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The flame spread behavior over a filter paper in opposed flow was investigated on the ISS/Kibo, and the results were compared with the flammability map predicted in advance by scale analysis for a two-dimensional flame. The on-orbit experiments were conducted in the solid combustion experimental module (SCEM) as the first combustion test of the FLARE project by JAXA. A filter paper with a length of 130 mm, a width of 40 mm or 20 mm, and a thickness of 0.12 mm was used as the specimen. The opposed flow velocity and the oxygen concentration were varied from 0 cm/s to 25 cm/s, and from 13.5% to 34%, respectively. The ambient pressure is 101.3 kPa. The predicted limiting curve reasonably agreed with the minimum limiting oxygen concentration observed. On the other hand, in extremely slow flows, very robust flames were observed beyond the limiting curve. When the condition reached the limit of two-dimensional flame, the flame front changed from a linear shape to a spherical shape (flamelet) to shorten the preheat zone length, reducing the radiative heat loss to survive. In these cases, the flamelet was sustained for a long time (> 100 s), and a large amount of decomposed gas was released at the periphery of the pyrolysis zone generating a combustible vapor cloud around the spherical flame font. The presence of a long-life robust flamelet and the accumulation of such combustible mist can be fire hazards in microgravity. [ABSTRACT FROM AUTHOR]

This paper studies the pyrolysis mechanisms of Nomex insulation paper in nitrogen and air atmospheres. The Nomex insulation paper is composed of 93% poly (m-phenylene isophthalamide) (PMIA) fibers and 7% inorganic substances based on elemental analysis. Using the thermogravimetry, it is found that the pyrolysis behaviors in nitrogen and air are similar below 770 K, with large discrepancies identified in the temperature range of 770–1073 K. The peak mass loss rate in air is 9 times higher than that in nitrogen. The kinetic analysis shows that the average activation energy (E ) in air is lower than that in nitrogen by 32% when the temperature is higher than 770 K, indicating a lower thermal stability. The PMIA fibers are found decomposing more seriously in air using SEM. Below 770 K, the functional groups of two atmospheres are mainly produced by the breakage of amide bonds and formation of aromatic nitrile. Unlike nitrogen, the organic substances in the solid residue are mostly oxidized at 1073 K in air. Consequently, the maximum productions of H2O, CO2 and CO in air are nearly 5 times higher than those of nitrogen, and the HCN generated during pyrolysis is further oxidized to NOx in air. Combining with the results of Py-GC/MS, it is inferred that the small molecules generated by the degradation of PMIA molecular chains, especially the benzene rings, will experience oxidization reactions in air atmosphere, with large amounts of H2O, CO2, CO and NOx produced. [ABSTRACT FROM AUTHOR]

The role of steel connections is essential in structural fire design and analysis for steel-framed composite structures. The current structural design provisions provide strength reduction factors of load-carrying members and their end-connection elements at elevated temperatures, based on small-scale experiments under uniform heating conditions. The realistic thermal and structural evolution in member connections, especially as part of full-scale floor assemblies exposed to a large compartment fire, has not been well characterized. A large compartment fire experiment was recently conducted on a 9.1 m by 6.1 m composite floor assembly as part of a two-story steel-framed building. The test assembly had a total of ten shear-tab (fin-plate) connections subjected to combined fire and mechanical loading. This paper presents the measured thermal response of these connections to fire and comparison with the corresponding Eurocode 3 predictions with two methods (1) incorporating the beam bottom flange temperature at midspan and (2) the section factor method. The results show that the Eurocode 3 methods conservatively predict the maximum temperature during heating and the cooling rate but overestimate the high-temperature strength of connections when estimated using the section factor method, showing that the Eurocode 3 simplified approaches are not meant to provide the details of the failure mode for connections. This study suggests that estimating the strength of connections using strength reduction factors may not guarantee a safe structural fire design. In addition, this paper estimated the total axial force (from slab and beam) at the composite connection via using the strain gauge measurements close to the column bases which were not exposed to fire. It suggests realistic axial load and rotational demand on the shear connection due to restraints to thermal elongation or contraction of supported members should be considered in future design guidance as should designing and detailing the connections for ductility to withstand the inelastic deformation demands during the heating and the cooling phases. [ABSTRACT FROM AUTHOR]

In recent years, with the development of DC transmission projects in China, the number of converter stations has increased. Fire accidents in converter stations have also become more frequent. Transformer insulating paperboard, as a typical combustible material in converter station equipment, poses a greater fire risk. So in this paper, flame spreading behaviors, including experimental visual characteristics, fire spreading rate, mass loss with time and mass loss rate, of transformer insulating paperboard with different thickness and different inclined angles are investigated. The results show that: (1) In downwards flame spread, that is, in the case of positive angle, the flame height and width gradually decrease with the increase of angle; in the case of negatively inclined angles, the flame length shows an increasing trend with the decrease of inclined angles, and the flame thickness gradually becomes thinner. (2) In upwards flame spread, that is, in the case of negative angle, the fire spreading rate of the insulating paperboard decreases sharply with the increase of the angle; In the case of a positively inclined angle, the change of flame spreading rate is not obvious with the increase of inclined angles as compared with the conditions in negative angles. The paperboard thickness also has a significant impact on the flame spreading rate, and the flame spreading rate will decrease significantly with the increase of paperboard thickness. (3) In upwards flame spread, the mass loss rate of insulating paperboard will decrease significantly with the increase of inclined angles; in downwards flame spread, the change of mass loss rate is not obvious with the increase of inclined angles as compared with those in condition of negative angles. At the same time, the mass loss rate will increase significantly with the increase of paperboard thickness. (4) The mass loss rate and fire spread rate of the insulating paperboard have a strong correlation with the flame length and the length of the pyrolysis zone. A heat transfer process model about characteristic length scale and mass loss rate is established. In order to simplify the model, a dimensionless relation about angle is defined to replace the feature length and to explore the relationship between angle and mass loss rate. Based on the inherent relationship between fire spread rate and mass loss rate, the relationship between fire spread rate and angle is found. And the result shows satisfactory agreement between the predictions and experimental results. [ABSTRACT FROM AUTHOR]

After over 30 years of fast economic development and massive construction of infrastructures, China now owns the largest total length of tunnels in the world. However, many tunnels are overloaded with a large traffic volume and vulnerable to fire accidents in operation. Once a fire occurs in the tunnel, the occupants face a dangerous and confined environment and need to evacuate before reaching untenable conditions. Failure in fire evacuation will cause severe injuries and casualties under high-temperature and toxic fire smoke, and many past fire accidents have taught us lessons. Driven by the need for tunnel fire safety in China, many new researches are conducted related to fire evacuation in tunnel environments including full-scale experiments, and new evacuation strategies are carried out with sophisticated tunnel designs and regulations. Hence, this work aims to review these latest developments and studies in China towards better and safer evacuation in tunnel fires. In specific, the paper summarized the evacuation issues in tunnel fires generally and pointed out the unique issues in China. Aiming these issues, the paper then introduced recent evacuation strategies and evacuation research in China respectively. Typical tunnel fire accidents and full-scale tunnel fire evacuation tests in China were discussed in detail as case studies. Detailed evacuation strategies and the exposed issues were analyzed in those tunnel fire accidents emphatically, while evacuation findings of human behavior such as evacuation choices and trajectories were presented according to several field tunnel fire evacuations conducted by the authors. Finally, we highlight the research advances and challenges of fire evacuation in tunnels, as well as the need and directions for future research. [ABSTRACT FROM AUTHOR]

