The heat release rate (HRR) is the most critical parameter in characterizing the fire behavior and thermal effects of a burning item. However, traditional fire calorimetry methods are not applicable ...due to the lack of equipment in most fire scenarios. This work explores the real-time fire heat release rate prediction by using fire scene images and deep learning algorithms. A big database of 112 fire tests from the NIST Fire Calorimetry Database is formed, and 69,662 fire scene images labeled by their transient heat release rate are adopted to train the deep learning model. The fire tests conducted in the lab environment and the real fire events are used to validate and demonstrate the reliability of the trained model. Results show that regardless of the fire sources, background, light conditions, and camera settings, the proposed AI-image fire calorimetry method can well identify the transient fire heat release rate using only fire scene images. This work demonstrates that the deep learning algorithms can provide an alternative method to measure the fire HRR when traditional calorimetric methods cannot be used, which shows great potential in smart firefighting applications.
This article discusses fundamental issues associated with the functional reliability of selected fire alarm systems (FASs) in operation during building fires. FASs operate under diverse external or ...internal natural environmental conditions, and the operational process of FAS should take into account the impacts of physical phenomena that occur during fires. Their operation is associated with the constant provision of reliability. FAS designers should also consider the system’s reliability when developing fire control matrices, tables, algorithms, or scenarios. All functions arising from an FAS control matrix should be implemented with a permissible reliability level, RDPN(t), prior to, as well as during, a fire. This should be assigned to the controls saved in the fire alarm control unit (FCP). This article presents the process by which high temperatures generated during a fire impact the reliability of FAS functioning. It was developed considering selected critical paths for a specific scenario and the control matrix for an FAS. Such assumptions make it possible to determine the impact of various temperatures generated during a fire on the reliability of an FAS. To this end, the authors reviewed that the waveform of the R(t) function changes for a given FAS over time, Δt, and then determined the fitness paths. The critical paths are located within the fire detection and suppression activation process, using FAS or fixed extinguishing devices (FEDs), and the paths were modeled with acceptable and unacceptable technical states. The last section of this article defines a model and graph for the operational process of a selected FAS, the analysis of which enables conclusions to be drawn that can be employed in the design and implementation stages.
Recently, preparation and preventive measures against disasters that can affect the public infrastructure have emerged as a major issue worldwide. Cable-stayed bridges are one of the important ...infrastructures, damage to which may lead to significant casualties and economic loss in the event of a disaster. Fire accidents involving cable-stayed bridges can cause considerable damage to the structures. In this study, numerical analysis was performed to evaluate the effects of fire on cable-stayed bridges. In previous studies, a fire intensity model (FIM) was proposed to simulate cable-stayed bridges' fire that is an open environment. Heat transfer analysis (HTA) and structural analysis were performed using the proposed model. Although the results of HTA presented that higher temperature rises were observed in cables with smaller cross-sections, the structural behavior of the bridge demonstrated vulnerability when a fire occurred near any cable locations that would greatly affect the behavior of the bridge in the event of damage. Based on fire analysis conducted in this study, it is expected that the findings will enable indirect evaluations of fire damage to cable-stayed bridges.
In nuclear power plant fire probabilistic risk assessment (FPRA), numerous single-event fire scenarios are analyzed for risk quantification. The analysis results, however, are often subject to the ...allocation of project resource such as personnel, time and budget, and most importantly, the judgement of analysts. Through repetitive detailed simulation and quantification, the risk of a fire compartment can be modulated in accordance to the expectations of analysts, leading to the misleading risk significance of a fire compartment and weakened credibility of its risk ranking. In view of the unintentional bias in the conventional FPRA, this study aims at providing an objective, dependable risk ranking that reflects areas of high fire risks, and thereby the personnel in the plant can act accordingly. Here, a computational systematic procedure was constructed to consistently simulate the development of all fire scenarios. Through batch-processing, fire scenarios are disintegrated into parts for analysis and quantification. Importantly, details of a fire scenario are kept to the extent that an in-depth research on fire scenario quantification can be proceeded further in the future.
