Search Results (73)

This study investigates the robustness of steel moment-resisting frames (MRFs) under column loss scenarios, both in undamaged and post-seismic conditions. In this context, robustness is defined as the ability of a damaged structure to prevent progressive collapse following an earthquake. A parametric investigation was conducted on 48 three-dimensional MRF configurations, varying key design and geometric parameters such as the number of storeys, span length, and design load combinations. Nonlinear dynamic analyses were performed using realistic ground motions and column loss scenarios defined by UFC guidelines. The effects of pre-existing seismic damage, façade claddings, and joint typologies were explicitly accounted for using validated component-based modelling approaches. The results indicate that long-span, low-rise frames are more vulnerable to collapse initiation due to higher plastic demands, while higher-rise frames benefit from load redistribution through their increased redundancy. In detail, long-span, low-rise frames experience roughly ten times higher displacement demands than their short-span counterparts, and post-seismic damage has limited influence, yielding rotational demands within 5–10% of the undamaged case. The Reserve Displacement Ductility (RDR) ranges from approximately 6.3 for low-rise, long-span frames to 21.5 for high-rise frames, highlighting the significant role of geometry in post-seismic robustness. The post-seismic damage was found to have a limited influence on the dynamic displacement and rotational demands, suggesting that the robustness of steel MRFs after a moderate earthquake is largely comparable to that of the initially undamaged structure. These findings support the development of more accurate design and retrofit provisions for seismic and multi-hazard scenarios. Full article

Post-earthquake fires (PEFs) represent a complex, cascading hazard in which seismic damage creates ignition conditions that can overwhelm urban infrastructure and severely compromise structural integrity. Despite growing scholarly attention, the literature on PEFs remains fragmented across disciplines, lacking a consolidated understanding of structural vulnerabilities, urban-scale impacts, and response strategies. This study presents a systematic and thematic synthesis of 54 peer-reviewed articles, identified through a PRISMA-guided screening of 151 publications from the Web of Science Core Collection. By combining bibliometric mapping with thematic clustering, the review categorizes research into key methodological domains, including finite element modeling, experimental testing, probabilistic risk analysis, multi-hazard frameworks, urban simulation, and policy approaches. The findings reveal a dominant focus on structural fire resistance, particularly of seismically damaged concrete and steel systems, while highlighting emerging trends in sensor-based fire detection, AI integration, and urban resilience planning. However, critical research gaps persist in multi-hazard modeling, firefighting under partial collapse, behavioral responses, and the integration of spatial, infrastructural, and institutional factors. This study proposes an interdisciplinary research agenda that connects engineering, urban design, and disaster governance to inform adaptive, smart-city-based strategies for mitigating fire risks in seismic zones. This work contributes a comprehensive roadmap for advancing post-earthquake fire resilience in the built environment. Full article

Springs located in urban historic areas are important for groundwater management, the protection of green spaces, and the preservation of park functions and urban structure. This article presents the results of a study of selected Warsaw springs in the city center under conservation protection, focusing on their hydrogeological characteristics, hydrogeochemical analysis, and pressures associated with urban development. Field and laboratory analyses, as well as hydrodynamic modeling, made it possible to assess the quantity and quality of water from the springs. Hydrodynamic studies showed that the area of the spring recharge zone of 13.77 ha is characterized by an average time of water exchange of approx. 26 years and a low infiltration recharge, an average of 18 mm/year. Hydrogeochemical analyses showed that spring water has a complex, multi-ion hydrogeochemical type: Cl-SO₄-HCO₃-Ca-Na, Cl-HCO₃-SO₄-Ca-Na, Cl-HCO₃-Na-Ca, and NO₃-Cl-HCO₃-Ca-Na, including the occurrence of hazardous substances such as PAH and BTEX, PCBs, non-ionic detergents, and heavy metals. The results indicate that urbanization significantly affects groundwater levels and spring recharge areas, which can limit the availability of water in green and recreational areas. The results of the study indicate the need for action to increase groundwater resources through managed aquifer recharge for rainwater management in densely built-up areas. In terms of water quality measures, due to the unsatisfactory chemical water status, the use of spring water for irrigation of urban vegetation or its incorporation into the active recreational infrastructure of the park currently appears to be fraught with considerable risk, hence the need to take protective action in the spring recharge zone through the regular monitoring of groundwater quality, the legal designation of protection zones, and the implementation of policies that support urban water retention. It is necessary to implement pre-treatment solutions (aeration, desalination) or introduce appropriately resistant vegetation. Any type of activity that allows the use of water after treatment will certainly contribute to making the park more attractive as a place of recreation and leisure for residents. Findings from the research can support decisions on protecting green spaces and adapting cities to climate change. Full article