At present, most of the previous work focused on the effects of crown bulk density, crown base height, and wind on the initiation and behaviors of crown fire using tree branches. However, very few investigations have been carried out related to the initiation and behaviors of crown fire using a real tree considering moisture content, crown height and tree flower. In this paper, a series of burning experiments are carried out using real trees to investigate the effects of moisture content, crown height and tree flower on initiation conditions from surface fire to crown fire and crown fire behaviors. The variables of two crown heights (1.0 m, 1.5 m), three crown moisture contents (45 ± 2%, 55 ± 2%, 65 ± 2%) and tree flowers are selected. The main conclusions are as follows: when the tree has the higher crown base height and the larger moisture content, the crown fire initiation success from surface fire decreases, while the existence of tree flowers tends to lead to initiation success of crown fire. The critical fireline intensity can be used to determine the initiation of crown fire from surface fire for conditions with the absence of tree flowers, whereas the critical value can not be applied to cases with the existence of tree flowers. Moreover, the lower moisture content and higher crown height are, the maximum values of the flame height, fire plume temperature, and radiation heat flux of crown fire are larger. Besides, when the tree is covered with tree flowers, the flame height, fire plume temperature, and radiation heat flux of crown fire increase significantly due to the increases of fuel load and flammability. This work can not only provide theoretical basis for crown fire, but also supply technical guidance for the prevention and extinguishment of crown fire. [ABSTRACT FROM AUTHOR]

A series of experiments and simulations were conducted to investigate the effect of lateral smoke exhaust in tunnel fires. A special phenomenon, plug-holing was observed. Combined with the exhaust vent size, heat release rate and exhaust velocity, the plug-holing was analyzed. The smaller the heat release rate and the greater the exhaust velocity will enhance the plug-holing. On the contrary, the narrow exhaust vent will help to inhibit the occurrence of plug-holing. At the same time, it is found that the Froude number criterion proposed by Hinkley is not suitable for lateral smoke exhaust system. In this paper, considering the difference between lateral smoke exhaust and ceiling smoke exhaust, the Froude number proposed by Hinkley is modified to determine the plug-holing in lateral smoke exhaust, and a new modified Froude number is established. The results show that when the new modified Froude number is greater than 2.5, the plug-holing of the lateral smoke exhaust will happen at the smoke layer. The new modified Froude number might be more accurate compared with the existing criteria to judge the occurrence of plug-holing for lateral smoke exhaust. [ABSTRACT FROM AUTHOR]

In recent years, electrical fires, which constitute the majority of fire incidents, have become a significant concern. This paper presents a quantitative evaluation of the research on electrical fires from 1993 to 2022, using literature measurement and visual analysis techniques. A total of 2915 publications were collected from the Web of Science database to review and analyze the research progress on electrical fires. In this investigation, the quantitative distribution of literature by year as well as the distributions of main source journals, countries and regions, institutions, and discipline categories were analyzed. Additionally, research hotspots were identified and the knowledge field was mapped using VOSviewer. The results indicated an exponential growth in the number of publications on electrical fires, with Ceramics International emerging as the most prolific journal, having published 79 papers and accounting for 2.5% of the total research. The most active countries in electrical fire research were found to be China, the United States, South Korea, India, Germany, France, and the United Kingdom, with Chinese publications having the most significant impact. The University of Science and Technology of China, Chinese Academy of Sciences, and Tsinghua University are the most productive institutions in the field of electrical fire research; their main research directions include electrical structure, electrical experiment simulation, insulating materials, battery fires, fire extinguishing technology, and detection methods. Further, we observed that the scope of research on electrical fires has expanded from the macro to micro level. Thematic analysis conducted in the last decade has revealed that battery fires and equipment materials have emerged as the primary focus of research in this field. These research findings offer a comprehensive overview of the evolution of research hotspots, which can assist researchers in quickly grasping the research frontiers as well as the overall situation. [ABSTRACT FROM AUTHOR]

The experimental study presented in this paper aimed to investigate the effects of bolt number and their pattern on the failure time of minimally fire-protected glulam beam bolted connections. Four full-size glulam beam-end connection configurations reinforced perpendicular to wood grain with self-tapping screws (STS) were experimentally tested under exposure to elevated temperatures that followed the CAN/ULC S101 (Standard methods of fire endurance tests of building construction and materials. Underwriters Laboratories of Canada, Fifth edition, Ottawa, Canada, 2019) standard fire time–temperature curve. All metal connecting components (i.e., bolt heads and nuts and steel plate edges) were fire protected using wood plugs and strips, respectively. Throughout the duration of fire tests, all specimens were subjected to monotonic load causing bending moment equivalent to the maximum moment design capacity of the weakest unreinforced connection configuration. Fire test results show that the failure time of all four proposed wood–steel–wood connection configurations surpassed the 45-min mark, which is the minimum prescribed fire resistance rating for timber connections in applicable codes, with the two configurations that employed six bolts sustained the applied load for more than 60 min in standard fire conditions. Increasing the number of bolts from four to six enhanced the failure time of the proposed connection configurations with time increments more than those due to changing the bolt pattern. Most importantly, test results confirm that reinforcing the connections with STS fully curtailed wood splitting and averted row shear failure that is frequently encountered in similar but unreinforced connection configurations. [ABSTRACT FROM AUTHOR]

The fracture behavior of welding material at elevated temperatures can significantly affect the performance of steel welded connections in fires. Therefore, this paper investigates the fracture behavior and fracture model of welding material in steel welded connections exposed to elevated temperatures up to 700°C. Firstly, using the standard tension test data and numerical analysis method, the true stress–strain model of E7018 welding materials at elevated temperatures was derived for fracture prediction of steel welded connections. The fracture parameters of the welding materials at elevated temperatures in tension and shear were calibrated from the results of the standard tension test and longitudinal fillet-welded connection tension test, respectively. The 2D fracture models of welds at elevated temperatures were developed considering the relationship between stress triaxiality and equivalent plastic strain at fracture. The 3D fracture models of welds at elevated temperatures were then established from the 2D fracture model by considering the effect of Lode angle parameters in tension and shear. The 3D fracture models of welds were validated against the tension tests on the fillet welded connections at elevated temperatures under different load angles including 0°, 45°, and 90°. Finally, the fracture model as the function of temperature, stress triaxiality, Lode angle parameter, and plastic strain at fracture was proposed for E7018 welding material. According to the results, the welding material demonstrates ductile fracture behavior at elevated temperatures. The developed 3D fracture model can reasonably predict the fracture behavior of the welding material in steel welded connections at elevated temperatures. [ABSTRACT FROM AUTHOR]