Reinforced concrete (RC) columns, as a main vertical load-bearing structural component, may be seriously damaged in the event of fire and explosion accidents, thereby affecting the safety of the ...building. In the current work, the lateral impact resistance of RC columns under two fire scenarios (at high temperature or after cooling from high temperature) is discussed using a 3D mesoscopic model. In the modeling process, the heterogeneity of concrete and the bond-slip behavior between longitudinal reinforcement and concrete were taken into account. In addition, the differences in impact resistance of RC columns at high temperature and after cooling with different fire durations were analyzed, and some quantitative conclusions were given. The results show that the mesoscopic numerical model considering the relative slip of steel bar and concrete can reasonably reflect the mechanical response of the RC column under impact load or fire. Exposure to the same fire duration, the impact resistance of the RC column at high temperature is weaker than that after cooling due to the severe deterioration of material mechanical properties at high temperature. The damaged area and the maximum plastic strain of the column increased as the fire duration increased. The mid-span peak and residual deflection of columns increase linearly with the increase of fire duration. Under the same fire scenario, the peak and residual impact force of the column increases nonlinearly with the fire duration, while the peak reaction force decreases linearly. The fire scene has little effect on the axial force, shear force and bending moment of the RC column under the same fire duration. In addition, the mechanical behavior of the column ends and mid-span areas need to be considered in the design due to their obvious changes in internal forces.
•Critical analysis of three ship accidents identifies key learning points and similarities with the process sector.•A consequence-based approach to water-use planning in connection with cruise ship ...activity is proposed.•Anchorage activity design is based on the release scale and the reaction time scale at the environmentally vulnerable receptor.•By proper spill and fire scenarios modelling, emergency planning can reduce environmental risk in a sensitive area.
Even if safety in the shipping industry improved significantly over the last decades, by novel design and construction techniques, driven by technological, cultural and regulation improvements, recent passenger ship accidents emphasized that significant safety challenges still remain. The modern trend towards large cruise ships can pose a serious threat in terms of both people evacuation/rescue and potential impact on sensible environmental targets. This paper firstly presents a critical analysis of three passenger ship accidents, identifying main similarities with the process sector and relevant learning points. Secondly, the study approaches risk evaluation, acceptance criteria and sea use planning in connection with cruise activity, referring to the worldwide known sensible area of Portofino (Italy). By utilizing numerical methods, the study develops a consequence-based framework incorporating the effects, the hazardous distance and the reaction time scale, related to fuel spill and fire scenarios with smoke spreading. The results evidence that the approach can be a powerful tool to design optimal ship route and temporary docking points for cruise tourism, balancing economic issues and mitigating physical impact to sensitive biological communities. Additionally, it can provide a technical basis for setting-up emergency planning, with appropriate response equipment and thus minimizing coastal impact from a spill.
Die EN 1993‐1‐2 sieht für die Bemessung von Stahlkonstruktionen im Brandfall unterschiedliche Nachweisformate vor. In diesem Beitrag wird eine Level 3‐Analyse nach DIN EN 1993‐1‐2 anhand eines ...konkreten Beispiels vorgestellt. Die betrachtete Industriehalle mit einer Grundrissfläche von ca. 8000 m2, einer Höhe von 19,0 m und schweren Kranlasten von bis zu 200 t Nutzlast war für eine Feuerwiderstandsdauer von 30 min (R30) zu bemessen und nachzuweisen. Hierfür sollte die Einheits‐Temperatur‐Zeit‐Kurve (ETK) 1 angesetzt werden. Vom Tragwerksplaner wurde die Heißbemessungssoftware VULCAN 3 eingesetzt und für die unabhängige Vergleichsrechnung durch den Prüfingenieur das Softwarepaket SAFIR 4. Die maßgebenden Verbindungen wurden per Handrechnung nach DIN EN 1993‐1‐2, Anhang D nachgewiesen. Durch beide Berechnungen konnte eine ausreichende Feuerwiderstandsdauer von 30 min für die Stahlkonstruktion aufgezeigt werden, so dass auf einen konstruktiven Brandschutz der Stahlkonstruktion komplett verzichtet werden konnte. Der nachfolgende Beitrag beschreibt die Vorgehensweise bei der Bemessung und Prüfung, das angewandte Konzept der Teilmodelle und die Berechnung der maßgebenden Anschlüsse. Während der Berechnung zeigte sich, dass der Ansatz eines Vollbrandes mit einem Brandverlauf nach ETK – im konkreten Fall – nicht nur ein extrem unrealistisches Brandszenario darstellt, sondern auch zu erheblichen numerischen Schwierigkeiten bei der Tragwerkssimulation führte. Die Anwendung von “Worst‐Case”‐Naturbrandszenarien wäre hierfür vorzuziehen und würde mehr Erkenntnis über das tatsächliche Verhalten der Tragstruktur im Brandfall liefern.
