Standard Fire Tests Research Articles

Fire Protection of Steel Beam by OSB Claddings—A Fire Experiment and Numerical Models

ABSTRACTThis paper presents the results of a standard fire resistance test of a loaded steel beam in a horizontal furnace. The beam was tested in three configurations: (1) unprotected, (2) protected with a single 22 mm layer of oriented strand board, and (3) protected with a double layer of the same cladding. The study also describes the development of a model in Fire Dynamics Simulator to predict the thermal conditions in the furnace and to observe the temperature trends on the beam surface, on the cladding, and at various depths in the cladding. A comparison between calculated and measured temperatures showed good agreement for the unprotected beam. However, for the protected beams, the model underestimated temperatures after 15 and 30 min for the single‐layer and double‐layer protection, respectively. Several potential sources for the discrepancies are identified. The main reason lies probably in the model's inability to correctly account for the effect of gaps in the cladding joints. Future work will focus on improving the accuracy of the model by removing these identified limitations, with particular attention to the behavior of the cladding as a passive fire protection material.

Full-scale hybrid fire test in real-time with multiple degree of freedom

To experimentally assess the fire resistance of civil structures, testing whole structures is very costly but the standard tests on individual structural elements can sometimes be too simplistic, regarding their boundary conditions. Hybrid fire testing offers a promising solution to these limitations, but performing such tests is technically challenging and few full-scale tests have been conducted. Current approaches rely on high-performance sensors and actuator systems, as well as assumptions about the stiffness of the tested element. This paper presents the detailed methodology and results of a full-scale, real-time test with 3 degrees of freedom on a concrete beam. The use of an adaptive controller allowed for maintaining stability and achieving reasonable precision despite the use of relatively low-precision sensors, regular hydraulic actuators, and no assumptions about the tested element’s stiffness. The comparison with the same element tested using a standard fire resistance test demonstrates the usefulness of this technique in achieving a more accurate representation of the performance of the tested element in realistic conditions.

Improving the fire-retardant performance of industrial reactive coatings for steel building structures

The main aim of this study was to determine key factors that regulate fire-retardant effectiveness of intumescent coatings comprising of ammonium polyphosphate, melamine, pentaerythritol, polymer binder. Fulfillment of the research objectives resulted in the development of a coating with R120 fire resistance. The expected service life of the coating is at least 15 years when applied at Z2 type of environmental conditions (indoor use). It was established that in order to provide fire resistance of around R30 it is advisable to use the styrene-acrylic polymers as binders for both water-based and organic-based intumescent systems. The ratio of target components ammonium polyphosphate/melamine/pentaerythritol in such systems should be close to 2/1/1. The coating thickness is to be 0.4–0.5 mm. To achieve higher fire resistance (R60 or more) the coating should include a vinyl acetate derivative as a binder (copolymers with ethylene or vinylversatate). Target components ratio in this case is to be close to 3.5/1/1.5, while the coating thickness should be kept at 1.6–1.8 mm. If the required class of fire resistance is above R120, coating thickness is usually to be kept above 3.5 mm. In order to achieve higher fire resistance, it is advisable to use nano-clay additives and reinforcing fibers in intumescent compositions.The obtained results were used in the development of intumescent coating, which is produced industrially and provides over R120 fire resistance of steel, which was confirmed in standardized full-scale fire tests.

Oil and Gas Structures: Forecasting the Fire Resistance of Steel Structures with Fire Protection under Hydrocarbon Fire Conditions

