Search Results (292)

An investigation employing multiple diagnostic techniques was conducted to evaluate the post-fire condition and residual structural safety of a fire-damaged precast concrete industrial building. The evaluation included a detailed visual inspection, mechanical testing of extracted concrete cores, and mineralogical and microstructural analysis through thermo-chemical methods, namely X-ray Diffraction, Scanning Electron Microscopy, and Energy-Dispersive X-ray Spectroscopy, alongside tensile strength tests of reinforcement bars sampled from the affected structure. The building was divided into five sections according to the severity and extent of observed fire damage. Results indicated that the highest in situ temperatures were attained in the most heavily damaged section, whereas the remaining sections experienced progressively lower temperatures, remained below approximately 600 °C. Despite the severe fire exposure in localized areas, all assessed structural elements maintained adequate residual integrity. The reinforcing steel exhibited satisfactory residual mechanical properties, exhibiting yield strengths ranging from 550 to 600 MPa. The integration of visual, mechanical, and microstructural assessments provides a reliable framework for estimating fire temperatures and supporting structural rehabilitation decisions. Full article

In this study, the comparative residual performance of fire-exposed reinforced concrete (RC) beams with rectangular and T-shaped cross-sections is investigated. Two concrete beams, one with a T-section and the other with a rectangular section, were tested under the combined effects of fire exposure and structural loading. Data generated in the tests during and following fire exposure is utilized to compare the thermal and structural response of the beams. The results indicate a notable difference in the temperature evolution, mid-span deflection, and the residual capacity of the beams. The T-beam experienced greater deflection and stiffness degradation due to its larger exposed surface area (approximately 17% higher than the rectangular beam) and flange geometry, despite comparable peak rebar temperatures. A simplified approach, based on the maximum concrete and rebar temperatures and corresponding strength reductions, is proposed to evaluate the residual capacity of fire-exposed RC beams. For equal cover depth to reinforcement, peak rebar temperature is unaffected by cross-section shape as long as the web of the T-beam is not slender. T-shaped beams with similar overall depth exhibit greater post-fire strength retention than rectangular beams when the neutral axis lies within the flange. A 20% reduction in the web thickness and a combined reduction of 20% in web and 37% in flange thickness result in a comparable decrease in the flexural capacity to that of the rectangular beams of similar depth, indicating that the flange plays a key role in maintaining post-fire performance. Full article

This study presents an experimental investigation into the rehabilitation of fire-damaged reinforced concrete (RC) columns using Ultra-High-Performance Concrete (UHPC) under an eccentric load of (e = 45 mm). The experimental program comprised nine small-scale RC column specimens, which were divided into two groups based on exposure temperatures of 500 °C and 700 °C, applied using a specially designed furnace. A control column that was not exposed to fire was also tested for comparison. The study included two fire exposure durations: 60 and 120 min. During the heating phase, the columns were subjected to a pre-applied axial load equal to 50% of their ultimate capacity (Pu). After sustaining fire-induced damage, the columns were rehabilitated using UHPC jacketing. The experimental results revealed a reduction in the ultimate load-carrying capacity of the RC columns with increasing fire temperature and exposure duration. Specifically, the load capacity decreased by 22.68% and 33.89% when exposed to 500 °C for 60 and 120 min, respectively, and by 42.02% and 49.02% when exposed to 700 °C for 60 and 120 min, respectively, compared with the control column. However, strengthening the fire-damaged columns with UHPC significantly enhanced their structural performance, resulting in an increase in ultimate load capacity ranging from 81.88% to 157.14% compared with their corresponding fire-damaged unstrengthened specimens. Based on the experimental findings, the load lateral displacement response at mid-height, load–axial deformation curves, failure modes, ductility, and stiffness characteristics of the columns were analysed. The study concludes that the use of UHPC in rehabilitating fire-exposed columns substantially improves most of these structural properties. Full article

