of 4 MW. Steel walls, representing adjacent vehicles, were fitted with thermocouples to measure the temperature 0.6 m from the mock-up vehicle. Extinguishing media were applied between the mock-up and the steel wall on the left-hand of the vehicle and the temperature reduction was measured. The results present the reduction coefficient achieved by different systems, i.e. the heat blockage effect achieved by the systems. A high reduction coefficient indicates that the system has a high capacity to reduce heat exposure and prevent fire spread to an adjacent vehicle.

    For handheld system, the highest reduction coefficient was achieved by the Industrial system and the FRS system (but only with a high water flow rate), providing both a reduction coefficient of 0.64. Reduction coefficient on the opposite side of the vehicle, from where the water was applied, also varied between the different systems. The highest reduction coefficient on this side was achieved by the high pressure 60 system, providing a reduction coefficient of 0.34. For water curtain system the Hose provided the highest capacity to reduce heat exposure on both side of the vehicle.

    How different tactical options could optimize the performance of the handheld systems was evaluated primarily by visual observations. After the first part of the test was conducted (measuring blockage effects) the operator was able to oscillate the water spray, both up and down and over the vehicle. The operator also approached the vehicle from the front, at an angel of 45°, in order to observe the effects with respect to cooling or suppression. By varying the technique, it was possible to optimize the cooling effect on both sides of the vehicle, but the operator must be able to adjust cone angle and water spray pattern to maximize the effect. During this part of the tests it was possible to observe that some systems had a limitation in capacity with respect to cooling or suppression, especially if the pressure was low or if it had a low water flow rate. The water curtain systems were not able to affect the other side of the vehicle, which indicates the need of positioning the nozzle or hose on at least two sides of the burning vehicle to be able to efficiently prevent fire spread.

    A field test (outdoor) was also conducted to evaluate the practical usability of the tested systems. A simulated ro-ro space was built up on a fire rescue training field where relevant crew tried different tactical options with the different system. It was found that a semi-rigid hose with a small inner diameter is much easier to handle in most cases but must be compared with desired capacity of pressure, water flow rate and throw length. A hose with a larger inner diameter will have greater stiffness which proved to be useful when trying to position water curtain nozzles. The tests showed that it is possible to position water curtain nozzles to prevent fire spread, but the hose most be further developed to be able to use in ro-ro spaces.

  • 233.
    Vylund, Lotta
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Palmkvist, Krister
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Taktik och metodik för släckning av höga trähus2017Rapport (Annet vitenskapelig)
    Abstract [en]

    Different extinguishment strategies for fires in cavities in tall timber buildings are presented together with their effectiveness and possibility to minimize water damages. In addition are exercises suggested to give training in how to extinguish fires in cavities in tall timber buildings.

    Tall timber buildings are well fire protected today, but wood is a combustible material and the spread of fire to cavities sometimes occur. The first action when there is a hidden fire in a cavity is to identify the structure of the building. Infrared (IR) cameras are a good tool for identifying the building structure and indicate the location of the fire. However, it is important to have a good basic training of using the camera in order to correctly interpret the IR images.

    The most important thing during the extinguishing work is to avoid opening up the cavities and thereby add oxygen to the fire before the fire is under control. Extinguishing media must therefore be applied through small openings. Tests have shown that, among water-based extinguishing media, the cutter extinguisher is the most efficient for fires in cavity with the least water supply. Potential other extinguishing agents are nitrogen or carbon dioxide, but techniques and tactics when using these extinguishing media must be further developed. The main drawback of these media is the limited cooling capabilities of the surfaces and gas volume.

