Fire Design Research Articles

Determining the stability of a fire truck tanker against overturning while driving through crossed forest terrain

The object of this study is to consider dynamic processes in the tank of a fire truck with different levels of water filling. The task to be solved is to determine the data on the fluctuation of the center of mass of a dynamic system, which consists of the water tank of a fire truck tanker truck, when it moves through rough forest terrain at different speeds. The data make it possible to predict the danger of a fire truck tipping over. In the process of solving the task, an estimation model of a fire truck tanker truck was built together with a water tank, using the LS-Dyna dynamic systems simulation software package. In order to reproduce the dynamic impact on the fire truck tanker with the water capacity exerted by the relief of the rugged forest area, the time dependences of the angles of current position of the fire truck tanker – roll angle, yaw, and pitch – were established. The resulting dependences were used as boundary conditions to reproduce the dynamic influence of the terrain. The turning angles of the water tank of a fire truck were determined depending on the unevenness of the terrain, the geometry of which was calculated by a pseudo-random number generator. Using the explicit method for integrating the dynamics equations, implemented in the code of the LS-Dyna software package, the patterns of fluctuations of the center of mass of the water tank of the fire truck tanker depending on the level of filling and speed of movement were defined. Using results from the mathematical modeling of dynamic processes in the fire truck tanker, a numerical algorithm was developed for this fire truck tanker to maintain its stability against overturning. Therefore, the results of this study have a direct practical application in the field of fire truck tanker design safety and could be used to improve and devise new technologies in this field

Strengthening Reinforced Concrete Members Using FRP—Evaluating Fire Performance, Challenges, and Future Research Directions: A State-of-the-Art Review

Fiber-reinforced polymer (FRP) composites are increasingly used in civil engineering for strengthening and repairing existing reinforced concrete (RC) members using externally bonded reinforcement (EBR) and near-surface mounted (NSM) methods. However, the fire performance of FRP-strengthened RC members has been an important issue that should be properly considered in the fire safety design process since FRP composites exhibit significant performance degradation at elevated temperatures. This paper aims to review studies on the fire performance of FRP-strengthened RC members based on the existing research results presented in the literature to provide a comprehensive understanding of key factors influencing the structural behavior of FRP-strengthened RC members under fire conditions. It provides an overview of FRP composite material properties, such as their mechanical and thermal behavior and bond characteristics between FRP-to-concrete interfaces at elevated temperatures. Additionally, this paper reviews experimental and numerical research conducted on FRP-strengthened RC members, examining load-carrying capacities and fire endurance ratings. Finally, this review will provide existing fire resistance design methods as well as simple design methods for temperature prediction.

Simplified calculation methods of verification for fire design of concrete structures

Simplified calculation methods of verification for fire design of concrete structures

Mechanical properties of bridge steel Q420qE at elevated temperatures

High-temperature mechanical properties of bridge steels, which were rarely investigated, are the foundation for fire resistance analysis and design of bridges. This study investigates the high temperature mechanical properties of Q420qE bridge steel by using steady-state tensile test method. Results indicate that this steel shows no yield plateau at both room temperature and elevated temperatures. Compared with the same grade structural steels, the decrease in elastic modulus and yield strength of Q420qE with increasing temperature are slower. However, the decrease of ultimate strength is more rapid, with a maximum difference on reduction factor being about 0.327 (41.92 %). The mainstream fire resistance design standards exhibit limitations in predicting the high temperature mechanical properties of Q420qE steel. Furthermore, predictive equations of mechanical property reduction factors of Q420qE at elevated temperatures were proposed, and constitutive model of Q420qE at elevated temperatures was recommended.

Study on Smoke Characteristics in Cavern Complexes of Pumped-Storage Power Stations

The underground power houses of pumped-storage power stations (PSPSs) are highly complex, with interconnected and multidimensional structures, including various tunnels, such as the main and auxiliary power houses (MAPH), main transformer tunnel (MTT), tailrace gate tunnel (TGT), access tunnels (ATs), cable tunnels (CTs) etc. During intensive civil construction and electromechanical installation, fire risk becomes particularly prominent. Current research mainly examines fire incidents within individual tunnels, lacking comprehensive analyses of smoke spread across the entire cavern network. Therefore, in this study, a numerical model of a cavern complex in a PSPS was established to analyze smoke behavior and temperature distribution under various fire scenarios. The results indicated that when a fire occurred in the MAPH, the fire risk was relatively higher compared to fires in other places. Using the example of smoke spread from the MAPH to the MTT, the smoke spread process through key connecting caverns was analyzed. Initially, the temperature and velocity were stable, and the CTs and traffic cable tunnel in the auxiliary powerhouse (TCTAP) were the main smoke paths. After 7 min, the heat release rate (HRR) became stable, and CTs and ATs became the main paths for smoke spread, which could provide a reference for improving fire design in underground cavern systems.