Recycled cellulosic fiber (RCF) composites offer significant potential to reduce environmental burdens associated with virgin fiber production; however, their broader adoption remains limited by feedstock variability, recycling-induced degradation, and uncertainty regarding long-term performance. This review critically synthesizes recent advances in RCF composites using a structure–processing–performance–sustainability framework, treating recycled fibers as secondary materials with distinct morphological, chemical, and mechanical characteristics rather than direct substitutes for virgin reinforcements. Emphasis is placed on the effects of fiber shortening, surface damage, moisture sensitivity, and altered surface chemistry on interfacial adhesion, load transfer efficiency, durability, and failure mechanisms. The analysis reveals that many reported performance discrepancies arise from poorly defined structure–property relationships and the absence of standardized characterization, grading, and durability testing protocols for recycled fibers. Addressing these gaps enables more reliable predictive modeling and application-specific material design. Beyond mechanical behavior, the review evaluates various critical factors for integration into higher-value applications such as durability under realistic service conditions, including environmental aging, fire performance, and long-term stability. Emerging strategies such as hybrid reinforcement, environmentally benign surface functionalization, smart functionalities, and recyclable or bio-based matrices are assessed for their potential to enhance multifunctionality and circularity. Overall, the findings indicate that RCF composites can meaningfully contribute to circular material systems if materials design, performance validation, and life-cycle assessment are integrated systematically. Advancing standardized evaluation and aligning materials innovation with circular economy principles are essential to transition RCF composites from downcycled applications to reliable, performance-oriented components in sustainable engineering systems. Full article

Frequent forest fires cause serious damage to ecosystems and socioeconomic systems, increasing the importance of fire prevention and risk assessment. Forest fuel is a fundamental determinant of forest fire behavior and a key component of fire risk management. However, a systematic synthesis of its global research evolution and emerging scientific challenges remains relatively insufficient. On the basis of 1257 publications retrieved from the Web of Science Core Collection (2010–2025) with the themes of “wildfire fuel” and “forest fuel,” this study employed CiteSpace for bibliometric analysis to systematically investigate research trends, collaboration patterns, and thematic evolution. The results show that forest fuel research has exhibited sustained growth overall, with notable peaks in 2016 and 2020, and reaching a historical high in 2023. The United States dominated both in publication output and institutional collaboration networks, forming a core research cluster together with Australia and Canada. Keyword co-occurrence and burst analyses revealed a shift in research hotspots—from early focus on forest fuel models and risk assessment at the wild–urban interface (WUI)—toward concerns about climate-change-driven fire seasonality, fuel moisture dynamics, and emergency response issues, reflecting the growing influence of climate change on wildfire patterns. Notably, this study identified several critical research gaps, including limitations in cross-regional integration of fuel moisture studies, insufficient attention to ignition prevention in WUI residential settings, and a lack of reproducible, open bibliometric workflows. By systematically mapping the knowledge structure and evolutionary trajectory of forest fuel research, this study provides a globally informed knowledge framework for the future advancement of forest fuel science and its deeper integration with forest fire management and policy making. Full article

Bridges are critical components of transportation networks, and fire accidents can significantly impair their structural integrity, leading to safety risks and major economic losses. This study presents a comprehensive inspection, materials testing, repair, and field load testing program for a full-scale concrete box girder bridge (Delta Bridge, Alexandria, Egypt) following a fire exposure on two spans. A total of 28 concrete core samples were extracted and tested, revealing average compressive strengths of 48.50 MPa (slab), 53.90 MPa (web), and 45.88 MPa (columns), representing moderate reductions of approximately 8.5%, 7.9%, and 10.8%, respectively, relative to the original in situ concrete strength recorded during construction, and 29.2%, 43.7%, and 30.0% increases over the minimum acceptance limits specified by Egyptian code of practice (ECP 203). Tensile strength tests on reinforcement bars indicated an average yield strength reduction coefficient of 0.87, corresponding to an estimated peak exposure temperature of 600 °C, yet still satisfying Egyptian code requirements (≥500 MPa). Field static load tests using 40-ton tri-axle trucks demonstrated maximum midspan deflections of 6.7 mm in fire-exposed spans and full recovery (>94%) upon unloading, confirming that the residual stiffness and load-carrying capacity were within acceptable limits. Based on these results, a targeted repair program was executed, including concrete cover replacement with shotcrete; steel derusting; surface coating; and bearing replacement, followed by a verification load test that confirmed the effectiveness of the rehabilitation. This case study demonstrates a robust framework for post-fire condition assessment, residual capacity evaluation, and repair validation of concrete box girder bridges. The methodology and findings provide valuable guidance for engineers and transportation authorities in mitigating fire-induced risks and ensuring the safe reopening of critical bridge infrastructure. Full article

