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  • 1.
    Fjærestad, Janne Siren
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Meraner, Christoph
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Jiang, Lei
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Stølen, Reidar
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Brannsikkerhet ved oppføring og rehabilitering av bygg2023Report (Other academic)
    Abstract [en]

    Fire safety during construction and rehabilitation of buildings. This study deals with how the covering of buildings during the construction or rehabilitation of buildings affects fire safety and to what extent the regulations take this into account. The main focus has been mapping relevant requirements, recommendations, and performances related to the covering of buildings, mapping available materials, investigating the material’s fire properties, and modelling the spread of smoke within the covering. A mapping of the relevant laws and regulations applied for constructing and rehabilitating buildings has been carried out. The mapping has shown that demands are placed on owners, users, project owners, builders, businesses, employers, planners and contractors through many different laws and regulations. The people involved can have several roles, and similar roles have different names in the various regulations. For buildings in use, fire safety must be ensured for both the users and workers. It also applies that both the owner and the users are responsible for ensuring fire safety. It requires good communication and cooperation between different actors to ensure that fire safety is maintained for all involved, during the construction and rehabilitation of buildings. When covered scaffolding is used, the Regulations concerning the performance of work, use of work equipment and related technical requirements [10] require that the covering satisfy the fire requirements for materials used in escape routes (§17-20). The guideline to the Norwegian Regulations on technical requirements for construction works, TEK10, (Veiledningen til TEK10) §11-9, provides pre-accepted performance levels. For escape routes, class B-s1,d0 (In 1) is specified for walls and ceilings. There is no requirement for fire classification of the walkways in the scaffolding under the applicable laws and regulations. We believe there should be requirements for fire classification of the walkways, in the same way as for the covering, i.e., B-s1,d0 (In 1) for surfaces on walls and ceilings and Dfl-s1 (G) for surfaces on floors. The simulations of the spread of smoke from a fire inside a building during construction or rehabilitation show that the spread of smoke is affected when the scaffolding around the building is covered. Covering around the sides leads to a greater horizontal spread of smoke in the scaffolding than without covering. When the cover also has a roof, the smoke first accumulates underneath the cover's roof before it eventually also fills up with smoke down the floors of the scaffolding. The simulations showed that establishing an open field in the upper part of the cover would ventilate the smoke gases effectively, and the spread of smoke was essentially the same as for a cover without a roof. In addition, the simulation indicated that the air flow through the walkways in the scaffold could be an important factor in reducing the covering's negative effect on the spread of smoke. Of the 64 different products used for covering found in the survey, 35% had full classification according to EN 13501-1 (such as B,s1-d0). About 6% stated that the product was not flame retardant. Of the remainder, it was evenly distributed between those who stated a fire classification according to other test methods, those who did not provide any information on the fire properties and those who stated that the product was flame retardant without further specification. The mapping also indicates that the products from market leaders used by large general contractors provide products with documented fire properties. Conversations with two of Norway’s largest fire and rescue services shed light on several challenges connected to covering scaffolding and construction during firefighting activities. They pointed out that the covering could cause challenges and delays throughout their efforts. The covering gives a reduced visual overview of the spread of smoke and the location of doors and windows. This information is important for planning both extinguishing and smoke diver efforts. In addition, the covering can be an obstacle to the actual extinguishing effort, the use of an extinguishing agent and smoke divers and rescue efforts.

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  • 2.
    Ingason, Haukur
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Li, Ying Zhen
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Arvidson, Magnus
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Jiang, Lei
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Fire tests with automatic sprinklers in an intermediate scale tunnel2022In: Fire safety journal, ISSN 0379-7112, E-ISSN 1873-7226, Vol. 129, article id 103567Article in journal (Refereed)
    Abstract [en]

    A series of 1:3 intermediate scale tunnel fire tests was performed to investigate the performance of a fully automatic sprinkler system in a road tunnel. The experiments were carried in a container tunnel with scaled geometry, using wood pallets as the fire source to simulate HGV fires. The activation of the sprinklers was simulated by using thermocouples that corresponded to a given Thermal Response Index (RTI) of a sprinkler bulb or a link. A total of 12 tests were carried out with varying longitudinal velocities (0.8–1.7 m/s), sprinkler activation temperatures (68–141 °C), water densities (2.9–8.7 mm/min) and types of arrangement of the fuel. The activation times, number of activated sprinklers, maximum heat release rates and other key parameters are presented and analyzed. The results show that the water density plays a key role in the performance of the automatic sprinkler systems tested. A high tunnel ventilation velocity, low water density and low sprinkler activation temperature are not recommended. © 2022 The Authors