The hydrocarbon temperature–time curve is widely used instead of the standard curve to describe the temperature in the environment of structural surfaces exposed to fire in oil and gas chemical facilities and tunnels. This paper presents calculations of the ratio of time to reach critical temperatures at different nominal fire curves for steel structures such as bulkheads and columns with different types of fireproofing. The thermophysical properties of the fireproofing materials were obtained by solving the inverse heat conduction problem using computer simulation. It was found that the time interval for reaching critical temperatures in structures with different types of fireproofing in a hydrocarbon fire decreased, on average, by a factor of 1.2–1.7 compared to the results of standard fire tests. For example, for decks and bulkheads with mineral wool fireproofing, the K-factor of the ratio of the time for reaching the critical temperature of steel under the standard curve to the hydrocarbon curve was 1.30–1.62; for plaster, it was 1.56; for cement boards, it was 1.34; for non-combustible coatings, it was 1.38–2.0; and, for epoxy paints, it was 1.71. The recommended values of the K-factor for fire resistance up to 180 min (incl.) were 1.7 and, after 180 min, 1.2. The obtained dependencies would allow fireproofing manufacturers to predict the insulation thickness for expensive hydrocarbon fire experiments if the results of fire tests under standard (cellulosic) conditions are known.

Fire Safety Research Institute Materials and Products database—A resource to support fire modeling

For decades, there has been a need in the fire safety science community for a reliable source of material properties and standard fire test data to accurately represent solid materials in fire models. The project described herein has made advancements in experimental data collection and property determination for a multitude of materials commonly encountered in the built environment for the purpose of making the data easily accessible and to elevate the base knowledge and tools available for all model practitioners and investigators. This article includes a description of the experimental methods, procedures, and estimated uncertainty in the measurements that have been adopted to collect the data necessary to describe common materials in the most advanced comprehensive pyrolysis models. A case study is provided in which all the experiments to characterize polycarbonate are described, analytical procedures and derived properties are presented, and validation of the properties against experimental data is presented.

Fire and post-fire performance of unbonded semi-precast prestressed reinforced concrete beams

The integration of semi-precast concrete beam preparation methods with prestressing structural measures aims to achieve superior mechanical properties while complying with green construction principles. However, the damage mechanism of semi-precast prestressed concrete beams (SP-PCBs) under fire conditions is not clear. In this study, the cross-section temperature distribution, prestressing loss pattern, and residual load-carrying capacity of the SP-PCBs were investigated by conducting standard fire tests. The results show that increasing the thickness of the protective layer of prestressing bars can delay the time of damage by high temperature and thus increase the fire resistance limit of the SP-PCBs. Higher prestressing levels and rebar ratios contribute to the cracking resistance of the SP-PCBs, although the stress loss is obvious. After the fire, the distinct SP-PCBs showed different degrees of reduction in load-carrying capacity and stiffness, but still exhibited excellent fire resistance and avoided brittle damage. Increasing the reinforcing ratio increases the residual load-carrying capacity of the SP-PCBs, while increasing the prestressing level has a relatively small effect. Increasing the height of the post-cast layer slightly reduces the stiffness and ductility of the SP-PCBs, but does not significantly affect the load-bearing capacity. In addition, this paper establishes a theoretical calculation model for the residual load-bearing capacity of the SP-PCBs after the fire, and verifies the accuracy of the model by experimental results, which provides a practical theoretical basis and reference for the design and evaluation of the fire resistance performance of the SP-PCBs.

Relationships between wood properties and fire performance of glulam columns made from six wood species commonly used in China

Glued laminated timber stands as an increasingly favored engineered wood product in low-rise modern timber structures due to its commendable structural performance and carbon sequestration potential. Chinese standards presently fail to differentiate the effects of distinct wood species on the fire resistance of glulam. This study examined the charring rate and residual bearing capacity of glulam columns made from six commonly used wood species in China: poplar, Chinese fir, Douglas fir, hemlock, larch, and spruce. These materials exhibited densities ranging between 390 and 645 kg·m−³. ISO standard fire tests were conducted employing one- and two-adjacent-side fire exposures. Notably, the findings unveiled that high-density glulam columns demonstrated lower charring rates and slower rates of heat penetration. The two-adjacent-side fire configuration induced a corner effect, consequently amplifying the effective charring depth. The results showed a linear relationship between the ratio of diagonal to horizontal charring rate of the columns exposed to the two-adjacent-side fire and wood density. To enhance practical application, a formula was developed, employing the residual section method, to calculate the column's residual bearing capacity post two-adjacent-side fire exposure. This formula incorporates an adjustment depth to accommodate the corner effect, effectively mitigating the reduced wood strength within the pyrolysis zone.

