Fire Technology最新文献

Buildings of all types are increasingly becoming complex ‘systems of systems.’ They are subject to evolving societal objectives, new and innovative materials, and in many countries, regulatory ecosystems are having difficulty keeping pace with rapidly changing societal, environmental and technological changes. Two evolving objectives that are stimulating changes to buildings and communities are the desire for a more environmentally sustainable built environment and the need to become more resilient to the many increasingly hazardous impacts of climate change. Unfortunately, in some building designs these objectives are in conflict. As a first step toward a more integrated, holistic tool to aid in the design of sustainable and fire resilient buildings (SAFR-B), this paper develops and applies a first-order decision framework for a midrise apartment building. The SAFR-B framework is built on an analysis of design and regulatory objectives for fire safety and sustainability for buildings, and of risk and decision methods that can support design decisions. It makes use of risk indexing and the analytical hierarchy process (AHP), with initial scoring and weighting of attributes and strategies derived from international experts in the field of fire safety and sustainability through a Delphi process.

Despite the increase in frequency and intensity of wildfires around the world, little research has examined households’ expectations of evacuation logistics and evacuation time estimate (ETE) components during such rapid-onset disasters. To address this gap, this study analyzes data from 152 household responses affected by the devastating 2018 wildfire in Mati, Greece where the second-deadliest wildfire of the 21st century took place. The questionnaire measured residents’ expectations of how they would respond to a future wildfire. This includes the number of vehicles they would take, their evacuation destination and route choices, and their expected evacuation preparation and travel times. Explanatory variables include risk perceptions, wildfire preparedness, wildfire experience, and demographic characteristics. The univariate results reveal some similarities to, but also some differences from, expected evacuation logistics and ETE components in other natural hazards. Moreover, correlation and regression analyses show that expected evacuation logistics and ETE components are primarily related to wildfire preparedness actions. Comparison of this study’s results with other rapid onset events such as tsunamis and hazardous material incidents, as well as longer onset events such as hurricanes, sheds light on household responses to wildfires. Emergency managers can use the similarities in results across studies to better prepare for wildfire evacuations.

The present study is dealing with the heat transfer and deformation of masonry brick walls and an embedded fire safety steel door as well as their mechanical interaction when they were exposed to fire. A numerical approach based on the finite element method was applied to predict the temperatures and deformation. The heat transfer analysis of the wall considered the heat conduction and the radiative heat transfer within the voids of the brick. It was found that the thermal analysis predicted the temperature in the wall with high accuracy. The thermal analysis of the door was limited to the heat conduction and the water vapour transport within the door was neglected. However, the calculated temperatures were found to be reasonable and were further used for the structural analysis. When the door was placed in a central position in the wall, the predicted deformation of the wall was in close accordance to the measured data. The analysis of the door deformation showed that the pressure level and its time-dependency inside the steel door is a crucial factor for the simulation’s accuracy. When the door was placed in an asymmetric position, the wall deformation was increasing significantly. This phenomenon was also covered by the simulation, when the stiffness of the wall boundary condition was decreased. Although the numerical model was capable to calculate the deformation during the fire exposure, further research on the pressure inside the door and the mechanical conditions of the wall at the boundaries has to be done.

Fire is one of the major disasters that threaten the safety of industrial and mining enterprises. In response to the limitations of existing flame and smoke detection algorithms, which fail to meet the practical application requirements of high detection rates, low false alarm rates, and strong real-time performance, this paper proposes an industrial and mining fire detection algorithm based on the improved YOLO. First, the CFM_N module is built to more effectively capture both local and global data in the feature map. Then, the improved spatial pyramid pooling module SPPFCSPC is proposed to better extract and fuse multi-scale target features. Finally, the improved downsampling module is put forward to optimize the multi-scale fusion module and to reduce the computational complexity. Comparison experiments on self-made datasets show that the proposed algorithm obtains 91.7% mAP and 87.7% F1, which are superior to the results of YOLOv5-YOLOv8 algorithms. And this algorithm achieves accurate detection of small target flames and smoke, as well as medium and large flame and smoke targets in close and medium distances. So it can meet the real-time detection task of fire in large-scale complex industrial and mining scenes.