This paper presents the comparative fire performance of reinforced concrete (RC) beams made of concretes with different strengths by undertaking fire resistance tests. Four RC beams made of normal strength concrete (NSC), high strength concrete (HSC), and ultra-high performance concrete (UHPC) with different fiber combinations, were subjected to structural loading and tested under fire conditions. Results from the fire resistance tests show that UHPC beams undergo severe fire-induced spalling and exhibit lower fire resistance as compared to HSC and NSC beams. Additionally, the inclusion of polypropylene (PP) fibers in UHPC beams aids in reducing spalling and increasing fire resistance in UHPC beams. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study that investigates the effect of fiber dimension on preventing spalling of ultra-high-performance concrete (UHPC). UHPCs with different dimensions of polypropylene (PP) fibers were prepared for permeability test at different temperatures and spalling test under ISO834 fire curve. Scanning electron microscope (SEM) observation was also conducted focusing on the fiber of a UHPC sample at the same location after it was subjected to elevated temperatures. The results of permeability tests and spalling tests showed that longer fibers of 12 mm and 18 mm and finer fibers of 28 μm and 33 μm were more beneficial for increasing the permeability of UHPC at high temperature, resulting in higher effectiveness on spalling prevention. Permeability measurements indicated a significant increase occurred at 150°C regardless of fiber dimensions; this increase plays an important role in spalling prevention. SEM results further testify that this increase can be attributed to the formation of microcracks caused by expansion of PP fibers. An aspect ratio of 300 is recommend for spalling prevention of UHPC, when 3 kg/m3 of PP fibers are used. [ABSTRACT FROM AUTHOR]

This paper studies the fire response of a frame with Concrete-Filled Steel Tube Columns (ST-RC column-RC beam). The structure was modeled in the finite element analysis platform ABAQUS, and the its validity was verified against experimental data. The model was subjected to fire and vertical load and the failure mode, deformation, internal forces, stresses, and fire resistance, and the factors that influence the fire resistance were analyzed. Two failure modes were detected: in the one, the beam of the frame is involved, and in the other, beam and column simultaneously fail. Under the combined action of fire and load, the bending moment of the beam and column changes significantly. The parameters that have a great influence on the fire resistance of the structure are the column and beam load ratios, beam to column linear stiffness ratio, column slenderness ratio, column section size, core area ratio of column section, and compressive strength of concrete around column. Considering the above main factors, a simplified calculation formula for the fire resistance of this frame is provided. This research can provide reference for the design of this kind of frame structure in practical engineering. [ABSTRACT FROM AUTHOR]

Hybrid fire testing is a testing method for structures on fire based on a substructuring method. A complete structure is divided in two substructures, one in a fire test laboratory (physical substructure), and one numerically simulated (numerical substructure). In fire engineering, some hybrid fire tests have been successfully performed in the last decades, but as the method is still in its infancy, these hybrid tests were limited to one-degree-of-freedom tests. The paper presents the first successful multi-degree-of-freedom hybrid test performed in fire engineering. The physical substructure is a steel column with an axial displacement and rotations at the ends controlled by electric jacks. The numerical substructure is a non-linear 2D plane frame structure modelled in SAFIR®. The equations of the algorithm, the experimental setup, the testing process, and the results are presented. [ABSTRACT FROM AUTHOR]

The catastrophic events of September 11, 2001, stand out as a major motivation for research on improving the understanding of structural behaviour in fire. These events included the first complete collapse of a tall steel framed structure solely due to fire. World Trade Center 7 (WTC7) was a 47-storey office building within the WTC complex that collapsed due to a fire initiated by debris from the collapse of WTC1. In the following years, detailed investigations were carried out by expert teams to pinpoint the cause of the progressive failure of WTC7. Each of the expert teams analysed the fire and structure and made varying conclusions with regards to the mechanisms responsible for initiating and propagating the collapse of the building. This paper revisits the collapse of WTC7 and its investigation, and then explores the hypothesis that a potential hydrocarbon fire may have compromised the large transfer structure within the mechanical space of the building. This is done via two OpenSees finite element models. The first model explores the thermomechanical response of the mechanical floors to a potential diesel fire, and the second investigates the response of the structure to a failure caused by that fire. The outcome of the analyses shows that it is feasible that a mechanical room fire could lead to a failure in the transfer structure, which would then result in the loss of support to at least two columns within the building core. The failure of these columns may unbrace the eastern-most core columns and precipitate in the failure of the structure as observed on 9/11. [ABSTRACT FROM AUTHOR]

This paper presents the performance-based fire safety analysis of steel structures of padel-center built in Nokia, Finland. The analyses are conducted using advanced calculation models (fire simulations using Fire Dynamics Simulator, FDS, and finite element method, FEM, based analyses of the steel frames in elevated temperatures using SAFIR software, including joint analysis) in support with less sophisticated models (critical temperatures of steel members). The following localized fire scenarios are studied: lounge area furniture fire (4 sofas), sporting equipment fire (10 sporting bags filled with flammable clothing), fire during maintenance (scissor lift fire with miscellaneous temporary fire load) and a fire on HVAC balcony near the trusses. The aim of the paper is showcase recent developments in design processes and methods that are in practical use today in performance-based fire design (PBD), to demonstrate that relatively extensive performance-based studies can be (commercially) viable also in relatively small and mundane steel buildings, and to present a fairly robust framework for PBD of similar steel structures. As a result of the performance-based design, most of the steel structures in the case building could be constructed without fire protection, but some critical structures were identified and protected to class R30. The proposed design was approved by the local municipal authorities. [ABSTRACT FROM AUTHOR]

Concrete-filled hollow section (CFHS) columns with a solid steel core have gained popularity in the construction of tall buildings due to their robust load-bearing capacity, slender design, ease of prefabrication, and exceptional structural fire resistance. In this research paper, we introduce an innovative approach aimed at enhancing the structural performance of these columns. Our method involves replacing the solid steel core with high-strength bar bundles and substituting concrete with grout to achieve superior fire resistance. These modified columns are referred to as "bar-bundle columns." The paper presents the results of extensive fire tests conducted on three bar-bundle columns, each with different bar-bundle sizes, quantities, and configurations. Additionally, we determine the temperature-dependent material properties of the high-strength steel used for reinforcing bars and the thermal properties of the grout used as a filler through standard experimental tests, which are crucial for numerical simulations. An advanced nonlinear finite element model is describe which is capable of predicting the fire behavior of bar-bundle columns. Finally, this numerical model is employed to conduct parametric analyses and propose a simplified design model for bar-bundle columns under fire conditions.Our findings indicate that the bar-bundle configuration and using grout as a filler significantly delays the heating of the steel core, resulting in enhanced fire resistance when compared to CFHS columns with a solid steel core. The simplified method proposed in this study can be used to estimate the fire resistance of slender bar bundles, but further experimental testing could further refine and improve its accuracy. [ABSTRACT FROM AUTHOR]

Sprinkler system can be very reliable and effective way to reduce fire risks in buildings if maintained properly. When the sprinkler system operates as designed, the temperatures affecting the load-bearing structures are often relatively low and the structural resistance is typically not compromised. Holistic Structural Fire Engineering (SFE) provides an opportunity to take active systems, like sprinklers, into account in the design. However, it is important to ensure that if the sprinkler system does not operate as designed, the consequences are still tolerable. Even though there are options to account sprinkler system in SFE, there is a lack of consistent guideline (at least in Finland). This can lead to totally different structural fire design and safety in similar buildings, depending on the interpretation and assumptions made. This paper presents a framework to take the effect of the sprinkler system consistently into account in SFE. The framework is based on Finland's fire regulations and on experience of multiple projects. Two case-examples, where this framework has been applied are presented in the paper. [ABSTRACT FROM AUTHOR]