  • 234.
    Wallqvist, Viveca
    et al.
    RISE - Research Institutes of Sweden, Biovetenskap och material, Kemi och material.
    Kjell, G.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Cupina, Ena
    RISE - Research Institutes of Sweden, Biovetenskap och material, Kemi och material. Chalmers Univeristy of technology, Sweden.
    Kraft, Lars
    RISE - Research Institutes of Sweden, Samhällsbyggnad, CBI Betonginstitutet.
    Deck, C.
    University of Strasbourg, France.
    Willinger, R.
    University of Strasbourg, France.
    New functional pavements for pedestrians and cyclists2017Inngår i: Accident Analysis and Prevention, ISSN 0001-4575, E-ISSN 1879-2057, Vol. 105, s. 52-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    When many fields of pedestrian and cyclist safety have been extensively studied, the surfacing has long been left unquestioned, despite being developed for another mode of transport and being one of the main causes for falls and fall injuries. In this project new surfacing materials for pedestrian and cyclist safety have been produced. Focusing on augmenting previously largely disregarded parameters as impact absorption, comfort and visibility at the same time as avoiding deteriorating of crucial parameters as friction and wear resistance. Rubber content, binder type, and pigment addition have been varied and evaluated. The results demonstrate that by increasing rubber content of the mixtures the head injury criterion (HIC) value and injury risk can be decreased while maintaining frictional properties according to existing criteria. Assembly of test-lanes demonstrate that some developed materials experience lower flow and component separation than standard materials due to rubber addition, calling for further optimisation of construction procedure linked to content development. Initial trials on the test-lanes indicate that a polyurethane (PU) based material has high cycling comfort, visibility and can be modified with phosphorescence properties. For standard asphalt, impact absorption might be inflicted by modification of bitumen alone but is mostly augmented by rubber addition. The results also indicate that rubber content can decrease ice formation on the materials.

  • 235.
    Wang, Shule
    et al.
    KTH Royal Institute of Technology, Sweden.
    Persson, Henry
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety. KTH Royal Institute of Technology, Sweden.
    Yang, Weihong
    KTH Royal Institute of Technology, Sweden.
    Jönsson, Pär
    KTH Royal Institute of Technology, Sweden.
    Pyrolysis study of hydrothermal carbonization-treated digested sewage sludge using a Py-GC/MS and a bench-scale pyrolyzer2019Inngår i: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 262, artikkel-id 116335Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The disposal of digested sewage sludge is becoming a global problem. Hydrothermal carbonization (HTC) combined with the pyrolysis of digested sewage sludge was investigated by using a new conversion route for the exploitation of sewage sludge in energy applications. The thermochemical properties of the material were investigated by using HTC pre-treatments, thermogravimetric analyses, pyrolysis tests in Py-GC/MS and a bench-scale fixed bed reactor at temperatures of 450, 550, and 650 °C. It was found that the thermal decomposition of the hydrothermally treated digested sewage sludge takes place in a two-stage reaction. After pyrolysis, the ash in the sample was oxidized in the O2 atmosphere at 900 °C. Therefore, a new characterization method for determination of the non-oxdized ash content and fixed carbon content was proposed. The result from Py-GC/MS shows that the abundance of aromatic hydrocarbons in pyrolytic vapors present a positive correlation with increased temperature. In the bench-scale experiments, the highest HHV of the organic fraction was obtained at 650 °C as 38.46 MJ/kg. 

  • 236.
    Wendt, F.
    et al.
    National Renewable Energy Laboratory, US.
    Eskilsson, Claes
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety. Aalborg University, Denmark.
    Yasutaka, I.
    Saga University, Japan.
    Ocean energy systemswave energy modelling task: Modelling, verification and validation ofwave energy converters2019Inngår i: Journal of Marine Science and Engineering, E-ISSN 2077-1312, Vol. 7, nr 11, artikkel-id 379Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The International Energy Agency Technology Collaboration Programme for Ocean Energy Systems (OES) initiated the OES Wave Energy Conversion Modelling Task, which focused on the verification and validation of numerical models for simulating wave energy converters (WECs). The long-term goal is to assess the accuracy of and establish confidence in the use of numerical models used in design as well as power performance assessment of WECs. To establish this confidence, the authors used different existing computational modelling tools to simulate given tasks to identify uncertainties related to simulation methodologies: (i) linear potential flow methods; (ii) weakly nonlinear Froude-Krylov methods; and (iii) fully nonlinear methods (fully nonlinear potential flow and Navier-Stokes models). This article summarizes the code-to-code task and code-to-experiment task that have been performed so far in this project, with a focus on investigating the impact of different levels of nonlinearities in the numerical models. Two different WECs were studied and simulated. The first was a heaving semi-submerged sphere, where free-decay tests and both regular and irregular wave cases were investigated in a code-to-code comparison. The second case was a heaving float corresponding to a physical model tested in a wave tank. We considered radiation, diffraction, and regular wave cases and compared quantities, such as the WEC motion, power output and hydrodynamic loading.