This study investigates the behavior of super ductile (SD) reinforcing steel bars after exposure to elevated temperatures, highlighting their distinctions and superior performance compared to conventional steel types such as cold-worked, hot-rolled, and thermo-mechanically treated (TMT) bars. The research examines the changes in mechanical properties, including yield strength, ultimate strength, modulus of elasticity, and ductility, through detailed stress–strain analysis and mechanical property evaluation across varying temperature ranges. The findings demonstrate that SD bars exhibit enhanced mechanical properties under high-temperature conditions, retaining higher yield and ultimate strengths, and maintaining a more pronounced strain hardening region compared to other steel types. Specifically, SD bars preserve higher residual strength after exposure to 800°C, significantly outperforming cold-worked and hot-rolled bars. The modulus of elasticity of SD bars shows better stability at moderate temperatures and a less pronounced decrease at higher temperatures, reflecting their superior ability to absorb energy before failure. Parabolic regression models were developed to predict the degradation in yield and ultimate strengths, while polynomial curve fitting methods were used to establish stress–strain models for post-heating scenarios. This research fills a critical gap in the current understanding and provides robust degradation models that are essential for the design and safety assessment of reinforced concrete structures using SD550 steel under thermal stress conditions.

Pressure-sensitive adhesive tapes are used in automotives, railway vehicles and construction, where flame retardancy is of major importance. This is why industrial applicants often buy, and industrial tape manufacturers often produce, flame-retardant adhesive tapes, advertised for their good flammability characteristics. Yet, how flame-retardant tapes influence the fire behavior of bonded materials is a rather open question. To investigate this issue, three different substrates were bonded, using eight double-sided adhesive tapes containing two different carriers and two different flame retardants. The bonded substrates were compared to their monolithic counterparts in terms of flammability, fire behavior and fire stability. The fire behavior of adhesive tape bonded materials differed significantly from the monolithic substrates. The usage of different adhesive tapes let to different burning behavior of the bonded materials mainly due to different carrier systems. In contrast, the implementation of flame retardant into the adhesive had rather minor or no effect on the burning behavior of the bonded substrates despite their positive effect on the flammability of the free-standing tape. The carrier changed the HRR curve in the cone calorimeter and was able to both, reduce and increase fire hazards. Using the carrier with the better fire performance can lower the fire growth rate by 20%, the peak of heat release rate by 27%, and the maximum average rate of heat emission by 30% in cone calorimeter tests. Overall, the fire behavior of bonded materials is a complex interaction between substrate, adhesive, and carrier, and depends on the fire scenario the materials are exposed to.

The existing early-warning methods primarily rely on detecting structural displacements which are often challenging to measure accurately in real fire scenarios. To develop innovative early-warning strategies, this paper experimentally and numerically investigates the fire-induced collapse of an 8 m × 6 m steel portal frame assembly. Detailed thermo-structural responses of the frame were measured and presented, including the displacements and rotations. The results revealed that the vertical mid-span displacement and horizontal displacement at the rafter end are key to developing an effective early-warning system. Structural rotations seem sensitive to structural deformation and emerges as a valuable safety indicator for structural systems. Furthermore, parametric analyses were carried out in order to investigate the effect of load ratio, fire protection and heating curve on key parameters of the structure subjected to fires. It is discovered that the increased load ratio can reduce the peak value of vertical displacement at the mid-span of the rafter. A rotational angle of 6° in the steel beams is optimal for predicting the collapse of steel portal frames in fire conditions. Based on the parametric studies, an innovative early-warning approach using rotational angles is proposed and validated against the test frame, demonstrating significant applicability and reliability. The rotation-based early-warning approach works in two distinct stages, being activated respectively by the maximum and zero rotational angles at the end of rafter. The early-time ratios for the respective warning stages are 0.65 and 0.88. For better precision and practical reliability, it is further recommended to combine the rotation-based and displacement-based approaches for the on-site early-warning of fire-induced collapse of portal frames.

Smoke stratification in a V-shaped tunnel fire is complex due to the coupling effects of the double stack effect induced by the inclined tunnel structure, the fire thermal buoyancy, and the drag force caused by water spray system. This work investigates the influence of water spray flow rate (0 L/min to 600 L/min), atomization angle (0° to 150°) and distance between fire source and grade change point (0 m to 120 m) on smoke stratification in a symmetrical V-shaped tunnel through numerical simulations. The results show that the increase of water spray flow rate causes the increasing drag force which destabilizes smoke layer and contributes to the reduction of smoke layer thickness. While the water spray angle has little effect on smoke layer thickness. Through the dimensionless analysis and simulation results, a correlation for smoke layer thickness considering water spray parameters is proposed. Water spray effects on Fr describing the smoke stratification correspond to these on smoke layer thickness. That is, Fr decreases with the increase of water spray flow rate and is weak dependent on the water spray angle, and the critical Fr for turning point of the dominant effect of thermal buoyancy and drag force is linearly related to fire heat release rate. As the distance between fire source and grade change point increases, Fr changes a little on first double-slope control stage, increases on the left and decreases on the right of fire source, and eventually both levels off on second transition phase stage, thus tends to be stable on third single slope control stage.