Slim-floor-type of steel-timber hybrid floor systems which use steel beams contained within the depth of the cross-laminated timber (CLT) floor slab offer many benefits, but there is still very little research available on the fire resistance performance of these systems. In the study presented in this paper two furnace tests and numerical simulations have been conducted to investigate the thermal profiles of the steel member and CLT slabs and to obtain information on the temperature development and charring of the hybrid beam section when it is exposed to standard fire conditions. Also, the effects of intumescent fire protection on temperatures and charring performance were investigated. Numerical 2D thermal simulations for unprotected and protected cases were conducted using SAFIR software, and the agreement between experiments and numerical-analysis predictions were in general very good. The results show that intumescent protection reduces the temperatures of the steel and CLT components as well as charring depth significantly, and the start of charring at CLT slab support may be delayed if intumescent paint protection thicker than that required for the load bearing steel member is used. The result also showed that CLT temperatures exceed 100°C already in the early stages of the fire which decrease the strength and stiffness properties of CLT much before the start of charring. Therefore, the fire design of the CLT slab support should not only consider the char depth and residual cross-section analysis but also the reduction in strength. [ABSTRACT FROM AUTHOR]

The traditional storage method of fire accident cases is mainly in the form of text, and it is difficult to effectively conduct comprehensive analysis due to the limited ability to display key information and fire knowledge. In this paper, a structured storage form of building fire cases was proposed based on knowledge graph, which can comprehensively describe and visualize the fire causes, the dynamic fire development process and evacuation process. It enables readers to get information and knowledge from building fire cases intuitively, and supports the comprehensive analysis for building fire prevention strategies. The knowledge graphs are constructed for two common building types (residential and public buildings), and have the capacity to reflect the dynamic development law of fires from ignition to spread in different buildings. Meanwhile, as the occupants' evacuation is the first concern when a fire occurs, the knowledge graphs also visualize the relationship among various conditions in the evacuation process. Different application scenarios are displayed in the paper, including case query, root-cause analysis and consequence forecasting, which shows the advantages and applicability of building fire knowledge graph. [ABSTRACT FROM AUTHOR]

The main objective of this paper is to use the residual strength theory to study the probability of a domino effect accident occurring following the explosion of a spherical tank. We build a novel domino effect accident probability model, using Monte Carlo methods to simulate the ejection of debris. At the same time, the velocity and velocity distribution of fragments ejecting from the upper and lower parts of the explosive spherical tank are obtained. Finally, the relationship between the volume of the exploding spherical tank and the target, the crater Angle (ψ0 and ϕ0) of debris impacting the target, the probability of target destruction and the risk of domino effect accidents are considered. The results show that the maximum speed of debris from the lower part of a spherical tank exceeds that from its upper part, and the hazard associated with the debris from the lower part cannot be ignored. With the same target volume and spacing, the probability of a domino effect accident caused by projectile debris from the upper half of an exploding spherical tank is higher than that from the lower half. As theψ0 value increases, the probability of target failure gradually decreases, and as the ϕ0 value decreases, the probability of target failure also gradually decreases. Moreover, with changes in ψ0 and ϕ0, the probabilities of destruction and the occurrence of a domino effect accident significantly change. The results of this paper can provide guidance for the risk assessment of oil and gas storage tanks. [ABSTRACT FROM AUTHOR]

China Power Grid is actively building a new energy-based ultra-high voltage grid system. Therefore, the researches on fire safety of power grid are of great importance. This paper firstly investigates the fire accident characteristics in the substation system. With the focuses on the transformer oil fires, the early detection and early warning, modification, fire monitoring and extinguishing systems of transformer oil are reviewed. It is found that the researches on flowing and jet fires should be reinforced while modified oil and pyrolysis gas detection can be applied for reducing the fire probability. Secondly, the fire risks and characteristics of cables are summarized for the transmission and distribution lines, and the methods of early warning, fire prevention and rescue are analyzed. For the wildfire threatening the transmission and distribution cables, the characteristics of wildfire and corresponding firefighting methods are reviewed. The water mist and liquid nitrogen are identified as the most effective ways of extinguishing cable fires and advanced fire detection and long-range drone fire extinguishing technologies should be improved for wildfires. Finally, the thermal runaway mechanism and fire characteristics of LIB in the energy storage system are summarized, and the difficulties in fire extinguishing are discussed. The application of the existing fire detection system in the field of LIB is proposed, and the early warning indicators for intelligent fire protection are introduced. In the future, the intelligent fire protection systems will improve the safety of energy storage systems, and efficient test platforms and reliable test standards will continue to be demanded to reduce the likelihood of thermal runaway and fire severity. [ABSTRACT FROM AUTHOR]

This paper is focused on the evolution of the vertical temperature profile of spilled plume originated from a compartment-facade fire under the conditions of different horizontal projection lengths. A series of reduced scale experiments were carried out in a 1:8 cubic fire compartment model with a single window at the center of the compartment's side wall. A vertical facade wall was attached to the compartment window, and a horizontal projection was installed at the level of window's top as the representative of a fire protection cornice in a real building. In the experiments, by varying the length of horizontal projection, the total heat release rate as well as the window sizes, the vertical temperature recorded by a series of thermocouples along the centerline of facade wall was analyzed. Results showed that, with the presence of horizontal projection, especially for a longer projection, the temperature of the spilled plume was reduced significantly, which is beneficial to fire protection in high-rise buildings. Meanwhile, two different regions were observed due to the flame retrieving effect to the facade wall, and therefore, the temperature would first increase and then decrease in the vertical direction, which is completely different from the results obtained without the horizontal projections. A critical vertical height with the highest temperature was discovered, and regarded as the new reference point. On this basis, a new normalized vertical height based upon the reference point and a new virtual origin were brought up. Finally, new correlations of vertical temperature with the updated normalized vertical height were proposed within the buoyancy plume region. This is a novel investigation for the spilled flow dynamics from a compartment-facade fire with horizontal projection conditions, and has great significance for improving the fire-fighting capabilities for a building in practice. For a compartment-facade fire, two new regions with a low temperature zone are newly discovered at the presence of horizontal projection, and new correlations of vertical temperature decay are discussed. [ABSTRACT FROM AUTHOR]

In the past three decades, fire engineering has experienced fast development worldwide. Fire regulations for building industry were moved from prescriptive description to performance-based specification. This trend started in the UK in the 1980s and spread to other western countries. Hong Kong closely followed the UK development and adopted the approach of performance-based design (PBD) for the Hong Kong International Airport and MTR stations in the early 1990s. The Government of Hong Kong SAR formally recognised the PBD approach in the prescriptive codes of practice in the mid-1990s and developed the performance-based code (PBC) in the 2000s. This PBC was promulgated in 2011. The evolution in fire engineering impacted the fire community in Mainland China. The State Key Laboratory of Fire Science (SKLFS) was established in University of Science and Technology of China (USTC) in 1991. Then fire science and fire engineering stepped into the fast development track. The building industry in Mainland China started to adopt the PBD approach in the early 2000s for the significant developments including large airport terminals, railway and metro stations, super high-rise buildings, and mega commercial centres. However, a structured PBC system is not available within the regulatory framework to date. Adoption of PBD approach is slowing down in recent years. This paper presents a review of fire engineering development in Hong Kong and Mainland China. The review focuses on the development of the PBC in Hong Kong, and the PBD approach and fire research in Mainland China in the past 30 years. [ABSTRACT FROM AUTHOR]