  • 237.
    Wickström, Ulf
    et al.
    Luleå University of Technology, Sweden.
    Anderson, Johan
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Sjöström, Johan
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Measuring incident heat flux and adiabatic surface temperature with plate thermometers in ambient and high temperatures2019Inngår i: Fire and Materials, ISSN 0308-0501, E-ISSN 1099-1018, Vol. 43, nr 1, s. 51-56, artikkel-id 2667Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new more insulated and faster responding plate thermometer (PT) is introduced,which has been developed for measurements particularly in air at ambient temperature.It is a cheaper and more practical alternative to water‐cooled heat flux meters(HFMs). The theory and use of PTs measuring incident radiation heat flux and adiabaticsurface temperature are presented. Comparisons of measurements with PTsand HFMs are made. Finally, it is concluded that incident radiation in ambient aircan be measured with HFMs as well as with the new insulated type of PT. In hot gasesand flames, however, only PTs can be recommended. At elevated gas temperatures,convection makes measurements with HFMs difficult to interpret and use for calculations.However, they can be used in standard or well‐defined configurations forcomparisons.

  • 238.
    Widlund, Ola
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Snygg, Henrik
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Johnson, Erland
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Load classification of scaffolding systems: Using numerical modelling to show compliance with regulatory requirements2017Inngår i: Proceedings of NAFEMS World Congress 2017, Stockholm 11-14 June 2017, Stockholm, Sweden., 2017Konferansepaper (Fagfellevurdert)
  • 239.
    Wikman, Johan
    et al.
    RISE - Research Institutes of Sweden.
    Evegren, Franz
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Rahm, Michael
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Leroux, Jerome
    Bureau Veritas, France.
    Breuillard, Antoine
    Bureau Veritas, France.
    Kjellberg, Mattias
    Stena AB, Sweden.
    Gustin, Lisa
    Stena AB, Sweden.
    Efraimsson, Fredrik
    Stena AB, Sweden.
    Study investigating cost effective measures for reducing the risk from fires on ro-ro passenger ships (FIRESAFE): Appendix: Sensitivity and Uncertainty Analyses2017Rapport (Annet vitenskapelig)
  • 240.
    Wikman, Johan
    et al.
    RISE - Research Institutes of Sweden.
    Evegren, Franz
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Rahm, Michael
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Leroux, Jerome
    Bureau Veritas, France.
    Breuillard, Antoine
    Bureau Veritas, France.
    Kjellberg, Mattias
    Stena Rederi AB, Sweden.
    Gustin, Lisa
    Stena Rederi AB, Sweden.
    Efraimsson, Fredrik
    Stena Rederi AB, Sweden.
    Breuillard, Antoine
    Bureau Veritas, France.
    Study investigating cost effective measures for reducing the risk from fires on ro-ro passenger ships (FIRESAFE)2017Rapport (Annet vitenskapelig)
  • 241.
    Williams Portal, Natalie
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Boubitsas, Dimitrios
    RISE - Research Institutes of Sweden, Samhällsbyggnad, CBI Betonginstitutet.
    Sprickor i betong2019Rapport (Annet vitenskapelig)
    Abstract [en]

    The Swedish Fortifications Agency’s (FORTV) property stock consists of numerous concrete structures built both above and below rock. Some of these structures have experienced cracking overtime which, in turn, can lead to subsequent problems such as reinforcement corrosion and deterioration of structural performance. Due to the fact that in many cases there are building requirements related to protection against forced entry and weapon attacks, it is of great importance for FORTV to gain an understanding of how cracks are developed, the significance of the crack development, how do cracks affect the performance, as well as how cracks can be remediated. A similar project, with a focus on so-called access protection, has earlier been managed by FORTV. During the project, it was ascertained that there is inadequate knowledge pertaining to crack repair.

    The goals of this project were the following:Suggest a method or a tool to evaluate the extent of cracking in concrete structures which are included in protective facilitiesDescribe which parameters can initiate cracking.Describe repair methods to reinstate the functionality of concrete structures.