Extension of the Continuous Strength Method to the design of steel I-sections in fire

This paper presents an investigation into the extension of the Continuous Strength Method (CSM) to the design of steel I-sections at elevated temperatures. Structural response of 21375 high strength and normal strength steel I-sections at elevated temperatures is considered, taking into account a very broad range of cross-section geometries and cross-section slendernesses as well as different elevated temperature levels and steel grades which include both high strength S690 and S460 steel grades and normal strength S355, S275 and S235 steel grades. The implementation of the CSM for the fire design of steel I-sections is set out. The accuracy of the CSM against that of the provisions of the European structural steel fire design standard EN 1993-1-2 and its upcoming version prEN 1993-1-2 for the ultimate resistance predictions of steel I-sections at elevated temperatures is assessed. It is shown that in comparison to the elevated temperature cross-section design provisions of EN 1993-1-2 and prEN 1993-1-2, the CSM leads to a significantly improved level of accuracy and consistency in the ultimate strength predictions of steel I-sections at elevated temperatures.

Development of a thermoplastic constitutive model for steel based on the generalized Mises yield criterion

Steel is widely used in building structures, and the constitutive model that describes the steel's response to load is an essential component of structural mechanics analysis. This paper aims to investigate the thermoplastic behavior of steel at elevated temperatures. Based on the classical elastoplastic mechanics framework, this study introduces a generalized Mises yield criterion derived from energy theory, which takes into account the temperature effect. In conjunction with relevant assumptions, hardening condition, flow rule, the generalized Hooke's law, and consistency condition, we derive a novel incremental thermoplastic constitutive model for steel. And the new thermoplastic constitutive model's rationality is further verified by utilizing high-temperature steady-state tensile test data. It is encouraging that this new model can accurately describe the mechanical behavior of steel in high-temperature environment such as fire, which is of significant importance for fire safety design of building structures.

New in assessing the fire resistance of reconstructed reinforced concrete ribbed building panel

The article describes the innovative application of a methodology for assessing the design fire resistance of a reconstructed reinforced concrete ribbed floor panel based on the criterion of the occurrence of a limit state based on loss of load-bearing capacity. In this case, the fire resistance limit of a bending element is established without thermal force destruction based on a set of single quality indicators of structural concrete and reinforcing steel, which simplifies engineering calculations and reduces the cost of expensive experiments. The results of a study of the influence of the geometric dimensions of a reconstructed reinforced concrete ribbed panel, the heating scheme of the design section in fire conditions, the placement of the main and additional reinforcement in the design section, the depth of the cores of the main and additional reinforcement and the degree of its fire protection, the thermal diffusion coefficient of structural concrete, the magnitude of the test load on the panel are presented. and the intensity of stress in the rods of longitudinal working reinforcement to the design fire resistance indicator, which is established based on the loss of load-bearing capacity. The use of the new proposed technical solution makes it possible to determine the design fire resistance of a reconstructed reinforced concrete ribbed panel without natural thermal force effects, simplifies engineering calculations, increases the reliability of statistical quality control of reinforced concrete materials and non-destructive tests, and reduces experimental costs.

Experimental study on radiative heat flux from annular pool fires under the cross airflow

This paper investigates the radiative heat flux of annular pool fires under cross airflow (0–5 m/s), a configuration that has been underexplored in fire safety research despite its relevance in industrial fire hazards. Results show that radiative heat flux decreases with increasing distance from the fire source but increases with higher cross airflow speeds and larger annular pool diameters (Din/Dout). Existing models overestimate radiative heat flux in annular pool fires due to the underrepresented hollow flame region. A new modified triangular prism radiation model was developed based on the similarity criterion of annular pool fires. An extensive comparative analysis was further conducted, encompassing a wide array of experimental configurations documented in the literature, characterized by varying diameters spanning from 0.1 m to 0.7 m and cross wind velocity ranges extending from 0 m/s up to 5 m/s. The results of this comprehensive examination reveal a good agreement between the newly established model and the empirical data, thereby substantiating the model’s universal applicability and robust reliability. The new model will effectively assist industrial facilities in enhancing fire safety design, strengthening thermal hazard prevention and control, and ensuring a higher level of fire safety design.