Kawagoe's Law is an essential correlation in compartment fire research, which defines the relationship between the ventilation factor and maximum fuel burning of the compartment. Although this law has been widely used, there is still a lack of numerical validation and knowledge on the limiting conditions of its application. In this paper, a numerical study is conducted under full-scale compartment fire with different opening sizes and gas fuel supply rates using the LES model for validating Kawagoe's Law. The mass flow rate of inflow through the opening and the indoor heat release rate is focused during the numerical validation. Numerical results show that the inflow rate and indoor heat release rate comply well with Kawagoe's Law under ordinary openings with a small aspect ratio. However, Kawagoe's Law becomes less valid for openings with large aspect ratios and small-gap openings. The jet flame was observed in the case of openings with large aspect ratios under a high fuel supply rate. For compartment fires with small gaps, a breathing process, i.e., the periodical suppression and revitalization of the fire, is modeled. This work provides practical guidance for modeling compartment fires and paving the way for constructing a numerical compartment fire database. [ABSTRACT FROM AUTHOR]

This document is a summary of a special issue of the journal Fire Technology, titled "Structures in Fire 2022." The issue focuses on the research area of structures in fire, which is important for the safety and resilience of engineering infrastructures and urban environments. The special issue includes 24 papers that were selected from the 12th International Conference on Structures in Fire (SiF2022). The papers cover a range of topics, including the performance of structural members in fires, fire safety of timber members, system-level structural response to fire, and the incorporation of sprinkler systems in structural fire evaluation. The research presented in this special issue contributes to enhancing our knowledge of structures in fire. [Extracted from the article]

So far too long, people have been working hard to develop fire prevention measures to deal with lithium ion battery (LIB) fires. LIB fires have a high calorific value, a rapid burning and spread speed and a high risk of re-ignition and explosion. Under thermal runaway, LIB fires develop from the inside out, preventing fire extinguishing agents from entering the interior of LIB, thus resulting in low extinguishing efficiency or even failure of the extinguishing agents. Based on the principle of 'isolation and stifling', fire-blocking blanket can effectively inhibit the spread of fire, suppress the combustion intensity and reduce the smoke emission. This paper digs into the detailed performance requirements of fire blanket to block LIB fires. By conducting laboratory tests to mimic LIB fires, the candidate materials including fiber materials, woven textile and woven fabrics with organic coatings are systematically investigated. Performance of the materials are evaluated, including fire resistance, thermal insulation, tensile strength at break and blast resistance, respectively. The testing results help to screen out the best material for LIB fire blanket, and high-silica glass fiber coated by polyurethane has the best thermal and mechanical properties among all materials tested. This paper also presents a three-layer structured design of blanket, which can pass all the tests proposed. [ABSTRACT FROM AUTHOR]

This paper presents two facets of rationalizing natural fires in concrete compartments for structural fire safety. The paper proposes the rate of fire growth corresponding to the maximum possible peak temperature in a compartment, followed by an equation to estimate the equivalent severity between the standard and a natural fire using an energy-based approach. Standard fire curves, applied universally for all design conditions may over- or under-predict real compartment fires. Meanwhile, a full-fledged performance-based design is neither practical nor straightforward to employ in every design situation. The Eurocode parametric temperature–time curves enable engineers to account for specific compartment characteristics, including compartment geometry, building materials, fuel load, and ventilation. Given that different structural fire safety design approaches entail varying levels of complexity, this paper presents simple methods to estimate the worst-scenario compartment fire characteristics. Additionally, fire ratings are established only using standard fire curves, necessitating a scientific means of determining an equivalent severity between natural and standard fires. The energy-equivalence approach used in this paper to establish an equivalent fire severity yields more consistent results than traditional equivalent fire severity methods and empirical formulae for concrete compartments. The proposed equations are developed using simulations of compartment fires and provide insights into the ventilation characteristics that result in the worst-case scenario for both the rate of fire growth and the equivalent time. [ABSTRACT FROM AUTHOR]

This paper presents the parametric study of a simple aluminium frame made of EN 6082 T6 aluminium alloy exposed to transient heating. The heating rates up to 5 ∘ C/min were used in numerical calculations to simulate fire protection essential in modern structures. The main focus of the study was to determine the influence of creep strain on the reduction of the load-bearing capacity of the main columns in a typical structure. A significant impact of creep strain on the critical temperature and failure time is given with a total of 60 numerical simulations with the comparison between creep and the creep-free model. The results have shown that for the applied creep model, the failure of the column due to buckling was accelerated with the developed creep strain for 28% than without taking creep into account for the middle column. For faster heating rates and other specific columns, the given failure time gradually decreases but still with significant impact on the overall load-bearing capacity. Numerical calculations were carried out in ANSYS 16.2 software with the use of the Modified Time Hardening creep model whose parameters were obtained within the previous studies. [ABSTRACT FROM AUTHOR]

In this paper, a new gram scale experiment with well characterised boundary conditions is proposed for pyrolysis experiments. The set-up consists of a tube furnace, based on ISO19700, with a newly designed concept for a balance within the oven, allowing for online mass loss measurements. Samples with a length up to 50 cm can be investigated in this apparatus. The oven allows for experiments at fixed temperatures or at fixed heating rates, under controlled atmosphere, w.r.t. gas composition and flow rate. A thorough characterisation of the set-up is presented, including aspects like reproducibility of the heating rate or the precision of the balance. The functionality of the balance has been demonstrated with calcium carbonate (CaCO 3 ) experiments. This material was chosen because it decomposes in a single reaction, which only releases CO 2 . This allows for comparison between the mass loss rate of the balance and the CO 2 production rate, measured by a gas analyser. Results for two different heating rates: 3 K/min and 5 K/min and for different masses (25 g and 8.5 g) are presented. The two measurement methods are in excellent agreement. Finally, the data obtained from the new experimental set-up is compared to results from thermogravimetric analyser (TGA) experiments. [ABSTRACT FROM AUTHOR]

Densified wood (DW) is a carbon-negative and energy-saving structural material with promising applications in high-rise timber buildings. However, its fire safety issues restrict its applications. In this paper, a bio-material, phytic acid, based flame retardant PPBNOH was prepared to improve the flame retardancy of DW. The structure characteristics, thermal stability, flammability, combustion behavior and mechanical performance of flame-retardant DW (PPBNOH/DW) were studied. Results show that the decomposition of PPBNOH catalyzes char formation and enhances thermal stability. Thus, PPBNOH/DW has a 57% reduced peak mass loss rate and a 27.9% increased char yield. Both the wood dense structure and PPBNOH catalyzation synergistically promote the formation of phosphorus-containing, crosslinked and aromatic char during wood combustion, which hinders heat/mass transfers and enhances flame retardancy. Thus, PPBNOH/DW has a 53.2% limiting oxygen index, a V-0 rating of UL-94 test. It presents delayed ignition time, reduced heat release characteristics and lower heat of combustion (5.37 MJ kg−1) in the cone calorimeter test. BNOH improves the smoke suppression performance of PPBNOH/DW with a 38.6% reduced total smoke production. The compatible and thermally insulating char also enhances the high-temperature heating resistance of PPBNOH/DW as it has the highest remaining mechanical strengths after heating. [ABSTRACT FROM AUTHOR]