Numerical modelling and investigation of CFS built-up stud walls in fire

Cold-formed steel (CFS) stud walls with the studs made of BC (built-up back-to-back CFS channel) and NC (built-up nested CFS channel) members are likely to be utilised in many applications in CFS building structures. However, the knowledge and understanding related to the thermal and structural behaviour of these improved CFS stud walls under fire exposure and their FRLs (fire resistance levels) are still limited. Although standard fire tests of real-sized walls could show the behaviour and FRL of some BC and NC stud walls, their results are limited because of their high cost and time-consuming nature, and are applicable to only the tested configurations. In this study, thermal and sequentially coupled structural finite element models were established. The validation of these models was achieved using the standard fire test results of real-sized BC, NC and channel stud walls. Later, parametric investigations based on the established models were undertaken to investigate the behaviour and FRLs of load-bearing BC, NC and channel stud walls with or without cavity insulation under varying load ratios. The outcomes from these investigations clarified the superiority of cavity insulated NC stud walls. Details of this study and its outcomes are presented in this paper.

Assessing the Efficacy of Magnesium Hydroxide and Aluminium Hydroxide in Enhancing Flame Retardancy of Natural Fiber

Natural fiber panels have gained attention as sustainable alternatives in various applications, including construction and interior design. Although these fibres are highly valued for their environmental sustainability and acoustic advantages, they are inherently flammable. These panels, when subjected to fire or high-temperature conditions, pose significant safety risks due to their flammability and potential for rapid combustion. This study evaluates the efficacy of various synthetic additives in enhancing the flame retardancy of natural fiber panels. The panels were made by mixing the natural fiber with polyester resin and additives. The experimental setup includes standard fire tests such as ASTM D635 Horizontal Burning and ASTM D3801 Vertical Burning Test. The results show that rice husk demonstrates a slower burning rate when combined with both magnesium hydroxide and aluminium hydroxide, indicating better flame retardancy. Coconut coir outperforms rice husk and sawdust for both magnesium hydroxide and aluminium hydroxide which are 655 s and 640 s respectively in terms of vertical burning. The study showed that magnesium hydroxide is a better flame retardant than aluminium hydroxide. This makes it a promising option for enhancing the fire resistance of natural fiber panels.

Analysis of Paint Properties According to Expandable Graphite and Fire Simulation Research on Firewall Penetration Part.

In this research, we attempted to develop paints that can be applied to various fields such as high-rise building structures and electric vehicle batteries. To minimize damage to life and property in the event of a fire, we attempted to manufacture a highly elastic paint material that can block flames and control smoke spread, and that has additional sound insulation and waterproofing functions. A high-elasticity paint was manufactured by mixing a flame-retardant polyurethane dispersion (PUD) with an acrylic emulsion binder and adding different mass fractions of expandable graphite (EG). The thermal, physical, and morphological properties of the prepared mixed paint were analyzed. The thermal properties of the mixed paint were analyzed and intended to be used as input data (heat transfer coefficient, specific heat capacity) for fire simulation. Output data were used to predict how much the temperature would change depending on the time of fire occurrence. The reason for conducting simulations on the fire stability of paint materials is that the fire stability of paints can be predicted without conducting fire tests. Two hours after the fire broke out, the thermal temperature distribution was analyzed. The temperature distribution was compared with and without mixed paint. Two hours after a fire broke out in a virtual space, it was found that when the mixed paint was applied, the surrounding temperature of the penetration area was lower than when the mixed paint was not applied. Development costs for developing excellent paints can be reduced. Since fire safety can be predicted without actually conducting tests, the time required for product development can be reduced. We are confident that this is a very groundbreaking technology because it allows fire safety simulations for developed products to be conducted in a virtual space by creating an environment similar to actual fire test standards.