Optimizing automated compliance checking with ontology-enhanced natural language processing: Case in the fire safety domain

The fire safety compliance checking (FSCC) plays a crucial role in ensuring the quality of fire engineering design and eliminating inherent fire hazards. It requires an objective and rational interpretation of fire regulations. However, the texts of fire regulations are filled with numerous rules related to spatial limitations, which pose a significant challenge in interpreting them. The current method of interpreting these rules mostly relies on manual translation, which is not efficient. To address this issue, this study proposes an innovative automated framework for interpreting rules by combining ontology technology with natural language processing (NLP). Through the utilization of pre-trained language models (PLMs), concepts and relationships are extracted from sentences, a domain-specific ontology is established, spatial knowledge is transformed into language-agnostic tree structures based on the ontology, and the semantic components of spatial relationships are extracted. The tree structure is then mapped to logical clauses based on semantic consistency, thereby improving the efficiency of interpretation. Experimental results demonstrate that the architecture achieves an F1 score of 86.27 for entity extraction and 81.81 for spatial relationship joint extraction tasks, with an accuracy of 96.26% in the formalization of logical rules, highlighting its proficiency in automatically interpreting fire spatial rules. This study offers technical support to enhance public understanding of fire safety management and fire prevention predictions, thereby promoting the intelligent management of the building safety environment.

Local-global buckling interaction in steel I-beams—A European design proposal for the case of fire

This paper presents a comprehensive review of the developments leading to the proposal of European fire design rules for steel beams with thin-walled I-sections. Thin-walled beams are favoured in steel construction due to their structural efficiency, however they are prone to buckle when subjected to in-plane loads, phenomenon which requires a thorough investigation. The focus lies on addressing the interaction between local and global buckling in these members. This study discusses modifications to the Effective Width Method at elevated temperatures, aiming to rectify underestimation of section capacity on certain cross-sections. Additionally, an overview of lateral-torsional buckling resistance is provided, being a new Effective Section Factor proposed to account for its interaction with local buckling. The paper revisits the European fire design proposal, comparing the improvements of the existing Eurocode 3 Part 1–2 (EN1993-1-2:2005) relative to the recent second generation of Part 1–2 of Eurocode 3 (FprEN1993-1-2:2023) through an extensive numerical study. Limitations and future research directions are also discussed, such as dependency on the section classification and broadening the application scope of these rules to higher steel grades.

Redefining competency in fire safe design

The Grenfell Tower Inquiry reports paint a terrifying image of the construction industry, as an ensemble, and particularly, in all matters pertaining fire safe design. Carefully look at these reports will help define responsibilities and legal procedures will do this for many years to come. Nevertheless, it is also essential to address the future and how we evolve our practises and professionals in a manner that prevents a tragedy of this nature to happen again. For this purpose, a key message needs to be emphasized: a functional requirements system of regulation will not deliver what society expects unless a rigorous competency framework is created and implemented for all professionals involved in fire safety. The means to create and put in practise such a framework is at the core of the Grenfell Tower Inquiry Phase 2 recommendations.

Digitized fuel load survey in commercial and university office buildings for fire safety assessment

Fuel load significantly affects fire development in compartments, and its design value derives from the statistical results of numerous surveys. This work enhances the fuel load database by employing a digitized survey method to assess 27 university and commercial offices in Hong Kong and Mainland, China. The results revealed significant differences in fuel load densities: university offices averaged 382 MJ/m2 (SD: 297 MJ/m2) and commercial offices averaged 1804 MJ/m2 (SD: 1319 MJ/m2). Moreover, it proposed an online questionnaire method to overcome onsite access limitations. Furthermore, it identified higher fuel load densities in commercial offices due to higher paper-made content and greater occupancy density than university offices. The fuel load of university offices was lower than that in previous surveys and design codes, while commercial fuel load was higher. Notably, there is an increasing tendency of fuel load density and plastic combustible composition over the years. Additionally, it considers that Gompertz distribution better fits cumulative probabilities of fuel load density data with a small sample size. Overall, it provides a valuable database for future fire scenario design, fire codes edition, and fire safety assessment and discusses future collaboration with AI applications.