Automatic sprinkler systems are widely used for fire protection in various buildings, with deluge valves serving as the core component of these systems. Traditional deluge valves employ a diaphragm-type design (Zoning Sprinkler Fire Monitor, ZSFM), which is prone to significant safety hazards such as corrosion and damage due to uneven pressure distribution on the diaphragm. This study modified a 150 mm diameter ZSFM to a non-pressure diaphragm type, establishing and validating a CFD model of the internal flow field. Based on the original structure, six drag reduction optimization cases are designed. Among these, case 5 exhibits the minimum inlet-to-outlet pressure drop of 0.050 MPa under rated operating conditions, meeting and significantly exceeding the fire protection industry standard (≤0.08 MPa). Full article

Fire safety in heritage buildings is a major challenge. It is necessary to find effective solutions that minimise damage to the protected building and do not cause damage or diminish the aesthetic value of the building. This requires not only special equipment, but often also specific solutions. The easiest way to increase the fire safety level of a building is to retrofit it with active fire protection systems. The aim of this paper is to review fire detection solutions suitable for historic buildings, with particular emphasis on minimally invasive and visually unobtrusive systems. The study combines a structured review of point, linear, and aspirating smoke detection technologies with a demonstrative parametric sizing assessment of an aspirating smoke detection (ASD) system using a manufacturer-supported sizing software. The sizing analysis investigates how changes in sampling hole diameter and fan settings influence transport time, sensitivity distribution, and system balance under constrained routing conditions typical of heritage interiors. The results highlight key trade-offs between response time and system balance, providing practical guidance for designers and conservation professionals. The findings support the development of fire detection strategies that align with European recommendations for heritage protection while ensuring technical effectiveness. The paper also provides a guideline to professionals, architects, restorers, and heritage experts, who have key roles in the protection of heritage structures. Full article

The extensive integration of lithium-ion batteries (LIBs) into modern technologies—including portable electronics, electric vehicles (EVs), and battery energy storage systems (BESSs)—has created a critical dependency on the supply of raw materials. The ongoing shift toward clean mobility is expected to further intensify this demand. This trend coincides with a projected increase in battery waste: over the next decade, millions of tons of EV and BESS batteries will reach their end-of-life (EOL), alongside the generation of considerable manufacturing scrap. Recycling is essential for recovering critical materials and reducing dependency on primary mining, thereby benefiting the circular economy and environmental sustainability. However, EOL-LIBs are more prone to thermal runaway due to defects and aging-induced degradation, which can lead to fire and explosion incidents, as well as associated environmental and health hazards. Such incidents have been increasingly reported in recent years during transportation, storage, handling, and illegal disposal, resulting in potential loss of life, property damage, and ecological degradation. To ensure the safe design and operation of the battery recycling industry, this work provides an updated overview of the health, safety and environment (HSE) hazards posed by EOL-LIBs and the safety measures required to mitigate these hazards. First, this work outlines the structures, components, and aging mechanisms of LIBs. Second, it summarizes the state-of-the-art recycling pathways and relevant process risks, such as deactivation, dismantling, and mechanical and thermal pretreatments. Third, it reviews recent safety incidents initiated by thermal runaway of EOL-LIBs and recycling intermediates like black mass, with an emphasis on storage and handling. Fourth, recommendations for future work regarding the safe storage and processing of EOL batteries are provided. Finally, conclusions and perspectives on future research directions are presented. Continued research and development in this field are essential to improve recycling methods, optimize processes, and ensure the safe and sustainable management and legislation of EOL lithium-ion batteries. Full article