Study on mechanical properties and fire resistance of porous ceramic silicone rubber

AbstractPorous ceramic silicone rubber (PCSR) has an excellent ablative resistance because of its strong carbon layer structure after burning. However, as a marine sealant material, it also needs to have better mechanical properties for better application. In this study, PCSR composites were prepared by compounding with different additives and different viscosity base adhesives, and their fire resistance, tensile properties, and bond strength of multiple substrates at different temperatures were investigated and compared. When the ratio of 20,000 to 80,000 viscosity matrix adhesive is 3:7, the material prepared by adding deketoxime crosslinker and silane coupling agent containing amino and epoxy groups together can reach more than 1.4 MPa tensile shear strength at 150°C. Sintering experiments have shown that PCSR composites can still maintain the strength and integrity of the carbon layer structure, and the results of the A‐60 standard fire resistance test for cable and pipe penetration devices have shown that marine PCSR sealants can effectively prevent flame propagation.

Fire behavior of hemp blocks: A biomass-based construction material

Hemp blocks, also known as hempcrete, are eco-friendly and sustainable construction materials composed of hemp, lime, and water. In this study, the fire behaviour and structural performance of hemp-based materials were experimentally investigated. Fire exposure scenarios using raw hemp shives, hemp blocks, and non-load-bearing hemp block walls were examined. Tests conducted include cone calorimeter, bomb calorimeter, standard furnace, heat-transfer rating inducing system (H-TRIS), and small-scale elevated temperature material tests. Hemp shives exhibit ignition with sustained flaming, a relatively high heat release rate (HRR), and a relatively low critical heat flux (CHF). However, the hemp blocks exhibited no flaming ignition, only smouldering combustion, and an HRR an order of magnitude lower. Hemp blocks and hemp shives produced minimal smoke. Hemp blocks charred, and associated discoloration zones have been documented. Tests indicate that limited structural capacity is lost up until 200 °C, whereas at 300 °C, the residual material strength is almost negligible. The hemp block walls maintained their structural stability and integrity for 2 h of standard fire testing. The ambient-temperature compressive strength of the hemp blocks was determined to be 1.0 MPa. This work is the first comprehensive study on the fire behaviour of hemp blocks and highlights their good performance, whereby they are likely to have a limited impact on fire risk in buildings. Plastered walls will have a fire performance exceeding those reported here.

Comparative Study on Interfacial Properties, Foam Stability, and Firefighting Performance of C6 Fluorocarbon Surfactants with Different Hydrophilic Groups.

Liquid fuel is flammable and hazardous, and a pool fire is one of the most serious disasters. Therefore, it is important to develop high-performance firefighting agents. To synthesize aqueous film-forming foam (AFFF) formulations, two C6 short-chain fluorocarbon surfactants Capstone 1157 (FC1157) and sodium perfluorohexylethyl sulfonate (SF852) with different hydrophilic groups were introduced, and three hydrocarbon surfactants sodium dodecyl sulfate (SDS), decyl glucoside (APG0810), and coco glucoside (APG0814) were chosen. The AFFF formulations based on the short-chain fluorocarbon-hydrocarbon compounding system were developed, and the firefighting performance of the formulations was assessed according to the standard pool fire extinction test. The results indicated that amphoteric FC1157 was slightly more effective than anionic SF852 in extinguishing small-scale pool fires and could reduce heat flux more effectively than SF852. Fluorocarbon surfactant FC1157 has been shown to suppress large pool fires much better than SF852, possibly due to its higher foam stability, higher foaming property, lower dynamic surface tension, and lower bubble coarsening rate. Both formulations we studied were more effective than commercial AFFF formulations. A concentration of 0.1-0.3% of FC1157 in an AFFF solution was optimal for extinguishing high-boiling-point oil fires.

Lightweight composite gypsum boards with clay mineral and glass fibre for enhanced fire-resistance