  • 3.
    Jiang, Lei
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Safety and Transport, Safety.
    Use of mobile fans during tunnel fires2020In: Tunnelling and Underground Space Technology, ISSN 0886-7798, E-ISSN 1878-4364, Vol. 106, article id 103618Article in journal (Refereed)
    Abstract [en]

    Smoke control is a key issue in tunnel fire accidents. While jet fans have been widely used in road tunnels, mobile fans provide a good complement, due to its flexibility to operate, especially if there are no fixed jet fans present. To confirm the feasibility of a mobile fan system, full scale fire tests were conducted in Kalldal tunnel in Sweden, with fire size in the range of 1–2.6 MW and a mobile fan placed at the tunnel portal. In the tests, it takes about 4–5 min to establish full flow in the opposite direction and the final flow velocity can reach 1.5–1.9 m/s. To describe the transient behavior of flow development inside tunnel, a one-dimensional lumped theoretical model has been developed. The model takes into account the pressure losses of external wind, the stack effect of fire and friction losses over tunnel walls and two portals. The model is validated using the data from Kalldal tunnel fire tests. Results show that the model can well predict the initial and final steady state velocity, but underestimates the flow development. The model gives prediction on the safe side.

  • 4.
    Jiang, Lei
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety. Ningbo University, China.
    Olofsson, Anna
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Evegren, Franz
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Mindykowski, Pierrick
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Effect of opening geometries on fire development in a ro-ro space2023In: Ships and Offshore Structures, ISSN 1744-5302, E-ISSN 1754-212X, p. 272-284Article in journal (Refereed)
    Abstract [en]

    A series of model scale experiments were conducted to study the fire development in a ro-ro deck with various opening geometries. The experiments were performed in a 1/8 reduced scale model with a heptane pool fire as fire source. Experimental results show that both the ventilation factor and the opening position affect the fire development. The critical opening ratio for the fire to self-extinguish is 4%, with the opening locating at the bottom of the side walls while no self-extinction is found for other tests. A higher opening position and a larger opening height provide better flow exchange between the deck and the ambient, but this effect is only obvious for 4% opening. Numerical study shows that Fire Dynamic Simulator used with default simple settings underestimates the fire development and yields an early extinction when fire self-extinction occurs. For freely developed fire with large openings, FDS gives more close results to experiments.

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  • 5.
    Li, Ying Zhen
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Safety.
    Ingason, Haukur
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Safety.
    Jiang, Lei
    RISE - Research Institutes of Sweden (2017-2019), Safety and Transport, Safety.
    Influence of tunnel slope on smoke control2018Report (Other academic)
    Abstract [en]

    The critical velocity and backlayering length in sloped tunnels are investigated by numerical simulations using FDS. Simulation in two full-scale tunnels, with negative slopes ranging up to -18 % and heat release rates from 5 to 100 MW were carried out.

    The results show that NFPA 502 equation significantly overestimates the effect of negative slopes.

    The equation proposed by Atkinson and Wu is found to be in closer agreement with the results. A simplified correlation, i.e. Eq. (12), is proposed and recommended for practical use.

    The previous correlation for dimensionless backlayering length, Eq. (3), is valid for tunnels of various slopes and aspect ratios, and can be used for prediction of backlayering length.

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  • 6.
    Olofsson, Anna
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Safety.
    Evegren, Franz
    RISE Research Institutes of Sweden, Safety and Transport, Safety.
    Mindykowski, Pierrick
    RISE Research Institutes of Sweden, Safety and Transport, Safety.
    Jiang, Lei
    RISE Research Institutes of Sweden, Safety and Transport, Safety.
    Ukaj, Kujtim
    RISE Research Institutes of Sweden, Safety and Transport, Safety.
    Zawadowska, Aleksandra
    RISE Research Institutes of Sweden.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Safety and Transport, Safety.
    RO5 ro-ro space fire ventilation: Summary report2020Report (Other academic)
    Abstract [en]

    This report is the final report from the research project RO5. The report summarises the results from the research project RO5. The report consists of summary from a literature study, from computer simulations and from model scale tests. This, together with results from full scale demonstrational test (documented only in this report) leads to the conceptional solutions and recommendations presented in this report. The project focused aim was to investigate the effects of ventilation on fire development in ro-ro spaces with different ventilation conditions.