This study employs a combination of theoretical analysis, Similarity simulation, and computational fluid dynamics (CFD) to examine the airflow caused by the stack effect under different leakage conditions in high-rise buildings and the transport of fire smoke. Building on previous research, we quantify the leakage area using a formula and classify it into two categories, "tight" and "leaky." Based on the analysis results, we conduct a similarity simulation experiment in a small-scale high-rise building experimental platform with a height of 5.2 m to create a certain size of leakage area at the bottom and record carbon monoxide concentration at different locations and times. The obtained result is then compared with the numerical simulation result, and the similarity simulation results match well with the numerical simulation results. The findings demonstrate that increasing the leakage area accelerates the transport of smoke due to the stack effect, particularly at higher floors. This paper also discusses strategies to impede smoke diffusion, providing valuable references for the safety design of high-rise buildings. [ABSTRACT FROM AUTHOR]

This paper is aimed at studying the down-reaching flame behaviors of tank fires with large ullage heights. Experiments were first conducted using a gas burner in a transparent quartz glass cylinder to simulate the large ullage and the experimental data was used to validate the computational fluid dynamics (CFD) model. Subsequently the effects of ullage height, fuel velocity and burner diameter on the flame behaviors were examined systematically. Both experimental and numerical results showed that, for lower fuel velocities, the down-reaching flame height (hdown) is restricted by the ullage height. As the fuel velocity continues to increase exceeding a critical value, independent of the ullage height, hdown starts to decrease. For a given fuel velocity, hdown increases with an increase of the burner diameter owing to enhanced air entrainment. A detailed analysis of the flow field and oxygen concentration inside the tank at the steady burning stage was also carried out. Based on the numerical results and dimensionless analysis, a piecewise function was proposed to predict the down-reaching flame height and validated against the experimental data. [ABSTRACT FROM AUTHOR]

High-strength steel has been extensively used in numerous structures or high-rise buildings because of its high strength, ductility, and weldability. However, high-strength steel structures are vulnerable to fire hazards, so the ability to predict structural behavior is crucial in structural fire safety design. Creep behavior is one of the primary factors influencing the response of steel at high temperatures. This paper presents numerical studies using the fire dynamics simulator (FDS) and finite element method (FEM) coupling models to predict the structural behavior of a protected beam with a cavity for H-SA700 high-strength steel at elevated temperatures, including the creep effect. A comparison between simulation and experiment results demonstrates the validity of the process. In detail, based on a set of tensile tests conducted at six constant temperatures between 23°C and 600°C, the creep model is proposed. Subsequently, because creep is temperature-dependent, the heat transfer model used to predict the temperature distribution of the steel is developed. The effect of the partially damaged protection cover is discussed. Finally, it is found that with the temperature distribution from FDS-FEM integration and the proposed creep models, the collapse time of the beam can be defined. This study provides a practical approach for developing the creep model without creep tests and applying it to complex structures during fires. [ABSTRACT FROM AUTHOR]

Exploring fire resistance of high strength steel end-plate connections is one of the key technical bases for fire resistance design and fire safety assessment of high strength steel structures. Numerical simulation and parameter analyses of high strength Q690 steel flush end-plates will contribute to a reasonable design of high strength flush end-plate connections. In this paper, a finite element model of high strength steel flush end-plate connection considering thermal creep effect was established and validated by experimental results. The thermal creep finite element model can simulate accurately heat performance, failure modes and deformations of high strength flush end-plate connections at elevated temperatures. The increase of axial compression ratio has little effect on rotation, deflection, failure time, critical temperature, and critical rotation with elevated temperatures. The increase of bending moment ratio has little effect on the development trend of rotation and deflection. Proper increase of thickness of the end-plate can improve failure time and critical rotation, and the increase range is within 7% and 36% respectively. Proper increase of diameter of bolt can improve failure time, critical temperature, and critical rotation to a certain extent, and the increase range is within 10%, 6% and 27% respectively. Proper increases of thickness of the end-plate and diameter of bolt will improve the fire resistance of flush end-plate connection. [ABSTRACT FROM AUTHOR]

Eurocode-2 (EC2) empirical equation for fire resistance of RC columns is very sensitive to the value of column capacity at normal temperature conditions N Rd . Techniques to determine N Rd accurately for eccentric slender columns are difficult and computationally demanding; thus, adopting simplifications leads to unsatisfactory results in many column cases. Another shortcoming of EC2 equation is that it does not include an explicit term regarding the effect of load eccentricity on fire resistance. In this paper, a simplified method, as an attempt to overcome EC2 method defects, is developed to determine the fire resistance of RC columns using fire-resistance-column-curves. A rational numerical model is used to analyze various series of RC columns with different geometric, material, and loading properties at elevated temperatures. The results of the numerical study are utilized to construct different fire-resistance-column-curves from which simplified design equations are developed to predict the fire resistance of fixed- and pinned-end RC columns. The validity of the method is established with the aid of experimental data and it was found that in most cases, there is good agreement between assessed and test columns. It was also found that the proposed equations provide sufficiently safe predictions when appropriate material safety factors are adopted. The applicability of the proposed method to fire resistance design of RC columns is illustrated through numerical examples. [ABSTRACT FROM AUTHOR]

The mechanical material behavior of mild steels is reversible in the cooling phase of natural fires, which is proven by experimental evidence. For the material behavior of high-strength steels during cooling, no results are yet available. The paper provides the first comprehensive test program on the constitutive material behavior of high-strength steels S690QL and S960QL as well as mild steel S355 J2 + N in the case of natural fires. It is elaborated that the mechanical material behavior of high-strength steels in the cooling phase differs from the behavior in the heating phase and is not reversible due to phase changes of the microstructure. A constitutive material model for structural fire design purposes is developed on the basis of experimental data and the soundness and reliability of the model are proven by a statistical study that systematically evaluates the deviation of the model prediction from the test data. [ABSTRACT FROM AUTHOR]

The use of advanced materials, such as ultra-high-performance concrete (UHPC), and slender cross-sectional shapes in bridge girders can result in high susceptibility to shear failure during fire exposure. Shear limit state is usually not considered in fire design, which can be a major risk for I-shaped girders with slender webs. This paper presents the development of an approach to evaluate the shear capacity of UHPC bridge girders during fire through extension of room temperature capacity equations to elevated temperatures. Four types of standard AASHTO concrete bridge girders are analyzed under both standard and hydrocarbon fire scenarios. The output results are utilized to evaluate the progression of temperatures and deflections throughout fire exposure, as well as estimate degradation in flexural and shear capacities. Results show that the fire resistance of UHPC bridge girders are significantly affected by fire severity and concrete mass and that these factors should be taken into consideration in fire design of UHPC bridge girders. [ABSTRACT FROM AUTHOR]