    Cracking naturally takes place during the normal use of a concrete structure without influencingthe structure’s functionality given that it is designed correctly. However, there are other mechanisms which can initialize cracking in concrete structures. These mechanisms take place during various time periods (hardening, after hardening andduring the service life). Three crack groups have been identified accordingly: a) cracks due to poor workmanship, b) cracks due to chemical deterioration mechanisms and c) loading cracks.

    Damage identification and a condition assessment can be conducted in different stages to determine the extent of cracking. It is firstly recommended to review the existing documentation coupled to the structure, followed by a preliminary inspection (visual), additional non-destructive testing and lastly destructive testing. Repairs are selected according to the source of the damage, it is to say concrete defects or corroded reinforcement. In addition, the functionality requirements for the structure shall be evaluated and the selected methods shall be assessed according to e.g. lifespan and cost.

     

  • 242.
    Williams Portal, Natalie
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Flansbjer, Mathias
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Assessment of Fire Exposed Concrete with Full-field Strain Determination and Predictive Modelling2019Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A condition assessment of civil engineering structures is typically performed after the occurrence of a fire incident to determine the remedial actions required out of a structural point of view. A condition assessment is based on the mapping of damage on the given structure, which is traditionally executed via methods that yield indirect results related to surface and/or geometric properties. To be able to predict the accurate fire resistance performance of a given structure, it is most suitable to apply a mapping method which can be directly coupled to the change in material properties of concrete at high temperatures. The aim of this study is to explore the potential of applying an innovative damage mapping methodology directly coupled to the change in material properties of concrete at high temperatures. This methodology consists of optical full-field strain measurements based on Digital Image Correlation (DIC) coupled with a predictive model based on finite-element analysis (FEA). An experimental study was firstly conducted to expose concrete slabs to a standard fire curve. Subsequently, compression tests were performed on drilled cores taken from the damaged induced specimens, all while optically measuring the full-field strain on a specimen surface. As a preliminary step, an FE model of a fire exposed core was developed based on input data from standard temperature-dependent properties. The analysis consisted of a sequentially coupled thermal stress analysis to solve the multiphysics problem. The model was able to capture the temperature distribution in the concrete with enough certainty given the choice of input data. The resulting strain along the height of the core was also comparable to the experimental optical strain measurements, particularly as the distance increased from the fire exposed surface. These results can be practical when assessing the required strengthening actions to restore the load carrying capacity and durability of the concrete structure.

  • 243.
    Williams Portal, Natalie
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Flansbjer, Mathias
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Honfi, Daniel
    RISE - Research Institutes of Sweden, Samhällsbyggnad, Byggteknik.
    Testing of self-supporting laminated glass balustrades2019Rapport (Annet vitenskapelig)
    Abstract [en]

    The work carried out within Task 2 Experimental work of the ÅForsk funded project "Structural safety of glass components" is presented in this report. The main goal of this project was to improve the understanding about the structural safety of self-supporting glass components. In particular, the results of the project intended to extend the current knowledge about the effect of impact and related testing methods regarding the safety of glass structures.

    Static and impact tests were conducted on a self-supporting glass balustrade with point-fixings. The laminated glass consisted of two 10 mm thick layers of laminated glass and a 0.76 mm thick interlayer made of EVA (ethylene vinyl acetate). A static line load was cyclically applied to the top of the specimen to gain an understanding of the static behaviour of the glass structure and to minimize the settlement in the structure prior to applying impact loading. The specimen was subsequently subjected to dynamic loading by impact tests based on EN 12600 (pendulum impact) with different drop heights until attaining failure. The dynamic structural response of the glass balustrade was analysed by three-dimensional Digital Image Correlation (3D-DIC). This measurement technique made it possible to directly relate the measurement of any point to the specimen and to study the deformed 3D shape in detail during the impact test. The FE-analysis (FEA) conducted using SJ Mepla was found to correlate rather well with the dynamic test results particularly up to the initial peak displacement.