    Important conclusion from the literature study is that ventilation is primary to prevent flammable and other harmful gases from accumulating in the spaces, and the mechanical ventilation is not designed to be functional in case of fire. It is a must for the crew to gain knowledge about the ventilation system (i.e. fans, inlets and outlets) and its capacity from tests and experiences. It is important that guidelines, rules and routines are established for using the ventilation system in typical conditions (loading/unloading etc.) and that it is documented and passed on to provide guidance for the ship's crew.

    One of the most important conclusions from the model scale tests and numerical simulation study is that distinct limitation is found for 4% opening of space sides (natural ventilation) for the fire self-extinction to occur. This is dependent on the height and shape of the opening. For the mechanical ventilation case, in case of fire, stopping the ventilation is the best way to reduce the fire intensity. The tests show that mechanical ventilation is vital for the fire to continue to burn. The recommendations aim at giving advise concerning ventilation in case of fire and how to deal with the ventilation at different ro-ro spaces.

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  • 7.
    Olofsson, Anna
    et al.
    RISE Research Institutes of Sweden, Safety and Transport.
    Mindykowski, Pierrick
    RISE Research Institutes of Sweden, Safety and Transport.
    Jiang, Lei
    RISE Research Institutes of Sweden, Safety and Transport.
    Rakovic, Alen
    RISE Research Institutes of Sweden, Safety and Transport.
    Ingason, Haukur
    RISE Research Institutes of Sweden, Safety and Transport.
    Model scale tests of a ro-ro space fire ventilation2019Report (Other academic)
    Abstract [en]

    The report contains results from a parametric study using model scale tests with natural and mechanical ventilation on ro-ro ship. Two types of fuels were used, heptane liquid fire and wood cribs. The heptane fire was used for the test series using natural ventilation and wood cribs were used in the test series using mechanical ventilation. The tests were carried out in a scale model 1:8 made of steel covered with 6 mm thick gypsum boards. The size of the model was 14.4 m long, 2.8 m wide and 0.6 m high. For natural ventilation different opening sizes (0, 1, 4 and 10% of the area of the walls along the sides) and shapes were located at different hull sides and sill heights. For mechanical ventilation both inlets supply, and outlets extracts were attached to the model and external fans combined with opening or closing of one end side. The air change per hours (ACPH) were set at 0, 10 and 20.

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  • 8.
    Skilbred, Ellen Synnøve
    et al.
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Sæter Bøe, Andreas
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Holmvaag, Ole Anders
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Jiang, Lei
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Fjærestad, Janne Siren
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Brannsikkerhet i semiautomatiske parkeringsanlegg2023Report (Other academic)
    Abstract [en]

    Fire safety in semi-automatic parking facilities

    The main goal of this study is to contribute to increased safety in semi-automatic parking facilities. Semi-automatic parking facilities are parking facilities with a system for automatic stacking of cars, but in contrast to fully automatic parking facilities, these are not closed, compact, and unavailable for the public. The study is financed by The Norwegian Directorate for Civil Protection (DSB) and Norwegian Building Authority (DiBK). A fire simulation was conducted to compare fire spread in a semi-automatic parking facility to fire spread in an ordinary parking facility. The results indicate that the spread of fire from the car that was first ignited to another car happens approximately equally fast in the two scenarios. Thereafter, the fire spread faster in the semi-automatic parking facility compared to the ordinary parking facility. Although these results should only be considered as indicative, they do show that decreasing the distance between rows of cars can lead to a much faster fire spread. The simulation also shows that the size of a fire in a relatively closed-off parking facility is not necessarily controlled by the number of cars but by the access to air. Hence, the number of openings and properties of ventilation systems in such facilities are important factors to consider when assessing fire safety. A study of regulations and experiences with semi-automatic parking facilities in Norway and other countries as well as aspects that increase risks in semi-automatic parking facilities was conducted. No specific fire-related experiences were discovered, but this is not surprising when considering that fires in parking facilities are relatively rare and there are relatively few semiautomatic parking facilities. In addition, these types of facilities are relatively new. The study found regulations for fully automatic parking facilities in Norway, but semiautomatic parking facilities are not covered by the same regulations. The current regulations do not ensure that the authorities are informed when automatic car-stacking systems are installed in existing parking facilities that are open to the public. There are no regulations ensuring that a fire safety assessment is conducted when an automatic car-stacking system is installed in an existing building regulated for parking that is accessible to the public. It is our opinion that there is a need for a new assessment of fire safety when a system for car stacking is established in an existing parking facility.