In smart meters, loose contact at screw terminals can lead to prolonged overheating and arcing, posing significant fire hazards. To mitigate these risks through early fault detection, this study proposes a data-driven framework integrating the Local Outlier Factor (LOF) and Multiple Linear Regression (MLR) algorithms. Voltage differentials, extracted from operational data collected via a simulated multi-meter metering enclosure, are leveraged to diagnose terminal contact degradation. Specifically, LOF identifies arc faults, characterized by abrupt and transient voltage deviations, by detecting outliers in voltage differentials, while MLR quantifies contact resistance through regression analysis, enabling precise loose contact detection, a condition associated with gradual and persistent voltage changes due to increased resistance. Extensive validation demonstrates the framework’s robustness, outperforming conventional centralized methods in diagnostic accuracy and adaptability to diverse load conditions. Full article

Reinforced concrete flat slab–column structures, lacking the redundancy provided by a beam–column system, are susceptible to punching shear failure under extreme loading conditions, which may lead to progressive collapse with catastrophic consequences. A systematic review of recent advancements in the progressive collapse resistance of flat slab–column systems has been provided, categorizing the methodologies into experimental investigation, theoretical analysis, and numerical simulation. Experimental studies primarily utilize the Alternative Load Path methodology, incorporating both quasi-static and dynamic loading protocols to assess structural performance. Different column removal scenarios (e.g., corner, edge, and interior column failures) clarify the load redistribution patterns and the evolution of resistance mechanisms. Theoretical frameworks focus on tensile and compressive membrane actions, punching shear mechanism, and post-punching shear mechanism. Analytical models, incorporating strain-hardening effects and deformation compatibility constraints, show improved correlation with experimental results. Numerical simulations use multi-scale modeling strategies, integrating micro-level joint models with macro-level structural assemblies. Advanced finite element analysis techniques effectively replicate collapse behaviors under various column failure scenarios, validated by full-scale test data. This synthesis identifies key research priorities and technical challenges in collapse-resistant design, establishing theoretical foundations for future investigations of flat slab systems under multi-hazard coupling effects. Full article

Well leakage is a recurring hazard in drilling operations that can lead to significant loss of drilling fluids and serious consequences when drilling fluids seep into the formation. Increasing drilling depths correspond to elevated formation temperatures and pressures, which place stringent demands on leakage control materials. In this study, a high-pressure- and high-temperature-resistant branched resin, poly-BDEB, was synthesized using 2,2-bis(4-hydroxyphenyl)propane diepoxyglycidyl ether and epoxy crack adhesive B. The properties of the branched resin poly-BDEB were characterized. Leakage control performance of the branched resin poly-BDEB was evaluated through single-stage and multi-stage crack plugging experiments to determine its effectiveness. The results show that poly-BDEB maintains structural stability under pressures of up to 198.33 MPa. Poly-BDEB has a stable structure and will not be thermally decomposed at 352.25 °C. These properties demonstrate poly-BDEB’s excellent pressure and temperature resistance. The density of branched resin poly-BDEB is 1.07 g/cm³. When its concentration in the drilling fluid reaches 24% (8%A + 8%B + 8%C), it still maintains good sedimentation stability. Poly-BDEB can effectively plug single-stage and multi-stage fractures ranging from 1 to 3 mm in width. Unlike conventional leakage circulation materials (LCMs), poly-BDEB features a branched molecular structure that improves its mechanical strength, thermal stability, and bridging efficiency in fractures. This study can provide technical support for leakage control in deep and ultra-deep wells during drilling. Full article