Electric vehicles (EVs) are widely recognized as a key strategy for improving global sustainability; however, their implications for building safety, particularly under fire conditions, require further investigation. This study examines the structural response of reinforced concrete (RC) beams exposed to EV fire scenarios, which are characterized by more severe thermal demands than the ISO 834 standard fire curve adopted in structural fire design, including EN 1992-1-2. A coupled thermal–mechanical finite element analysis (FEA) was performed on nine RC beams, considering variations in reinforcement layout, rebar diameter, and concrete cover thickness. When compared with fire resistance times predicted by standardized design procedures, the numerical results indicate that EV fires accelerate building damage by up to 27% within the first 60 min of exposure. Increasing the concrete cover to at least 30 mm and adopting multiple reinforcement layers were shown to enhance fire performance by reducing heat transfer to the steel reinforcement and lowering stress levels within the cross section. The findings demonstrate that current fire design provisions may underestimate the structural demands imposed by EV fire scenarios. Consequently, this study highlights the need to revise fire resistance criteria and reinforcement detailing rules to ensure adequate safety and resilience of RC structures in sustainable built environments subjected to emerging EV fire hazards. Full article

Emergency and Disaster Assembly Areas (EDAA) are designated safe zones where basic needs can be met until temporary shelters are established following natural or man-made disasters like floods, fires, earthquakes, explosions, or chemical incidents. Promptly relocating disaster victims to these areas is crucial for minimizing loss of life and facilitating effective search and rescue operations by maintaining an uninterrupted flow of information. To prepare for disasters like earthquakes, which cause significant material and emotional damage to large populations, sustainable disaster management must be ensured to evaluate site suitability, correct deficiencies, and avoid inappropriate locations. This study will examine the evaluation criteria for EDAAs established by the Tunceli Provincial Disaster and Emergency Management Authority (AFAD) in terms of area, structure, security, and accessibility, taking into account the region’s specific characteristics. Based on a literature review, eleven criteria have been proposed and ranked using the Besson mean ranking method. Areas have been classified into four categories (e.g., adequate, not suitable) using the optimistic, pessimistic, and comprise approaches of the Assignment Rule Driven by Attitudes (ARDA) and the ORESTE-Sort method. The examination of 19 EDAA provides two perspectives: an optimistic view that recommends classifying eleven areas as first class and using all areas as they are, and a pessimistic view that calls for urgent improvements in three areas and states that one area (EDAA 1) is deemed unsuitable due to its assignment to class ${\mathrm{K}}_4$. It is also advised that the second area should not be used, despite being rated as class ${\mathrm{K}}_3$, due to its proximity to the river and its slope characteristics. The study also performs a sensitivity analysis of the method and provides recommendations for future research. Full article

Fire hazard events for road tunnel has correspondingly increased with battery electric vehicle (BEV) penetration rate rising. Compared with conventional internal combustion engine vehicles (ICEV), the research on damage degree of road tunnels caused by BEV fires is not mature. To this end, the temperature distribution and residual load-bearing capacity of road tunnel were studied considering the difference temperature rise curve of BEV fire and ICEV fire. By using the indirect thermal–mechanical coupling approach, the temperature field obtained from fire simulations was applied to the structural model. The assessment of mechanical properties after high-temperature exposure was conducted using the deflection limit method and concrete plastic damage theory. The results show that different heating curve conditions have significant differences in the temperature field and damage distribution of the tunnel. Although different fire effects cause different degrees of structural damage to the tunnel lining, the overall bearing capacity of the structure still has a certain surplus. The results provide a basis for the formulation of repair schemes and reinforcement measures for tunnel structures to assess the safety and normal operation of tunnel structures. Full article

