Papers by Keyword: Fire

Abstract: The construction, operating principles, and Li-ion battery thermal runaway mechanisms were analyzed. The external mechanical damage to a Li-ion battery with the uncontrolled thermal runaway development was investigated. The battery self-heating temperature regime was determined. A possible reactions set leading to intense materials self-heating and decomposition was considered. The battery self-heating stopping by immersing it in a container with a water excess relative to the stoichiometric amount for the lithium metal maximum mass that can accumulate was investigated. The change in resulting aqueous solution pH was measured, and the hydrogen release was also recorded. Reaction completion time dependences was established. The water required amount to absorb the heat that could be released during the reaction was calculated, which correlated with the experimental data. Possible measures to Li-ion batteries prevent and stop the burning were considered.

Abstract: The aim of the work was to determine the possibility of not taking into account the orientation (vertical or horizontal) of the studied elements of steel-reinforced concrete slabs with a corrugated profile during their heating in a modular small-sized fire furnace. The work investigated the temperature distributions on the outer surface of the corrugated ceiling profile of a steel-reinforced concrete slab of horizontal orientation simulated in the fire furnace chamber. To create geometric models of the fire furnace chamber and the studied element, a CAD software complex was used. To solve the heat engineering problem, mathematical (numerical) methods were used, based on solving systems of differential equations of continuous media such as the Navier-Stokes equation and the Fourier heat conductivity equation. According to the results obtained, the temperature distribution on the outer surface of the steel profile of the reinforced concrete slab is uniform, the temperature deviation in different places on the surface does not exceed 7 %. The maximum temperature on the heating surface of the steel profile of the reinforced concrete slab in the last minute of computer simulation reached 921 °С and the average temperature at this time over the entire surface of the structure was 917 °С. To determine the appropriate orientation of the test sample during fire tests, a comparison of the obtained temperature distributions on the outer surface of the corrugated profile of a horizontally placed reinforced concrete slab with the temperature distributions on the outer surface of the corrugated profile of a vertically placed reinforced concrete slab, which were given in the previous work was made. Analysis of the average surface temperatures of the corrugated profile of a reinforced concrete slab of horizontal and vertical orientation showed that the temperature distribution over the surface of the profile was uniform in both cases and the results obtained show good reproducibility of the experiment during computer simulation. And the orientation of the tested elements does not affect the temperature distribution over the outer surface of the corrugated profile of a reinforced concrete slab in the simulated furnace.

Abstract: Fire produces unique effects on steel structures which can compromise the residual capacity and therefore the structural response if they impact jointly with other natural hazards, such as earthquakes. This work presents a procedure that allows for the extension of the analysis method introduced in the 1990s by Fajfar and Gaspersic and outlined in EC8 (referred to as the N2 method) for the case of Multi-Hazard (MH) analysis, specifically for hazard-chain scenarios involving earthquake and fire. The goal is to assess the structural performance at the end of the sequence of considered events. By appropriately modeling the structure considering elasto-plastic behaviour, it becomes possible to observe the structural response as the plasticization of structural elements progresses: in this context, accounting for material and geometric nonlinearities has proven essential, since the material and structure's behaviour under fire are governed by complex phenomena, due to the significant deformations and distortions involved. The hazard-chain scenario here discussed is characterised by the consecutiveness of main earthquake event and fire; the proposed procedure is then applied to a 2D steel structure. Results highlight that neglecting possible hazard interactions could lead to an erroneous evaluation of the residual structural capacity.

Abstract: Reinforced concrete (RC) bearing walls are commonly used in building structures to resist axial and lateral loads. Therefore, their ability to withstand loads when exposed to fire is important. The behavior of RC walls under fire exposure is affected by various factors, such as slenderness ratio, concrete strength and composition, and axial load. This paper investigates the effect of slenderness ratio on the structural performance of RC walls subjected to fire. A series of numerical simulations were conducted on RC walls with different slenderness ratios. The simulations are performed on a three-dimensional (3D) finite element (FE) model, after validating its thermal and structural behavior using previously published experimental data. The walls were exposed to standard fire curves (ISO834) on one side. The thermal and structural response of the walls were assessed in terms of axial deformations, out-of-plane deformations, and fire resistance. The results showed that slenderness ratio had a significant influence on the fire behavior of RC walls. The walls with higher slenderness ratios exhibited higher temperature gradients and larger deflections compared to the walls with lower slenderness ratios. Moreover, the fire resistance of the walls was significantly reduced when the slenderness ratio was increased.