This study proposes a novel drone-based semi-airborne total-field magnetometric resistivity (SA-TFMMR) system for high-resolution detection of conductive fracture zones in geologically hazardous terrains. The system integrates a high-power, low-frequency grounded-wire transmitter with a drone-mounted total-field magnetometer, achieving high survey efficiency and extensive data coverage in mountainous areas. We develop a 3D inversion framework incorporating terrain-adaptive depth weighting, which successfully images a dipping water-saturated fracture zone model beneath a reservoir overburden at a tunnel water gushing accident site. Sensitivity analyses of SA-TFMMR reveal that the effectiveness of detection is controlled by the source-target coupling and the orientation of the target body with respect to the geomagnetic field. Optimal current injection along target strike directions amplifies magnetic anomalies, and orthogonal multi-source configurations can enhance imaging resolution. This UAV-geophysical integration provides a paradigm for pre-disaster monitoring of water-related geohazards. Full article

Nitrophenols are persistent organic pollutants that pose serious environmental and health risks due to their toxic and lipophilic nature. Their persistence arises from strong aromatic stability and resistance to biodegradation, while their lipophilicity facilitates bioaccumulation, exacerbating ecological and human health concerns. To address this challenge, this study focuses on the synthesis and characterization of two different types of hybrid multi-core magnetic catalysts: (i) cobalt ferrite (Co-Fe₂O₄), which exhibits ferrimagnetic properties, and (ii) magnetite (Fe₃O₄), which demonstrates close superparamagnetic behavior and is coated with a novel and less hazardous phloroglucinol–glyoxal-derived resin. This approach aims to enhance catalytic efficiency while reducing the environmental impact, offering a sustainable solution for the degradation of nitrophenols in aqueous matrices. Transmission electron microscopy (TEM) images revealed the formation of a multi-core shell structure, with carbon layer sizes of 6.6 ± 0.7 nm for cobalt ferrite and 4.2 ± 0.2 nm for magnetite. The catalysts were designed to enhance the stability and performance in catalytic wet peroxide oxidation (CWPO) processes using sol–gel and solution combustion synthesis methods, respectively. In experiments of single-component degradation, the carbon-coated cobalt ferrite (CoFe@C) catalyst achieved 90% removal of 2-nitrophenol (2-NP) and 96% of 4-nitrophenol (4-NP), while carbon-coated magnetite (Fe₃O₄@C) demonstrated similar efficiency, with 86% removal of 2-NP and 94% of 4-NP. In the multi-component system, CoFe@C exhibited the highest catalytic activity, reaching 96% removal of 2-NP, 99% of 4-NP, and 91% decomposition of H₂O₂. No leaching of iron was detected in the coated catalysts, whereas the uncoated materials exhibited similar and significant leaching (CoFe: 5.66 mg/L, Fe₃O₄: 12 mg/L) in the single- and multi-component system. This study underscores the potential of hybrid magnetic catalysts for sustainable environmental remediation, demonstrating a dual-function mechanism that enhances catalytic activity and structural stability. Full article