A deep-learning-based approach for simulating pedestrian turning flow

The applications of artificial intelligence technology in pedestrian and evacuation dynamics research have achieved gratifying progress recent years. Benefiting from the non-linear fitting ability of deep learning algorithm, such learning-based method might have better performance in modeling the individual micro behaviors comparing to traditional pedestrian and evacuation dynamics models. Hence, this paper proposes a deep-learning-based pedestrian dynamics model which can simulate the pedestrian flow in right-angled corridors. The training process is conducted with a deep learning framework composed of two functional layers namely Scene Perception layer (SP layer) and Motion Dynamic layer (MD layer). The input features of the SP layer and MD layer are obtained from a defined ‘sense field’ which captures information about walking facility structures and neighbors. Dataset generated from twelve groups of pedestrian turning flow experiments is used for data training. The initial experiments are further adopted to evaluate the model at both qualitative and quantitative level from pedestrian motion data simulated by trained model. Qualitatively, the simulation results align with the corresponding experiments in terms of fundamental diagrams in different measurement areas and the headway distance-velocity relationship, demonstrating realistic motion characteristics, proper reactions to changeable walking facility structures and collision avoidance tendencies of agents driven by our model. For quantitative evaluation of the model precision, two indicators respectively calculate the duration and trajectory disparities are introduced and both of them yield relatively small values. Moreover, eight groups of external experiments completely independent from training data are introduced to validate the generalization ability of our model, the simulation results are found to match reality well without prior knowledge. The proposed framework presented is a success trial for simulating pedestrian turning flow and have the potential to be adapted to different scenarios. Outcomes presented will be of beneficial guidance for different engineering application such as performance-based fire design and crowd management.

Analysis of Fire Evacuation Scenarios in Children's Cultural Centers

Fires that occur in assembly buildings cause great loss of life and property. Children's cultural centers included in assembly buildings should also be evaluated within this context. Children create an occupant profile in cultural centers, and the internal environment has an excessive fire load, which poses a great risk of fires. In fire evacuation scenarios for children's cultural centers, it is necessary to create appropriate evacuation conditions. In this work, fire safety was analyzed over total evacuation times within occupant-based fire evacuation simulations of a children's cultural center located in Istanbul. The effect of the children's theatre hall located on the top floor on a building's total evacuation time has been studied. The effectiveness of alternative fire escape routes on evacuation time through different evacuation scenarios has been analyzed, and safe evacuation strategies for children's cultural centers have been revealed. As a result of this study, recommendations were presented within performance-based fire evacuation strategies in the design of children's cultural centers. As the future of the countries, fire safety design criteria have been created in children's cultural centers for children to be able to be safe in educational, cultural, and artistic environments.

Advancements to the equivalent compression flange method

AbstractThe simplified method of the equivalent compression flange represents an illustrative and easy‐to‐use engineering model for lateral torsional buckling. The basic concept of the verification procedure has existed since its introduction in the 1950s. It is still frequently used today for preliminary design and application cases where the solution of the ‘correct lateral torsional buckling problem’ is complex and time‐consuming. To adapt the method to the current state of the art, it was further developed in the framework of the Eurocode 3 evolution. This ‘new’ method is part of the second generation of Eurocode 3, Part 1‐1 and is valid for classes 1 to 3 cross sections in major axis bending. The method must be adapted for use in other contexts and for specific applications. Applying the equivalent compression flange verification method to the structural fire design of building structures must consider the temperature‐dependent material properties of steel and their impact on the stability behaviour. Moreover, typical applications for bridge structures, runway beams, and H‐piles in combined walls require additional consideration of class 4 cross sections and various combined loadings, e. g., N–M interaction behaviour. This article presents theoretical studies on extending the simplified method of the equivalent compression flange to meet these demands. Finally, the application of the verification method is demonstrated in working examples.

A Study on the Influence of Mobile Fans on the Smoke Spreading Characteristics of Tunnel Fires

Mobile fans, as flexible and convenient new longitudinal ventilation and smoke extraction equipment for tunnels, demonstrate more significant effectiveness in an emergency response to tunnel fires compared to traditional smoke extraction methods. This study employs computational fluid dynamics simulation methods, selecting two fire scenarios to investigate the effects of fan inclined angles and fan airflow volumes on the longitudinal temperature distribution and smoke back-layering length in tunnels. The results indicate that when using mobile fans for longitudinal ventilation in tunnels, at a lower fan airflow volume, the temperature distribution along the longitudinal axis is nearly symmetrical. The fire source and the fan installed in the upstream are within a certain range, and it is more effective to use the horizontal angle for longitudinal ventilation. As the fan airflow volume increases, the back-layering length significantly decreases (210,000 m3/h < V < 270,000 m3/h). However, as the fan flow volume continues to increase (270,000 m3/h < V < 300,000 m3/h), the reduction in the back-layering length becomes less pronounced, the smoke spread distance of the latter is only 11% of that of the former. Therefore, selecting appropriate fan airflow volumes and fan inclined angles them can effectively enhance the performance of tunnel smoke extraction systems. Moreover, by comparing with traditional fans, we find that mobile fans provide an alternative effective strategy during firefighting by allowing adjustments in distance from the fire source and fan inclination angles, enhancing fire suppression effectiveness while reducing energy losses. The research findings can serve as a reference for tunnel fire prevention design.

