ABSTRACT Oxygen reduction systems (ORS) are protection systems, with a design protection objective to limit fire spread beyond the point of ignition. Research has shown that the prescriptive design methods, in VdS 3527, EN 16750, and ISO 20338, are not appropriate as prescriptive design methods as they result in insufficient protection levels. In this paper, two design approaches for ORS for warehouse applications have been developed to address the lack of robust design methods. One design approach was aimed at creating a robust prescriptive method for determination of design oxygen concentrations for ORS. Such a method needs to cover a vast majority of storage configurations and ignition sources. The need to consider intentional fires is also discussed in this paper, as these fires are common in warehouses. The prescriptive method is based on the limiting oxygen concentration for fire propagation (LOC FP ) determined by large‐scale testing performed by Factory Mutual Insurance Company (FM) complemented with a procedure using the Controlled Atmosphere Cone Calorimeter (CACC). The second design approach was aimed at creating a performance‐based design framework for specific applications. The framework is based on an in‐depth analysis of the stored goods, storage configuration, and possible ignition sources. If the specific application is comparable to the large‐scale test setup, and the combination of factors indicates favorable conditions potentially allowing an easement in the design concentration for the system compared to the prescriptive method, variation of the large‐scale testing is recommended to determine design oxygen concentrations. If the specific application is considerably different to the large‐scale test setup, by FM, a completely new large‐scale test needs to be developed to determine design concentrations.
ABSTRACT Modular buildings have gained popularity as a sustainable building solution. However, the uncertainty of fire spread through vertical cavity spaces in such buildings has become a concern. Therefore, this study aims to fill the gap in fire behaviour within vertical cavity spaces. First, an experiment was conducted using a parallel panel arrangement to simulate a cavity fire. It was later modelled in the Fire Dynamics Simulator and validated with experimental results. Later, the model was further validated with data in the literature. Then, a parametric study was conducted for a cavity width ranging from 25 to 200 mm and for the heat release rates of 10 and 40 kW. The simulated cavity fires resulted in a flame extension of up to 8.9 times and a plume flow velocity of up to 2.0 times compared to open fire scenarios. The cavity width was mainly identified to be inversely proportional to the considered fire properties. However, under a 40 kW fire, reducing the cavity width from 50 to 25 mm reduced incident radiative heat flux, cavity internal surface temperature, and flow velocity maximum up to 74%, 44%, and 48%, respectively. A set of empirical equations was developed to predict steady‐state cavity fire behaviour. Finally, the overall fire severity level variation with the cavity width is presented.
Fire-resistant steel (FRS) is rapidly transforming modern construction by significantly enhancing structural resilience during and after fire events. Unlike normal structural steel (NSS), FRS exhibits exceptional mechanical performance at elevated temperatures, yet its behaviour under extreme heat and subsequent cooling remains insufficiently understood. This study delivers a thorough experimental investigation of 350-grade FRS subjected to high temperatures between 500 degrees C and 1000 degrees C, followed by cooling via air and water. Through detailed tensile testing at elevated temperatures and after cooling, key mechanical properties, including yield strength, ultimate strength, Young's modulus and ductility, are quantified to reveal critical performance trends. Results demonstrate that FRS retains much of its strength up to 500 degrees C, contrasting sharply with NSS, but degrades significantly beyond 600 degrees C. Interestingly, post-fire tests highlight the pivotal influence of cooling conditions: specimens cooled in air exhibit strength losses beyond 800 degrees C, whereas water-cooled specimens show strength gains accompanied by reduced ductility. This dichotomy underscores the vital role of cooling regimes in shaping residual structural capacity. Complementary microstructural analyses using scanning electron microscopy (SEM) reveal phase transformations that directly correlate with these mechanical changes, offering new insights into the metallurgical mechanisms driving FRS behaviour after fire exposure. Collectively, these findings deepen our understanding of FRS post-fire performance and pave the way for more resilient, fire-safe structural designs.
Urban tunnel fires often produce huge smoke and cause serious consequences. The temperature attenuation of fume in fire is very important for fire prevention and rescue. In this paper, a 1/15 reduced-size tunnel test platform is utilized to probe the impact of blockage on longitudinal temperature attenuation in the tunnel under the action of the unpowered ventilation cap. The results demonstrate that the tunnel with the unpowered ventilation cap has a higher overall longitudinal temperature and a greater longitudinal temperature attenuation coefficient than the tunnel lacking the unpowered ventilation cap. In light of the experimental conclusions, the forecasting model of the maximum ceiling temperature is improved by introducing correlation factors, which indicate an excellent correlation with the current experimental conclusions. The research outcomes have paramount significance for fire rescue and safety prevention and have certain reference values for the layout of ventilation devices in tunnels.
Cables are laid tightly in the tunnel, which are an important part of modern power transmission infrastructure. Large power transmission and cable aging can cause cable fires easily, and high fire smoke temperature threatens the stability of tunnel structure, meanwhile smoke toxicity causes evacuees poisoning in the tunnel. The combustion performance including the ignite time (TTI), heat release rate (HRR), critical heat flux, fire performance index (FPI), fire growth index (FGI), and smoke production about ZR-Y44JV cable used in tunnels are investigated by cone calorimeter and multifunctional flue gas analyzer. The cable aging time and temperature in experiments are determined based on the thermal aging mechanism of cable sheath and cable insulation. The increase of aging time leads to flash ignition and the increase of ignition time and changes the HRR curve, wherein the plateau stage occurs after the second heat release peak, and the initial peak PHRR1 decreases firstly and then increases. Due to the early pyrolysis, the mass loss of cable combustion changes earlier than the initial HRR change point. The occurrence time of the peak mass loss rate (MLR) is delayed firstly and then advanced with the increasing cable aging time, and the maximum MLR peak time is earlier than that of the unaged cable. It is verified that the aging ZR-YJV cable is still suitable for the hot thickness material model. The fire performance index and fire growth index of the cable are calculated and show that the fire hazard decreases firstly and then increases.