Sound wave fire suppression, an emerging firefighting technology, demonstrates unique potential by regulating the physicochemical processes of flames. This paper systematically reviews the research progress in acoustic fire extinguishing technology. Through a literature review and systematic comparison of existing methodologies, it reveals the core mechanisms of flame suppression: low-frequency sound waves (40–80 Hz) disrupt combustion stability via airflow disturbance, while high-frequency waves (>1 kHz) may rely on thermal effects or resonance mechanisms, with sound pressure and waveform significantly affecting extinguishing efficiency. Experimental results demonstrate that acoustic cavity focusing technology extends the effective fire suppression distance to 1.8 m while improving cooling efficiency by 10–20%. Integration with drone platforms and adaptive feedback systems enhances fire extinguishing energy efficiency by over 30%. When combined with water mist, this approach reduces suppression time to 30 s while mitigating sound pressure hazards. However, the critical parameters distinguishing sound-induced “flame enhancement” from “suppression” remain undefined, with insufficient research on adaptability to solid fuels and complex environments (microgravity, confined spaces), and a lack of high-temperature-resistant acoustic materials and multi-physics coupling models. Current fire suppression technologies predominantly rely on airflow disturbance-driven indirect mechanisms, whose stability remains questionable under extreme scenarios. Future advancements require breakthroughs in acoustic metamaterials, the integration of intelligent algorithms, and the collaborative optimization of multi-technology systems to facilitate the transition of acoustic wave-based fire suppression from laboratory settings to real-world industrial firefighting applications. Additionally, this study proposes an optimized solution that integrates acoustic waves with complementary fire suppression approaches, aiming to enhance overall firefighting effectiveness. Concurrently, an interdisciplinary research framework must be established to address the dual challenges of mechanistic elucidation and practical implementation. Full article

This paper presents a comprehensive on-site decision-making framework for assessing the structural integrity of a jacket-type offshore platform in the Gulf of Mexico, installed at a water depth of 50 m. Six critical analyses—(i) static operation and storm, (ii) dynamic storm, (iii) strength-level seismic, (iv) seismic ductility (pushover), (v) maximum wave resistance (pushover), and (vi) spectral fatigue—are performed using SACS V16 software to capture both linear and nonlinear interactions among the soil, piles, and superstructure. The environmental conditions include multi-directional wind, waves, currents, and seismic loads. In the static linear analyses (i, ii, and iii), the overall results confirm that the unity checks (UCs) for structural members, tubular joints, and piles remain below allowable thresholds (UC < 1.0), thus meeting API RP 2A-WSD, AISC, IMCA, and Pemex P.2.0130.01-2015 standards for different load demands. However, these three analyses also show hydrostatic collapse due to water pressure on submerged elements, which is mitigated by installing stiffening rings in the tubular components. The dynamic analyses (ii and iii) reveal how generalized mass and mass participation factors influence structural behavior by generating various vibration modes with different periods. They also include a load comparison under different damping values, selecting the most unfavorable scenario. The nonlinear analyses (iv and v) provide collapse factors (Cr = 8.53 and RSR = 2.68) that exceed the minimum requirements; these analyses pinpoint the onset of plasticization in specific elements, identify their collapse mechanism, and illustrate corresponding load–displacement curves. Finally, spectral fatigue assessments indicate that most tubular joints meet or exceed their design life, except for one joint (node 370). This joint’s service life extends from 9.3 years to 27.0 years by applying a burr grinding weld-profiling technique, making it compliant with the fatigue criteria. By systematically combining linear, nonlinear, and fatigue-based analyses, the proposed framework enables robust multi-hazard verification of marine platforms. It provides operators and engineers with clear strategies for reinforcing existing structures and guiding future developments to ensure safe long-term performance. Full article

Post-earthquake fires (PEFs) pose a significant secondary hazard in earthquake-prone regions, compounding the destruction caused by seismic events and threatening structural safety. This review explores the interplay between seismic damage and fire resistance, focusing on ignition sources such as damaged utility systems and overturned appliances, and their cascading effects on structural integrity. Advanced performance-based design approaches are evaluated, emphasizing the integration of probabilistic risk assessments, sequential analysis, and hybrid fire simulations to address multi-hazard scenarios. Key findings of current studies reveal that seismic damage, including spalling, cracking, and loss of fireproofing, substantially reduces the fire resistance of materials like steel and reinforced concrete, exacerbating structural vulnerabilities. Despite advancements, critical gaps persist in experimental data, probabilistic modeling, and comprehensive performance-based design guidelines for PEF scenarios. Addressing these deficiencies requires enhanced data collection, improved modeling techniques, and the integration of PEF considerations into building codes. This study provides a comprehensive review of PEF damage assessment and underscores the need for a holistic, multi-hazard design paradigm to enhance structural resilience and ensure safety in regions subject to seismic and fire risks. These insights provide a foundation for future research and practical applications aimed at mitigating the compounded effects of earthquakes and fires. Full article