Abstract: In recent years, in connection with numerous incidents of fires occurring in hotels, many studies have been conducted on risk management issues, as well as actions in emergencies. Research has often been limited to incident analysis rather than addressing how to manage fire safety to minimize risks and did not sufficiently take into account the features of the construction of the hotel building and the characteristics of materials. The existing state of management and regulation of material damage risks from fires and emergencies does not fully take into account the approaches and means for their minimization, in particular in hotels. There is an increasing need for the use of assessment methods that will help in the performance of risk management functions. There is a need to find effective mechanisms for assessing the risks of material damage of building construction and materials of high-rise rooms from fires and emergencies. Fires in public sites on the example of hotels have been taken for research. There is an increasing need for the use of assessment methods that will help in the performance of material loss risk management functions. During the period of martial law, the method of assessing material damage to the building presented in the article can be used to assess material damage from destruction and fires for future compensation. With the help of this method, it is possible to estimate probable material damage from fires and emergencies, which will allow them to be used in supervisory and preventive activities and the insurance industry. Thus, fires in hotels cause significant material damage, and recently, as statistics show, also human losses. In hotels, it is important to ensure the protection of the building, premises and people from fire. Therefore, the issue of assessing fire risks is currently relevant. Fire risk assessment is an important part of fire science and safety engineering.

Abstract: Consideration was given to the issues relating to safety conditions and security arrangements during the thermal decomposition of wood at the time of the fire in the premises of domestic buildings. The data of experimental investigations obtained for the thermal decomposition of wood were given with the measurement data of the concentration of toxic gases (СО, СО₂), oxygen (О₂), and temperature depending on time and fire spreading conditions in the premises. The studies were carried out by comparing the changes in the temperature of the solid flammable materials with time and the emission intensity of toxic gas (СО, СО₂) under the limited oxygen access at the time of the fire. The research data confirm those obtained for the gaseous atmosphere composition in the premises during the thermal decomposition of the solid flammable materials.

Abstract: In view of the climate emergency and the need for energy transition, the use of materials with low environmental impact based on plant co-products or from recycling is strongly encouraged. Biobased materials have been developed in recent years and have shown interesting performances, particularly for the thermal insulation of buildings. Nevertheless, their use is still hampered by the lack of rules for their use and control of their behaviour in normal or accidental conditions of use such as excess water or fire. In this work, the behaviour of biocomposites based on cereal straw exposed to high temperatures was studied. The objective is to evaluate the effect of this temperature increase on the mechanical strength of the material and its thermal properties using different heating scenarios. The biocomposites considered for this study were developed as part of the PEPITE project funded by the “Region Centre Val de Loire”. They are materials composed of two different binders: lime, and plaster, straw aggregates and additives (air entraining agent, casein protein and biopolymer). In order to simulate fire, two temperatures were chosen for the study 200°C and 210°C, using four different heating rates to study their impact on the behaviour of dry and wet conditions of biocomposites. The purpose of this tests is to examine whether the material retains its insulating properties and its buildability. The results showed that the use of additives had negative effects on the behaviour of the materials with respect to temperature increase. Their use accelerates the degradation and burning of biocomposites faster than for samples without additives. Plaster based composites show a better behavior to high temperature than lime-based composites. Nevertheless, lime composites have a higher strength than plasters. Furthermore, the thermal conductivity of plaster is lower than that of lime. It should be noted that the heating rate has a significant impact on the behaviour of the material, the slower the rate, the more the material is degraded.

Abstract: The analysis and necessity for studying of burning processes of systems formed by coal dust and methane for the purpose of development the effective activities on the enterprises of coal branch were shown. The results demonstrate the role of nonflammable components in the combustion processes of air suspension in heterogeneous systems. Also the dependence of the critical conditions creation for flame propagation in air suspension of sucrose from the average particle diameter at different temperatures of the ignition source is presented. The necessity of taking into account the experimental and methodological experience of other industries for the study of air suspension sensitivity to the initiating influence of the ignition source is explored. The requirements to the installation and methodology for studying the sensitivity of coal dust air suspension as one of the main factors preventing explosions of heterogeneous systems in the coal industry are formulated.

Abstract: This paper presents possible deviations between advanced (performance-based or ‘realistic’) and simplified calculations of initiation and spread of a fire in a factory for the production of insulation panels made of extruded polystyrene (XPS). Simplified procedures, discussed in the paper, are founded on several assumptions regarding the evolution of the fire. They are normally based on a great deal of practical experience of the fire designer and/or reports of eyewitnesses of similar fires. Provided that the latter are easily accessible, such procedures are fast and can provide a reasonably good first impression regarding the expected fire as the paper shows. However, they also almost inevitably lead to temperatures which are somewhat underestimated in the most intense fire phase but are overestimated in the decaying phase. Hence, for a more reliable calculation, advanced procedures are recommended.

Abstract: This paper presents the possible deviations between “realistic” (performance-based) calculations of fire resistance of steel structures and corresponding calculations made by one of the often used simplified (prescriptive) procedures of EN 1993-1-2 i.e. the method of critical temperature (MCT). The comparison is done for a case of an assembly consisting of a steel beam and a steel girder connected to each other by a bolted fin-plate connection. For such structure the MCT method suggests that the structural fire resistance is 50 minutes. However, the realistic fire resistance calculated by an advanced performance-based procedure is evaluated to 44 minutes. Although the discrepancy between the results of both methods is not significant in the presented case, this finding implies that MCT can be on the unsafe side for some cases. More future debates and clarifications are therefore encouraged regarding the actual limits of the applicability of the simplified procedures.