The current strategy for developing fire-resistant gypsum boards is mainly based on adding porous materials. However, these additives are generally weaker in strength due to higher porosity and are usually produced via energy-intensive processes with relatively higher costs. This paper presents a novel strategy to fabricate lightweight fire-resistant composite gypsum boards through the synergistic coupling of naturally abundant clay mineral - palygorskite (0–30 wt%) and cost-effective glass fibre (0.5 wt%). The bulk density of the obtained boards decreases from 1059 (0 wt% palygorskite addition) to 795 kg/m3 (30 wt% palygorskite). Attributed to the higher initial porosity, reduced shrinkage above 650 °C, and the decomposition of CaSO4 above 925 °C to absorb heat, the ambient side temperature of a composite gypsum board after a 90-min standard fire test is reduced significantly by 150 °C. The new board shows a commendable post-fire strength of 0.15 MPa and fewer cracks than commercial products, which are caused by increased porosity and the bridging effect of glass fibre and sintered palygorskite particles. Through the effective integration of in-situ high-temperature X-ray diffraction, thermal mass loss/heat exchange, and thermal dilatometry, the real-time thermal behaviours of composite gypsum boards are characterised, and the microstructure, physical and mechanical properties and fire resistance are investigated.

Evaluating fire resistance of timber columns using explainable machine learning models

The global attention to using timber products as sustainable construction material urges careful assessment of their performance against different hazards, particularly fire. However, the current methods prescribed by design codes for evaluating the fire resistance of timber components tend to underpredict the outcomes of standard fire resistance tests, and lack interpretability due to the use of semi-empirical equations. This study develops explainable data-driven models to predict fire resistance of timber columns using geometry- and material-related properties based on a comprehensive experimental database. Nine different single and ensemble-based machine learning algorithms were trained, and their performance was optimized through rigorous hyperparameter tuning and feature selection. The best models were then interpreted using partial dependence and Shapley plots to infer the underlying relationship between fire resistance and column properties. Lastly, the models’ predictive capabilities were compared to available prescriptive equations. The results show that a random forest-based model provides the best performance with an average ratio of predicted to observed fire resistance of 1.03 on the test set. The random forest prediction is mainly governed by column capacity at ambient temperature, and to a lesser degree, columns’ cross-section dimension. In addition, the partial dependence plots indicate that the effect of density, modulus of elasticity, length, and compressive strength on fire resistance was not notable. Finally, while the considered prescriptive equations consistently underpredict fire resistance, the random forest model provides a consistently accurate and balanced prediction.

Full-scale fire resistance tests of lightweight steel framed floor systems

As cold-formed steel profiles are increasingly used for load-bearing structural systems, their fire design requires specific attention due to their thin-walled nature and high slenderness. In some specific applications such as in storage hall floor systems, these structures are used without sheathing or thermal protection on the fire-exposed side. Yet, there is a lack of data from fire resistance tests on full-scale load-bearing thin-walled steel structures, especially with directly exposed steel. This article describes two standard fire resistance tests on full-scale light gauge steel frame floors made of cold-formed steel lipped channel girders and joists topped by chipboard panels. The experimental program was designed to investigate the fire resistance of the unprotected girders. A specificity of this program was that the girders were subjected to a low load level to probe the ability to achieve without passive fire protection a 30-min fire resistance rating typical for storage hall structures in the Czech Republic. The absence of protection resulted in differences in thermal gradients and bracing compared to common fire tests, as well as a very low degree of utilization leading to an expected failure temperature higher than 800 °C. The results showed that the two floors remained stable during the 30 min with limited deflections, but failed the deflection rate criteria after 24 and 22 min, respectively. Comparison is provided with the calculation methods from the Eurocodes. The presented results provide new data on the response of full-scale, unprotected cold-formed steel floor systems subjected to fire, which can be used to calibrate numerical models and fire design methods outside of the range currently covered by the codes.

Study on the fire performance of novel G550 galvanized steel‐concrete composite slabs

AbstractTo reduce the construction and maintenance difficulties caused by fire proof coatings and reinforcement used in composite structures, 2 new types of steel‐concrete composite slab was proposed combining G550 galvanized steel with re‐entrant sheeting and closed profiled sheeting. 12 full‐scale standard fire tests were conducted to investigate the fire performance of G550 galvanized steel‐concrete composite slabs. Temperature rise within profiled sheeting and concrete are compared for the novel composite slabs. With the development of bearing capacity index, the fire performance of novel G550 galvanized steel‐ concrete composite slabs are analyzed under the same unified standard. Results showed that all the newly developed composite slabs could reach the design requirements for buildings up to 18 m above ground without the use of coatings and reinforcement. And the composite slabs with closed profiled sheeting can reach 120 min fire resistance when bearing capacity index is less than approximately 0.1 and are suitable for application in high‐rise buildings.