Defining a maximum heat release rate probability distribution function for design fires in sprinkler‐protected residential buildings

AbstractIn fire safety engineering analysis of sprinkler‐protected residential buildings, the maximum heat release rate is a key parameter requiring consideration. Several documents provide advice for estimating the heat release rate of a sprinkler‐controlled fire, with a prevailing suggestion that it is fixed upon activation of the first sprinkler. When carrying out deterministic analysis, this requires the engineer to assume fixed fire parameters and consider that sprinklers limit fire growth. To explore these assumptions, the study uses three deterministic models to estimate a sprinkler‐controlled maximum heat release rate for a representative apartment layout. The models include Alpert's correlation, a B‐RISK zone model and a computational fluid dynamics model in the Fire Dynamics Simulator. These deterministic models are compared to a probabilistic model in B‐RISK, where Monte Carlo simulations are used to generate a range of maximum heat release rates from distribution functions for fire and sprinkler properties. An output distribution function is generated with a mean of 296.6 kW and a standard deviation of 503.8 kW, with a lognormal distribution (μ = 5.014, σ = 1.165) estimated as a best‐fit. The deterministic models are estimated to sit in the 92–98 percentile range of this function, indicating that common deterministic assumptions are reasonably conservative. The article concludes with suggesting that, for deterministic analysis, a percentile between the 80th and 99th (340–2640 kW) could be qualitatively selected based on the design objectives, building situation and relative consequence of a fire. Further research is needed to establish guidelines for selecting appropriate percentiles across various building scenarios.

A fire risk pre-warning framework for high-rise buildings based on unascertained method

The growing global interest in preventing and controlling fires in high-rise buildings reflects the increasing significance of this issue today. This research aims to establish an early warning framework for fire risk in high-rise buildings. Firstly, considering the importance of a scientific indicator system for the application of the model, this study combines the event analysis method with the building design fire code to identify 11 key risk factors that have a far-reaching impact on the prevention of fires in high-rise buildings. Based on identifying the risk factors, a high-rise building fire risk warning tree is also established, which scientifically solves the problem of the indicator system of the warning object. Subsequently, in response to the various complex issues arising from the uncertainty of fire occurrence in high-rise buildings, this study adopts the unascertained method to model the fire risk of high-rise buildings for early warning. In addition, the developed methodology was empirically validated through case studies and analyses of empirical data on fire risks in nine representative high-rise buildings. The results of the unascertained method were also compared with the results of the K-means method, from which it was concluded that the unascertained method can predict building fires more accurately. The research results provide a reliable decision support system for fire disaster prevention and control in high-rise buildings.

Computational analysis of wildland fire resistance for transmission line tower

Finite element (FE) analysis of the transmission towers under a fire event and the accompanying wind is presented. Several key aspects (including temperature-dependent non-linear material properties, geometric non-linearity, member eccentricity due to the single-leg bolted connection, and the temperature-dependent connection behaviour in both the axial and the rotational directions) are considered. A quasi-static analysis is also employed in the FE model using the explicit solver available in Abaqus. The member temperature variation during a realistic fire event is derived analytically based on the fire intensity and the resultant vertical gas temperature distribution so that the effect of the realistic wildland fire can be input as a member temperature profile. First, fire design guidance in terms of the most critical heating and wind pattern, as well as the effect of fire-affected heights are provided based on the case study results. Then, further fire analysis is carried out to investigate the most critical fire scenario and to evaluate the vulnerability of the tower during a realistic fire event. Lastly, an evaluation of a commonly used spray-on thermal insulation and its effectiveness in reducing the member temperature and preserving ultimate strength during a catastrophic wildland fire event are presented. The FE simulations revealed that a 45-degree wind associated with partial side heating leads to a more critical degradation of the overall strength, whereas the effect of fire height is less obvious. In terms of the fire scenario, a longer fire duration associated with a slower wind is more critical for the fire resistance/rating.