Der Inhalt des nachfolgenden Beitrags wurde bereits auf verschiedenen Konferenzen vorgestellt und beruht auf den Quellen 10 und 11.
Fire design for steel structures – Level 3 application of an industrial building according to DIN EN 1993‐1‐2. The paper presents a Level 3 application of EN 1993‐1‐2 2 for an industrial building in Germany. Due to national building regulations the fire design of a large steel hall (8000 m2 area, 19,0 m height and heavy load cranes with service loads up to 200 t) had to be designed for R30 using the ISO‐fire. The design was performed by using the software package VULCAN 3. For independent checking the prove engineers used the software SAFIR 4 to partially reassess the building. The connections were designed via hand calculation according to EN 1993‐1‐2. Both designs show, that 30 minutes fire resistance could be achieved. During the fire design it became obvious, that, caused by the ISO‐fire scenario 1, the structural response became highly non‐linear, which complicated the assessment. The paper describes the process of design and prove engineering, the concept of sub‐modeling, which was used for the design, and the design of main connections. A major experience of the project was that the application of Level 3 calculation methods in combination with the standard ISO‐fire curve is suboptimal. The application of worst case realistic natural fires is preferable and will lead to a more detailed knowledge about the behavior of the structure in fire.
This study aims to develop a computational fluid dynamics (CFD)-based framework to assess the thermal behavior of reinforced concrete (RC) structures with non-uniformly distributed fire damage. To ...achieve this, a CFD model that can predict fire-induced temperature was validated using experimental data of an RC column specimen obtained from an existing study. It was then extended to develop the CFD model of an RC building frame to investigate the extent and pattern of damage to its columns and beams under various fire scenarios, combinations of fire intensity, ventilation coefficient, and fire source locations. The non-uniform temperature distributions of the columns and beams were used to modify the stress–strain curve of concrete and rebar and to perform a moment–curvature analysis to evaluate their residual flexural strength. The computed flexural strengths were compared with those obtained from existing design guidelines. The guidelines were determined to be extremely cautious compared to the results of the proposed method.
•Developed a framework for fire scenario-based damage assessment of RC structures.•Validated a CFD modeling approach using experimental data of an RC column.•Examined the thermal behavior of the case-study RC frame under various fire scenarios.•Estimated the residual flexural strength of fire-damaged RC columns and beams.•Compared flexural strengths from the CFD analysis and existing design guidelines.
The complex responses of the building under fire condition lead to difficult realization of structural fire-resistance design. By identifying the weakness areas, the defined most adverse scenario of ...the structural fire-resistance design has practical significance. In this paper, the characteristics of fire load, steel at elevated temperature and failure modes of steel beam and column in fire test, were discussed to determine that the damage consequences of steel components under fire were equivalent to component fracture. Meanwhile, the calculation method of joint well-formedness after component failure was given to recognize the failure mode of steel frame structure under fire condition based on structural vulnerability theory (SVT). Then, the most adverse fire scenario of the steel frame structure fire-resistance design under the conditions of single component failure and component failure continuously were analysed. The calculation method of the most adverse fire scenario based on the structural SVT was proposed. According to the failure mode identified by the SVT, the most adverse fire scenario was that the component with the minimum damage pattern subjected to fire in the condition of a single component failure occurred. When the component failed continuously, the components induced the maximum damage pattern (the vulnerability index was the largest) were the key components and such components exposed to fire was the most adverse fire scenario. Finally, two calculation models-6-story 4-span planar steel frame and 3D CFS composite shear wall structures-were selected to verify the proposed calculation of the most adverse fire scenarios. It was concluded that the proposed calculation method could reduce the number of fire scenarios that need to be calculated for design and was suitable for application to performance-based fire resistance design.