Risk-based design and assessment methods are gaining popularity in performance-based structural fire engineering. These methods usually start by defining a set of hazard scenarios to use as analysis inputs. This approach, proven highly effective for other hazard types such as earthquakes, may not be optimal for fire safety design. Indeed, the strong coupling between the fire phenomenon and structural features enables an ad-hoc design variable selection (and/or optimisation) to reduce fire intensity, making fire scenarios additional design outputs. In addition, such a coupling effect implies that fire scenarios maximising consequences are structure specific. Building on these considerations, this paper discusses the limitations that arise at different analysis steps (i.e., fire-scenario and intensity treatment, identifying fire intensity measures, probabilistic fire hazard analysis, developing fire fragility models, and risk calculation) when using conventional risk-based approaches for design purposes. Furthermore, it compares such approaches with a fire safety design methodology (the Consequence-oriented Fire intensity Optimisation, CFO, approach) that addresses the identified limitations. The potential benefits of integrating the two approaches are also discussed. Finally, the fire design of a simplified steel-girder bridge is introduced as an illustrative example, comparing the consequence metrics and design updating strategies resulting from the two approaches. [ABSTRACT FROM AUTHOR]

A simple design method typically applies a Fire Resistance Rating (FRR) to structural components in isolation based on their performance in the fire test. This approach naturally assumes that the interaction between these components does not degrade their fire performance. To assess the reliability of this assumption, this paper numerically investigated the fire performance of continuous steel columns, incorporating the effects coming from connected steel beams and composite slabs. A 3-step numerical validation, using ABAQUS and following a recommended general simulation process, confirmed the numerical model's accuracy for this research through agreement with experimental tests. The simulation results founded that the well-designed interior column subassemblage, T4-90, failed to reach the designed FRR. This is due to compression coming from the continuous bending beam through the beam bottom flange, significantly weakening the column performance. Rib stiffeners between column flanges are proposed to enhance resistance to contact forces from beam flanges during severe fires. However, the simulation found that the steel columns with rib stiffeners might fail immediately after reaching the FRR. Thus, this research introduced the concept of 'reserve fire resistance' (authentic fire resistance to FRR) to evaluate structural steel elements' resilience to fires exceeding the specified FRR, aligning with the concept of reserve capacity of structural resilience to earthquakes. Based on this concept, new limiting temperature design equations were proposed and validated for steel columns derived from their performance, which yielded an average reserve fire resistance of 1.30 herein. [ABSTRACT FROM AUTHOR]

Using bolts as shear connectors of the steel–concrete composite beams enables prefabricated assembly and makes it possible to demountable and reuse the prefabricated components. However, studies on the fire resistance of prefabricated demountable composite beams (PDCBs) connected by bolts are limited. In this paper, four full-scale fire resistance tests were conducted to investigate the fire resistance of PDCBs connected by shear bolts with profiled sheet ribs parallel to the steel beam. Experimental observations, heating curves, deformation curves, and critical temperatures of specimens were obtained through fire-resistant tests. Test results show that the shear failure of bolted connectors occurred in the partially connected PDCBs instead of in the fully connected ones. Under the same load ratio, the fire resistance limit of PDCBs with fire protection was 4.4 times that of PDCBs without fire protection. The temperatures of the upper flanges of the steel beams in the PDCBs were overestimated by the existing codes. Moreover, numerical heat transfer analysis was carried out to investigate the effect of concrete slab thickness, concrete moisture content and steel beam upper flange dimensions on the temperature distribution of the steel beam upper flange. Finally, based on the results, relevant recommendations are made for the method of calculating the temperature of the steel beam upper flange in the PDCBs. [ABSTRACT FROM AUTHOR]

Global fire performance of structures in fire is proven to be more advantageous in many cases of engineering practice than the prescriptive fire resistance based on isolated structural member testing. Hybrid fire simulation (HFS) is a novel well-suited method trending in recent years for analysis of global performance of structures in fire. In the principles of this method, the part of a structure which has unknown behavior or is uncertain to be numerically modeled (subjected to fire) would be physically tested, while the rest of the structure is numerically simulated. HFS method enables capturing the beneficial interaction mechanisms evolving between fire-exposed structural members and the adjacent cooler substructure. Due to the continuous temperature increase in a fire test and the existing thermal inertia as well as the rate- and temperature-dependent material behavior of structures exposed to fire, a real-time performance in hybrid fire simulation counts as a necessity. This challenge is more critical for hybrid fire simulations with higher applied heating rates relevant to structural fire engineering. Within scope of this paper, (a) a robust and rigorous approach for real-time HFS is presented; (b) a series of proof-of-concept studies of different hybrid fire simulations with various applied heating rates are carried out for a thermomechanical benchmark problem; (c) the important results of four representative hybrid fire simulations with relevant heating rates to structural fire engineering are discussed; (d) the importance of an appropriate calculation method for stiffness update of the fire-exposed structural member over HFS procedure is highlighted, and e) the precision and accuracy of the applied HFS approach with respect to interface error and real-time degree are evidenced. [ABSTRACT FROM AUTHOR]

The paper describes the outcomes of the analysis of a steel braced frame protected with spray-applied fire resistive material and subjected to fires following earthquake (FFE). Nonlinear time-history analyses were performed in order to evaluate the seismic response. Then, the post-earthquake fire ignitions within selected compartments were considered based on the damage suffered by the structure, which was estimated according to the inter-storey drift ratio and floor acceleration. Natural fire curves were determined by means of zone models. Thus, compartmentation and opening characteristics were included in the analysis. Finally, thermomechanical analyses were completed and failure criteria based on the column and beam displacement and rate of displacement were investigated. The results of the probabilistic analyses were used to produce fragility functions to evaluate the probability of exceeding a limit state conditioned on an intensity measure in the context of FFE. [ABSTRACT FROM AUTHOR]

In October 2019, the largest fire in a commercial building in New Zealand since 1947 burned for over ten days through the roof and upper floor of the 120 m wide × 100 m long New Zealand International Convention Centre, which was under construction and nearing completion at the time. The steel composite and reinforced concrete framed building features five storeys above grade of structural steel framing with composite floors, comprising heavy, intricate steel work that was impacted by the fire. The main steel structure performed very well in response to fire exposure ranging from low to severe, with minimal damage and distortion to the heavy steel roof members in general, considering the severity of the fire. Secondary steel angles, tubular steel, and wide-flange members at the roof elevation were locally more heavily distorted. A very detailed post-fire evaluation of the structure was carried out, comprising mapping of the fire effects, deflections, metallurgical changes, extensive numerical modelling, and full scale in-situ experimental testing. The outcome resulted in retention of over 95% of the total roof steelwork (2500 tonnes). This paper provides an overview of the fire and the key steps involved in the post-fire structural evaluation of this unique fire case history. [ABSTRACT FROM AUTHOR]