  • 244.
    Williams Portal, Natalie
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Flansbjer, Mathias
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Malaga, Katarina
    RISE - Research Institutes of Sweden, Samhällsbyggnad, CBI Betonginstitutet.
    Mueller, Urs
    RISE - Research Institutes of Sweden, Samhällsbyggnad, CBI Betonginstitutet.
    Anchorage of Textile Reinforcement in High-Performance Concrete2017Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The mechanical properties of textile reinforced high-performance concrete (TRHPC) applied in innovative lightweight sandwich elements has been investigated in the framework of EC supported FP7 project, H-House (Healthier Life with Eco-innovative Components for Housing Constructions). TRHPC offers new possibilities for architects and engineers to create thinner and more durable concrete façade elements. Textile reinforcement grids are typically woven from non-metallic rovings usually consisting of continuous glass, rock or carbon fibres. The most promising performing textile reinforcement alternative in terms of mechanical and durability performance consists of carbon fibres. Carbon fibres do however have an inherent smooth surface which is unfavourable concerning its bond to the cement paste, which is often improved by polymer-based coatings. The bond behaviour, being a critical design parameter, should be investigated for TRHPC in order to understand limitations regarding required anchorage lengths for use in applications such as façade elements. The aim of this study was to quantify and verify the required anchorage length for a selected epoxy impregnated carbon textile reinforced TRHPC combination. To achieve this aim, the bond behaviour, leading to a suitable anchorage length (or overlap), was firstly studied by means of pull-out tests. Thereafter, the ultimate strength of the composite material was measured via uniaxial tensile testing with and without an overlap splice according to the findings from the pull-out tests. Optical measurements during the pull-out tests were performed using a video extensometer technique and by Digital Image Correlation (DIC) for the uniaxial tensile tests. Results indicated that the required anchorage length to yield rupture of the textile reinforcement in pull-out was deemed appropriate as an overlapping length when tested in tension. The combination of these two experimental methods on the composite level was useful for determining the overlapping length required for the TRHPC which could be applied in larger scale applications.

  • 245.
    Williams Portal, Natalie
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Flansbjer, MathiasRISE - Research Institutes of Sweden, Säkerhet och transport, Safety.Mueller, UrsRISE - Research Institutes of Sweden, Samhällsbyggnad, CBI Betonginstitutet.
    Analysis of the Flexural Behavior of Textile Reinforced Reactive Powder Concrete Sandwich Elements Using Optical Measurements2018Konferanseproceedings (Fagfellevurdert)
    Abstract [en]

    Prefabricated and non-load bearing sandwich façade elements were developed using Textile Reinforced Reactive Powder Concrete (TRRPC) along with low density Foamed Concrete (FC) and Glass Fiber Reinforced Polymer (GFRP) continuous connecting devices. Four-point bending tests were performed on large-scale TRRPC sandwich element beams to characterize the structural performance, which included the flexural capacity, level of composite action, resulting deformation, crack propagation and failure mechanisms. Optical measurements based on Digital Image Correlation (DIC) were taken simultaneously to enable a detailed analysis of the underlying composite action. The structural behavior of the developed elements was found to be highly dependent on the stiffness and strength of the connectors to ensure composite action between the two TRRPC panels.

  • 246.
    Williams Portal, Natalie
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Flansbjer, Mathias
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Mueller, Urs
    RISE - Research Institutes of Sweden, Samhällsbyggnad, CBI Betonginstitutet.
    Experimental Study on Anchorage in Textile Reinforced Reactive Powder Concrete2017Inngår i: Nordic Concrete Research, ISSN 0800-6377, Vol. 57, nr 2, s. 73-88, artikkel-id 6Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The EC funded project SESBE (Smart Elements for Sustainable Building Envelopes) focused on utilizing new types of cementitious materials for reducing the mass and thickness of façade elements while increasing their thermal performance. A method enabling the quantification and verification of the required anchorage length for a given textile reinforced reactive powder concrete (TRRPC) is presented. At the material level, tensile tests were conducted to determine the tensile properties of the reinforcement. Pull-out tests were applied to quantify the required anchorage length, while uniaxial tensile tests were performed to quantify the ultimate strength and verify the suitability of the anchorage length at the composite level. The combination of these methods was deemed useful to determine the overlapping length required for larger scale façade applications.