In coastal areas, the presence of concrete cracks provides pathways for hazardous ions to ingress from the exterior into the interior of concrete, while the migration of the ions further accelerates concrete deterioration and causes durability problems. The incorporation of graphene oxide (GO) into concrete can inhibit crack initiation and development starting at the nanoscale, improving the concrete microstructure, thereby affecting concrete’s resistance to hazardous ion transport and the resulting deterioration. In this study, a multi-scale transport model for cementitious materials with a GO admixture was established to predict the resistance to hazardous ions. Based on the determination of hydration types and hydration kinetics, microstructure modeling was conducted at three scales, the sub-microscale, microscale, and mesoscale, upon which transport property simulations were performed. At the microscale, the effects of both the cement paste matrix and the interfacial transition zone (ITZ) were considered. Through the simulation, it was found that the addition of GO reduced the duration of the induction period and increased the rate of hydration development after the induction period. Moreover, the incorporation of GO could reduce the porosity of cementitious materials at all simulation scales at both early and later ages. At the microscale, it improved the pore structure of the cement matrix and ITZ by reducing large pores and increasing small pores. At all three simulation scales, GO could increase the diffusion tortuosity in hydration products, suppress ion transport, and improve the resistance to hazardous ions of cementitious materials. Full article

The European Ground Motion Service (EGMS) and geospatial data are integrated in this paper to evaluate ground deformation and its effects on critical infrastructures in the Preveza Regional Unit. The EGMS, a new service of the Copernicus Land Monitoring Service, employs information from the C-band Synthetic Aperture Radar (SAR)-equipped Sentinel-1A and Sentinel-1B satellites. This allows for the millimeter-scale measurement of ground motion, which is essential for assessing anthropogenic and natural hazards. The study examines ground displacement from 2018 to 2022 using multi-temporal Synthetic Aperture Radar Interferometry (MTInSAR). The Regional Unit of Preveza was selected for study area. According to the investigation, the area’s East–West Mean Velocity Displacement varies between 22.5 mm/y and −37.7 mm/y, while the Vertical Mean Velocity Displacement ranges from 16 mm/y to −39.3 mm/y. Persistent Scatterers (PSs) and Distributed Scatterers are the sources of these measurements. This research focuses on assessing the impact of ground deformation on 21 school units, 2 health centers, 1 hospital, 4 bridges and 1 dam. The findings provide valuable insights for local authorities and other stakeholders, who will greatly benefit from the information gathered from this study, which will lay the groundwork for wise decision-making and the creation of practical plans to strengthen the resistance of critical infrastructures to ground motion. Full article

Transmission lines are usually located outdoors and are subjected to wind loads year-round. When a fire occurs, transmission towers are exposed to the combined effects of fire and wind loads. This paper investigates the impact of high temperatures on the bearing capacity of transmission tower-line systems under wind load and explores the effects of uneven horizontal spacing distribution and changes in the elevation of the target tower on the bearing capacity of the tower-line system. The failure criteria for transmission tower components at high temperatures were determined by considering the constitutive relationship of steel at ambient temperature and the variation patterns in material strength and elastic modulus with temperature. A finite element model of the transmission tower-line system was established using ABAQUS (2023). This paper studied the effects of temperature, uneven horizontal spacing distribution, and changes in the elevation of the target tower on the response of the transmission tower-line system by comparing collapse-resisting wind speeds and collapse processes under various conditions. The research indicates that the load-bearing capacity of the transmission tower-line system decreases as temperature increases. When the temperature exceeds 400 °C, the collapse-resisting wind speed of the transmission tower drops sharply. At temperatures above 600 °C, the transmission tower may collapse even at the annual average wind speed. In addition, the uneven horizontal spacing distribution and changes in the elevation of the target tower have an adverse effect on the stability of the transmission tower-line system. It is recommended to choose steel materials with higher fire resistance or apply fire-resistant coatings to existing steel, and to avoid extremely uneven spacing distributions and excessively high target tower elevations. Full article