To understand sandwich panel behaviour under fire, expensive full-scale tests, or potentially more efficient fire-structure simulations can be carried out. However, these simulations have only been demonstrated to work for specific applications, either on the global scale (a fire on a simple panel) or on the small scale (a temperature load on a single screw connection), often loaded by a standard fire curve. In this paper, the quality of simulations for combined situations is investigated, i.e. a furnace fire on a set of panels including details and connections. First two existing tests are introduced, a sandwich panel façade test and a studs bolt test, followed by the presentation of their basic fire-structure simulations. In general, the heat transfer analyses agree well with the tests, whereas the structural response analyses need investigation: For the first test, out-of-plane deflections are overestimated at the beginning of the test. A parameter study indicates that this is most likely due to adhesive decomposition, resulting in face delamination and related instabilities. For the second test, the basic simulation does not show any failure, whereas the test failed by vertical bearing. However, with a two-scale model the ultimate load is estimated, and increasing vertical displacements and the onset of vertical bearing are predicted. It is concluded that future tests should include more simulation-relevant measurements. Also, global-scale models need to include features specific to the structure to be simulated, only known after tests and basic simulations, and connections may be decisive for global-scale behaviour, which can be incorporated by a two-scale model. Finally, the tests exhibited complex behaviour across different scales, and modifications and improvements of the simulations increased their fidelity. Therefore fire-structure simulations should always be verified with tests and compared with basic simulations, and modifications in the simulation models should be anticipated. [ABSTRACT FROM AUTHOR]

The post-fire assessment of concrete structures is a complex task that requires the integration of multiple measurements from different techniques. The current approach to integrate information from different sources relies mainly on expert judgement, meaning that no explicit consideration is given to the precision of different techniques. This paper presents a Bayesian updating methodology that integrates information from different sources about the maximum temperature the concrete experienced during fire exposure at a certain depth, such as discoloration and rebound hammer measurements, by considering the uncertainties and errors associated with measurements. The data is then used to update the prior information on the uncertain parameters of interest, here the fire load density and opening factor. These updated distributions provide a better estimate of the fire exposure, thermal and damage gradient and the residual condition of the structure. The proof-of-concept and effectiveness of the proposed methodology are demonstrated through a case study. The results show that the proposed methodology is able to effectively incorporate the uncertainties and errors associated with the assessment techniques, producing more reliable estimates of the fire severity. This method has the potential to improve the post-fire assessment process and provide more accurate information for the rehabilitation of concrete structures. [ABSTRACT FROM AUTHOR]

Fire statistics mirror the outcome of fire prevention. Most fire statistics in Germany deal with the loss of life, value, and fire department actions (number of interventions, nozzles used, or alarm category like a false alarm). However, these results also represent the safety level the legislator has set through the prescriptive building regulations. The current statistics cannot evaluate the level of fire safety and the fulfillment or necessity of fire safety precautions. Today, expert judgment from firefighters is necessary to fill this gap. Here, we show the first evaluation of fire prevention and hazard protection measures by evaluating 900 potentially harming fires throughout Germany. In contrast to minor fires, these fires have advanced to the extent that they could potentially violate the protection objectives outlined in building regulations. The fire department association developed a questionnaire to evaluate the fire safety level and possibly reduce unnecessary fire safety regulations. One hundred twenty-three fire departments carried out the questionnaire, which are responsible for 25% of the German population. Fire prevention officers of the fire departments went to the scene after the fire was extinguished, and the fire safety concept of the building could be evaluated. We found a high rate of injuries, smoke spread, need for rescue by firefighters, and higher than expected firefighter response times after arrival at the scene. Surprisingly, smoke spread rates correlated with building height and not with building age. It was even possible to assess the risk of multiple casualties. Overall, the questionnaire results give insight into the current level of fire safety in existing buildings. Ways and rates for smoke and fire spread prove the importance of second escape routes and the influence of human misconduct. According to these results, current building code regulations are sufficient to prevent fire spread. On the other hand, smoke spreading is a severe threat to people's safety. For example, the data shown can be applied in Bayes nets or other risk calculations to optimize individual building designs or even governmental building codes concerning fire safety engineering. Based on our observations, science, and building codes, authorities could in the future establish a performance-based building code instead of the current prescriptive code. This paper presents the first approach in Germany to quantify the expert judgment of fire departments and use it as a source of knowledge for fire prevention. [ABSTRACT FROM AUTHOR]

Fire testing enables an individual or an organisation to make a claim about how a material, product, or system will perform in operational use. This paper describes and analyses the various reaction-to-fire tests that have used over the last 100 years in the UK. By analysing the commonalities and differences between these tests we propose a 'taxonomy of testing'. We suggest that tests may be classified by the degree to which users may unthinkingly apply the results—without leading to negative fire safety outcomes. We propose three categories: unrepresentative tests; model tests; and technological proof tests. Unrepresentative tests are those which do not mimic building fire scenarios, but have thresholds so conservative that users need not consider whether the test was applicable to their intended application. Model tests are those based on 'models' of expected fire scenarios—users must therefore be confident that the model is sufficiently similar to their application. Technological proof tests are those which provide a more realistic test of a real building system—users must carefully analyse the similarities between their test and the real building before applying the results. From this we conclude that where user competence is low, policymakers should cite only unrepresentative (and conservative tests) within their guidance. Conversely where user competence is high, policy makers may more safety cite model or technological proof tests. The kinds of tests that may be safely cited in guidance are therefore indelibly linked to the expertise of the user. [ABSTRACT FROM AUTHOR]

This paper aims to assess the bond-slip performance of fire exposed high strength concrete (HSC) and SD 550 (super ductile) steel. The SD (super ductile) bars are comparatively more ductile and suited for fire hazards. Bond tests were conducted following RILEM specifications on both HSC and NSC. The samples were fire exposed to steady-state mode following the ISO-834 temperature–time graph. The load-slip response was used to analyze and understand the mechanism of bond NSC and HSC with SD bars exposed to various temperatures. A correlation between the load-slip behavior and the bond-temperature relationship is provided based on test findings. High-strength concrete (HSC), after exposure to 450°C, showed greater bond strength reductions than its normal strength counterpart. The distinctions in the bond response of normal and high-strength concrete (HSC) and characterize the load-slip response on account of exposure to various levels of extreme temperatures have been discussed. Predictive models have been suggested for the degradation of bonds and corresponding slip as well as models to demonstrate the overall response in terms of bond-slip of high-strength concrete exposed to various temperatures. [ABSTRACT FROM AUTHOR]

This paper proposes a fully automated generative network ("SynFAGnet") for automatically creating a realistic-looking synthetic fire image. SynFAGnet is used as a data augmentation technique to create diverse data for training models, thereby solving problems related to real data acquisition and data imbalances. SynFAGnet comprises two main parts: an object-scene placement net (OSPNet) and a local–global context-based generative adversarial network (LGC-GAN). The OSPNet identifies suitable positions and scales for fires corresponding to the background scene. The LGC-GAN enhances the realistic appearance of synthetic fire images created by a given fire object-background scene pair by assembling effects such as halos and reflections in the surrounding area in the background scene. A comparative analysis shows that SynFAGnet achieves better outcomes than previous studies for both the Fréchet inception distance and learned perceptual image patch similarity evaluation metrics (values of 17.232 and 0.077, respectively). In addition, SynFAGnet is verified as a practically applicable data augmentation technique for training datasets, as it improves the detection and instance segmentation performance. [ABSTRACT FROM AUTHOR]