  • 247.
    Williams Portal, Natalie
    et al.
    RISE - Research Institutes of Sweden, Samhällsbyggnad, CBI Betonginstitutet.
    Flansbjer, Mathias
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Zandi, Kamyab
    RISE - Research Institutes of Sweden, Samhällsbyggnad, CBI Betonginstitutet.
    Wlasak, Lech
    Mostostal Warszawa SA, Poland.
    Malaga, Katarina
    RISE - Research Institutes of Sweden, Samhällsbyggnad, CBI Betonginstitutet.
    Bending behaviour of novel Textile Reinforced Concrete-foamed concrete (TRC-FC) sandwich elements2017Inngår i: Composite structures, ISSN 0263-8223, E-ISSN 1879-1085, Vol. 177, s. 104-118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel sandwich element design consisting of two facings made of carbon reinforced Textile Reinforced Concrete (TRC), a low density foamed concrete (FC) core and glass fibre reinforced polymer (GFRP) connecting devices was experimentally investigated according to quasi-static and cyclic quasi-static fourpoint bending. Optical measurements based on Digital Image Correlation (DIC) were taken during testing to enable a detailed analysis of the bending behaviour and level of composite action. A model, verified by the experiments, was developed based on non-linear finite element analysis (NLFEA) to gain further insight on the failure mechanisms. Under both loading conditions, the bending behaviour of the TRCFC composite elements was characterized by favourable load bearing capacity, partial composite action, superior ductility and multiple fine cracking. The connecting devices were found to be the critical elements causing the initial failure mechanism in the form of localized pull-out within an element.

  • 248.
    Willstrand, Ola
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Att hantera brandrisker med Li-jonbatterier i fordon2019Rapport (Annet vitenskapelig)
    Abstract [sv]

    Efterfrågan på elfordon fortsätter öka över hela världen. Då elfordonen blir vanligare kommer även olyckor med dessa fordon öka. En krock eller brandincident riskerar skada litiumjonbatteriet, vilket innebär nya risker för passagerare, räddningstjänst och andra som är involverade i efterhanteringen. I projektet har riktlinjer och rekommendationer tagits fram för hantering av krockskadade elfordon samt brandsäkerhet vid laddning. Dessa rekommendationer är lättlästa och riktar sig mot alla inblandade aktörer.

    Det övergripande syftet med projektet var att studera alla tänkbara brandrisker kopplat till litiumjonbatterier i fordon, samt hur riskerna och konsekvenserna av en termisk incident kan minskas. Som en del av potentiella säkerhetssystem har fast monterade släcksystem utvärderats genom brandförsök. Då släcksystem är vanligt förekommande för att skydda motorrum på tunga fordon, i synnerhet bussar, är det viktigt att undersöka vilka möjligheter dessa system har att användas som brandskydd för litiumjonbatterier. Resultaten visar att det finns potential att påverka spridning av termisk rusning inuti batteriet om släckmedlet appliceras inuti batteripacket, även med mycket begränsad mängd vätska.

    Information från projektet ger industrin och andra aktörer möjlighet att på ett konstruktivt sätt höja säkerheten genom att adressera de risker som finns, samtidigt som omställningen till fossilfria bränslen kan fortgå med fortsatt förtroende från allmänheten.

  • 249.
    Willstrand, Ola
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Fire risk management for vehicles2017Inngår i: Gulf Fire, ISSN 2059-691X, nr 7, s. 66-68Artikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 250.
    Willstrand, Ola
    et al.
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Karlsson, Peter
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    Brandt, Jonas
    RISE - Research Institutes of Sweden, Säkerhet och transport, Safety.
    New certification rules for fire detection in vehicles2017Inngår i: 16th International Conference on Automatic Fire Detection & Suppression, Detection and Signaling Research and Applications Conference: Proceedings, 2017, Vol. 2, s. 105-112Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Detection of fires in vehicle engine compartments is challenging. High airflows, large temperature variations, dirty environment and complicated geometries make it difficult to determine the optimal type of detection technology and adequate location of sensors. A new test method has been developed for evaluation of fire detection systems meant for engine compartments of heavy vehicles. The test method considers all typical challenges normally encountered in an engine compartment, evaluating both detection system performance and durability. Certification rules connected to the new test method will ensure high quality and high performance of certified fire detection systems, increasing fire safety of vehicles.

    This paper gives an outline of the new certification rules, test method and corresponding research.

23456 201 - 250 of 268
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
v. 2.35.9