Estimation of effective thermophysical properties of firestopping sealants: Methodology and case study

Firestops have been widely applied to protect nonstructural service elements which penetrate fire resistant barriers to maintain the effectiveness of the overall fire separation. While fire stopping applications are well accepted globally, current understanding of actual fire performance is very limited and relies on standard fire test outcomes and extrapolated engineering judgement, without much scrutiny. Above all, a dearth of available thermophysical properties of common firestop materials significantly restrains the development of reliable numerical solutions. The objective of this research is therefore to optimize pseudo thermophysical properties that can be applied to model the temperature response of a typical firestop acrylic sealant. The study adopted an inverse modelling approach. Through iterative adjustment of key thermophysical parameters, a preliminary optimization for a typical firestop acrylic sealant has been attained. The simulated in-depth temperature predictions demonstrate a reasonable consistency with corresponding thermocouple data collected through customized ignition apparatus experiments. The proposed analysis methodology provides an alternative line of thought to obtain the effective thermophysical properties for fire safety designs.

The role of a novel coating of SFRCR-ECC in enhancing the fire performance of CFST columns: Development, characteristic and ISO-834 standard fire test

The conventional spray-applied fire-resistive material meets the basic fire resistance requirements. However, it has limited strength and ductility, and poor bonding with the substrate, consequently, it will not deform with the main structure and reduces the fire resistance performance. A multifunctional spray-applied, fire-resistive and corrosion-resistive Engineered Cementitious Composites (SFRCR-ECC) has been developed to overcome these defects. Material properties of SFRCR-ECC coating were initially investigated, as well as the ISO-834 standard fire test of CFST columns sprayed with SFRCR-ECC coating were carried out. The effects of SFRCR-ECC coating thickness and the load ratio of the columns to the fire resistance limit were preliminarily explored, while the damage of the specimens after the open fire test, the temperature distribution and the axial deformation of CFST columns were obtained. The open fire test results also proved that SFRCR-ECC has excellent fire resistance performance as a new sprayable fire resistant material.

Wind loads tests of external walls blocks masonry of noncombustible polystyrene concrete

Introduction. Blocks of non-combustible polystyrene concrete of D300 density grade, B1 compressive strength class with normalized thermal conductivity λ0 = 0,078 W/(m·°C) and frost resistance grade not lower than F75, developed by LLC “Institute VNIIZhelezobeton”, were used in masonry with a thickness of 375 mm without special fireproof lining. Such masonry successfully passed standard fire tests for fire hazard and fire resistance, which showed the possibility of its use in external non-bearing energysaving walls of multi-storey buildings (up to 25 floors inclusive, about 75 m high).Aim. Evaluation of the strength and deformation characteristics of non-combustible wall masonry made of noncombustible polystyrene concrete blocks with a density of D300 at design wind loads at a height of about 75 m. Materials and methods. Fragments of uncoated wall masonry 375 mm thick, 2,7 m high and 1,2 m wide of noncombustible polystyrene concrete blocks mounted on a mortar with over-all dimensions of 295 × 375 × 595 mm were tested.The test procedure is in accordance with State Standard 8829-2018.Results. The destructive bending load exceeded the calculated one by an average of 4,1 times, while the deflection in the middle of the fragment was 1,9 times less than the permissible one.A methodology has been developed for calculating the strength and deformability of masonry of polystyrene concrete blocks under wind loads, taking into account the influence of horizontal and vertical masonry joints, which is scheduled to be reflected in Amendment No. 1 SP 434.1325800.2018.Conclusions. The results of wind load tests showed that for unlined masonry made of non-combustible polystyrene concrete blocks with a density of D300 and a thickness of 375 mm, the requirements for strength and deformability are met with a significant margin. The results of tests for wind and fire effects of the specified block masonry make it possible to use it in nonbearing external walls of multi-storey residential energyefficient buildings up to 75 m high in virtually all regions of Russia.