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  • 9.
    Yao, Y.
    et al.
    China University of Mining and Technology, China.
    Wang, J.
    China University of Mining and Technology, China.
    Jiang, Lei
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Wu, B.
    China University of Mining and Technology, China.
    Qu, B.
    China University of Mining and Technology, China.
    Numerical study on fire behavior and temperature distribution in a blind roadway with different sealing situations2023In: Environmental Science and Pollution Research, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 30, p. 36967-36978Article in journal (Refereed)
    Abstract [en]

    Blind roadways have only one portal which connects with other types of mine roadways. Sealing the fire area in a blind roadway is an effective method of disaster relief in a mine. To understand the effect of sealing ratio and sealing distance on fire behavior, Fire Dynamics Simulator (FDS 6.6) was used to study blind roadway fires with different fire scenarios. Results indicate that the smoke flow velocity increases significantly with the increase of sealing distance. The fire in the blind roadway is ventilation-controlled. When the sealing ratio reaches 80%, the fire self-extinguishes completely. Otherwise, the fire experiences an extinguishing-reburning cycle periodically. Besides, an empirical model is proposed to predict the downstream temperature distribution beneath the ceiling in the region from fire source to sealing position. The predictions by the proposed model comply well with the simulation and experimental results from our and others’ studies. This study provides new insights into the sealing strategies in blind roadway fires, and the outcomes of the current study are of guiding significance for the fire rescue in the blind roadways or similar structures. © 2022, The Author(s)

  • 10.
    Zhang, Yue
    et al.
    China University of Mining and Technology, China.
    Yao, Yongzheng
    China University of Mining and Technology, China.
    Ren, Fei
    China Academy of Safety Science and Technology, China.
    Zhu, Hongqing
    China University of Mining and Technology, China.
    Zhang, Shaogang
    Shanghai Maritime University, China.
    Jiang, Lei
    RISE Research Institutes of Sweden, Safety and Transport, Fire and Safety.
    Effects of ambient pressure on smoke propagation in inclined tunnel fires under natural ventilation2023In: Environmental Science and Pollution Research, ISSN 0944-1344, E-ISSN 1614-7499, Vol. 30, p. 65074-65085Article in journal (Refereed)
    Abstract [en]

    This paper systematically studied the coupling effect of ambient pressure and tunnel slope on temperature distribution and smoke propagation in full-scale tunnel fires under natural ventilation by FDS. The downstream length (longitudinal length from fire source center to tunnel downstream exit) was also considered. The concept of “height difference of stack effect” was put forward when analyzing the mutual effect of tunnel slope and downstream length on smoke movement. The results show that the maximum smoke temperature beneath the ceiling decreases with the increasing ambient pressure or tunnel slope. The longitudinal smoke temperature decays faster with the decreasing ambient pressure or slope in inclined tunnel. The induced inlet airflow velocity increases with the increasing height difference of stack effect, while decreases with the increasing ambient pressure. And the smoke backlayering length decreases with the increasing height difference of stack effect. Taking heat release rate (HRR), ambient pressure, tunnel slope and downstream length into account, the prediction models of dimensionless induced inlet airflow velocity and smoke backlayering length in inclined tunnel fires at high altitude were developed, which agree well with our and others’ results. The outcomes of current study are great meaningful to fire detection and smoke control in inclined tunnel fires at high altitude. © 2023, The Author(s)

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