Fire accidents in road tunnels can cause a significant number of fatalities and severe damage to tunnel structures. The tunnel European directive applies to the trans-European road network and requires the use of active smoke control systems in most tunnels longer than 1000 m. Research has investigated whether shorter tunnels without active smoke control systems are safe. If smoke contaminates the lower layer where people evacuate, it can impair visibility. This disturbs egress and may cause intoxication and, eventually, death. The FireFoam computer code was applied to the Memorial Tunnel fire ventilation tests for validation. This work investigates the effect of varying the heat release rate (HRR), ranging from 6 to 100 MW, under a wind velocity of 0.77 m/s and in the absence of wind. Results show that high HRR moves the start of lower layer smoke contamination closer to the fire source, reducing the distance from 390 m at 14 MW to as close as 210 m at 100 MW. An analytical model was developed to predict the distance from the fire source where smoke can contaminate the lower layer and was subsequently improved to account for HRR variation. Full article

Early detection of small-scale fires is crucial for minimizing damage and enabling rapid emergency response. While recent deep learning-based fire detection systems have achieved high accuracy, they still face three key challenges: (1) limited deployability in resource-constrained edge environments due to high computational costs, (2) performance degradation caused by feature interference when jointly learning flame and smoke features in a single backbone, and (3) low sensitivity to small flames and thin smoke in the initial stages. To address these issues, we propose a lightweight dual-stream fire detection architecture based on YOLOv5n, which learns flame and smoke features separately to improve both accuracy and efficiency under strict edge constraints. The proposed method integrates two specialized attention modules: ESCFM++, which enhances spatial and channel discrimination for sharp boundaries and local flame structures (flame), and ESCFM-RS, which captures low-contrast, diffuse smoke patterns through depthwise convolutions and residual scaling (smoke). On the D-Fire dataset, the flame detector achieved 74.5% mAP@50 with only 1.89 M parameters, while the smoke detector achieved 89.2% mAP@50. When deployed on an NVIDIA Jetson Xavier NX (NVIDIA Corporation, Santa Clara, CA, USA)., the system achieved 59.7 FPS (single-stream) and 28.3 FPS (dual-tream) with GPU utilization below 90% and power consumption under 17 W. Under identical on-device conditions, it outperforms YOLOv9t and YOLOv12n by 36–62% in FPS and 0.7–2.0% in detection accuracy. We further validate deployment via outdoor day/night long-range live-stream tests on Jetson using our flame detector, showing reliable capture of small, distant flames that appear as tiny cues on the screen, particularly in challenging daytime scenes. These results demonstrate overall that modality-specific stream specialization and ESCFM attention reduce feature interference while improving detection accuracy and computational efficiency for real-time edge-device fire monitoring. Full article

This study developed a fire evacuation simulation model for a six-level underground station to evaluate evacuation efficiency under both dynamic and static conditions, including structural damage, smoke propagation, and real-time crowd congestion. Two representative pathfinding algorithms, Dijkstra’s and A*, were applied to analyze evacuation performance across eight fire scenarios occurring at different locations within the station. When only static factors were considered, both algorithms yielded identical maximum evacuation times, indicating comparable performance. However, the A* algorithm exhibited a significantly shorter computation time than Dijkstra’s, demonstrating higher operational efficiency. When dynamic variables such as real-time congestion and smoke-induced visibility reduction were introduced, the maximum evacuation times varied irregularly between the two algorithms. This outcome suggests that, under dynamic fire conditions, route guidance based solely on current information rather than predictive modeling may lead to suboptimal evacuation outcomes. Therefore, this study emphasizes the importance of establishing a predictive disaster management system capable of forecasting fire and smoke propagation, as well as a centralized control system that can dynamically distribute evacuees to enhance evacuation efficiency in deep underground stations. Full article