Antimicrobial resistance (AMR) poses a significant global health challenge affecting food safety and development. Residues of antibiotics in food from animal sources, particularly milk, contribute to the development and spread of AMR, alter intestinal microbiota, and potentially lead to allergies, serious health conditions, and environmental and technological problems within the dairy industry. Therefore, this study investigated the residue levels of veterinary drugs from β-lactam antibiotics and tetracyclines in milk and milk products and assessed human health risks. Two hundred milk and milk product samples (pasteurized milk, sterile milk, soft white cheese, and processed cheese, 50 each) were collected from different hospitals in the State of Kuwait and screened for antibiotic residues using a microbial inhibition assay (Delvotest SP-NT) and high-performance liquid chromatography (HPLC). Delvotest SP-NT and HPLC analyses showed that 30, 28, 26, and 24% of the pasteurized milk, sterilized milk, white soft cheese, and processed cheese samples tested positive for antibiotic residues. Forty-eight milk and cheese samples were confirmed as positive by both methods, and six samples initially found to be negative by Delvotest SP-NT were confirmed as positive by HPLC. Multi-antibiotic residues were detected in five samples by using HPLC. The kappa coefficient (0.921; p < 0.0001) revealed complete concordance between the HPLC and Delvotest SP-NT results. Ampicillin was the most abundant residue in the positive samples (31.48%), ranging from 2.44 to 3.89 μg/L, with an overall mean concentration of 3.492 ± 0.094 μg/L, followed by tetracycline and oxytetracycline (27.78% each), ranging from 54.13 to 220.3 μg/L and from 41.55 to 160.7 μg/L, with mean concentrations of 129.477 ± 14.22 and 91.86 ± 9.92 μg/L, respectively. The amoxicillin levels in the samples (12/54; 22.22%) ranged from 3.11 to 5.5 μg/L, with an overall mean concentration of 3.685 ± 0.186 μg/L. The maximum concentrations of ampicillin, amoxicillin, and tetracycline were detected in processed cheese with mean concentrations of 3.89 ± 0.28 µg/L, 3.95 ± 0.15 µg/L, and 170.3 ± 0.27 µg/L, respectively. Pasteurized milk contained the maximum concentrations of oxytetracycline, with a mean concentration of 120.45 ± 0.25 µg/L. The tetracycline residues exceeded the standard maximum residue limits (MRLs; 100 µg/L) in 6% of both pasteurized and sterilized milk samples, and in 4% of processed cheese. Additionally, the oxytetracycline levels in pasteurized milk (6%) and amoxicillin levels in processed cheese (2%) were higher than the permitted MRLs (100 µg/L and 4 µg/L, respectively). Furthermore, the antibiotic residues detected in 12.5% (25/200) of the samples were close to standard permissible MRL limits for ampicillin (5%), amoxicillin and oxytetracycline (3% each), and tetracycline (1.5%). Hazard quotients, which compare the standard acceptable daily intake (ADI) to the estimated daily exposure (EDI), indicated that the overall risk associated with antibiotic residues in these dairy products is low. The EDI was lower than the ADI for the tested antibiotics, indicating an elevated safety margin. While the overall hazard quotients are low, the potential for the development of antibiotic resistance due to long-term exposure to low levels of antibiotics should be considered. Hence, strict regulations and enforcement are necessary to prevent excessive residue levels and to promote responsible antibiotic use in dairy production. Regular monitoring of antibiotic residues in dairy products is essential for ensuring consumer safety. Full article