Terms Of Fire Resistance Research Articles

Solving Separation Distances from Flammable Surfaces of Exterior Walls by Central-European Standards

The paper deals with the topic of determining the density of heat flow from combustible surface treatments of exterior walls, such as combustible insulation systems, combustible cladding of facades and from all-wood constructions of exterior walls. Heat flow density is an important indicator in determining the fire resistance rating of exterior walls and in determining safe separation distances. The article describes the ways in which exterior walls can be classified in terms of fire resistance. One of these methods is a numerical calculation (of the surface amount of released heat and heat flow density), which will be applied to various types of combustible surfaces of the perimeter walls of wooden buildings. The results showed that the numerical calculation is a suitable method for determining the classification of fire resistance rating of exterior walls with combustible coating. The Czech legislation defines the criteria for this classification better.

Effectiveness of Flax-TRM composites under traction

The scientific research in the field of masonry structures is increasingly welcoming the adoption of innovative and sustainable rehabilitation techniques aimed at the safeguarding of the Built Cultural Heritage. Textile Reinforced Matrix (TRM) composites are the most widely investigated strengthening systems for ancient masonry structures, thanks to their high compatibility level with the material substrates in terms of fire resistance, chemical/physical aspects, reversibility property, little impact on dimensions, stiffness and weight. Nevertheless, in the last years, the growing concern on sustainability increased the interest in products with low environmental impact, for promoting circular economy approaches in the design of the structural interventions. In particular, efforts have been done to replace the most common composites with materials less harmful to the environment, such as natural fibres, for developing compatible and sustainable rehabilitation techniques for masonry structures. This paper presents the preliminary results of experimental tests conducted by the authors on specimens of TRM composites made with natural, vegetable, flax-fibre grids and natural hydraulic lime mortar. The mechanical characterization tests aimed at detecting the tensile behaviour of the natural TRM system compared to the results available in the literature on different vegetable-fibre composites and TRMs made with natural basalt fibres. The experimental tests highlighted the promising mechanical effectiveness of natural TRM systems under traction and offered a hint to further research aimed at improving their mechanical strength and stiffness.

Fire Retardancy of Cementitious Panels with Larch and Spruce Bark as Bio-Admixtures.

The aim of this study is to investigate the production of fire-resistant panels made out of bark from spruce (Picea abies), larch (Larix decidua Mill.) and cement. This research included test panels produced from bark, cement, water and cement-bonded recycling material aiming for the target density of 750 kg/m3. The physical (density, dimension stability, thickness swelling) and mechanical properties such as tensile strength and compressive strength together with fire resistance were tested. Considering the results, appealing values have been achieved: max. compressive strength: 3.42 N/mm2; max. thickness swelling: 5.48%; and density: 515 to 791 kg/m3. In principle, the properties of the produced panels depend not only on the density, but also on the hydration and, above all, on the compaction and the composition of the boards. The fire tests demonstrated that the produced panels have an enormous potential in terms of fire resistance and could be utilized for fire-retardant applications.

Investigation of Thermal Effects on Nailed Connection of Mass Ply Panels

Abstract Mass ply panels (MPP), a relatively new mass timber product, has been utilized in several construction projects as diaphragm and wall panels. Connection for MPP is a crucial structural component that requires a better understanding. This article presents an experimental investigation into elevated temperature exposure–driven property degradation of MPP nailed connections, which is important for both the design of new structures in terms of fire resistance and the rehabilitation of structures partially damaged by fire. One control group and 32 exposure groups, which were combinations of eight elevated temperatures and four exposure durations, were investigated. The failure modes and yield strength of the nailed connection were analyzed as a function of elevated temperature and exposure time and compared with the prediction from the National Design Specification and existing literature. The results show a decrease of up to 45 percent in initial stiffness and ultimate load; meanwhile, there was no statistical evidence for the change in yield load in the majority of testing groups. Two analytical models, namely, multilinear regression and first-order kinetics model, were proposed to model the degradation of initial stiffness and ultimate strength. The kinetics model provided a better prediction and suggested that the initial stiffness and ultimate strength of the nail connection degraded over time at rates depending on the exposure temperature.

Behavior of RC Beams Strengthened with NSM-CFRP Strips Subjected to Fire Exposure: A Numerical Study

The use of Near-Surface Mounted (NSM) Carbon-Fiber-Reinforced Polymer (CFRP) strips is an efficient technology for increasing flexural and shear strength or for repairing damaged Reinforced Concrete (RC) members. This strengthening method is a promising technology. However, the thin layer of concrete covering the NSM-CFRP strips is not adequate to resist heat effect when directly exposed to a fire or at a high temperature. There is clear evidence that the strength and stiffness of CFRPs severely deteriorate at high temperatures. Therefore, in terms of fire resistance, the NSM technique has a significant defect. Thus, it is very important to develop a set of efficient fire protection systems to overcome these disadvantages. This paper presents a numerical study that investigates the fire behavior of thermally insulated RC beams flexurally strengthened with NSM-CFRP strips and subjected to fire exposure according to the ISO 834 standard. The numerical study considered three-dimensional finite element models in the ABAQUS software that have been developed to simulate and predict the performance (thermal and structural response) of fire endurance tests on strengthened, uninsulated strengthened, and thermally insulated beams strengthened with NSM-CFRP strips, which were exposed to fire and had different fire insulation schemes. The insulation used was plaster from local material with a thickness range of 25 to 50mm. The variation of the thermal and mechanical properties with the temperature of the constituent materials was considered. All beams' mechanical and thermal responses were adequately simulated using numerical models. The results of the numerical simulations were in good agreement with the experimental data. The fire behavior of the NSM-CFRP strengthened RC beams was examined and particularly the efficiency of the NSM strengthening system during the fire. The behavior in the fire of the NSM-CFRP strengthening system on the RC beams thermally protected with different fire insulation schemes was assessed. Finally, the effectiveness of fire insulation was studied.

Research into the physical and chemical properties of fire-retardant materials of structural elements of trucks running on gas engine fuel with the aim of increasing their fire-retardant efficiency

The fire load is an integral part of the fire hazard definition. Reducing this load is one of directions to fight fires in transport. To study the physicochemical processes and thermal effects occurring as a result of thermal decomposition of wood fire-proofed by retardants like BAN, OK-GF, OK-DS (OK-GFM), SPAD-0 and their chemical compositions, we used the methods of differential thermal analysis, thermogravimetry, and derivative thermogravimetry. In addition, to study the intensity of physicochemical combustion processes, tests to control changes in woodwork masses and temperature at the top of pipe depending on the duration of combustion of the samples and the consumption of fire retardants were conducted. Fire retardant compositions like OK-GF, OK-DS, Pirilax biopyrene at the consumption of 0.1 kg / m2 ensure flame and combustion resistance of the wood. The analysis of the research results confirmed the possibility of assigning to wood structures of a lorry’s body of the group 1 of flame and combustion resistance. Using the above fire retardants and their compositions in the treatment of lodgment elements and runners significantly affects the possibility and duration of the combustion process of a lorry. This was tested by means of an artificial fire source method (without chemical treatment, the burning time does not exceed 50 minutes). This significantly improves post-collision safety of vehicles with an increased fire load in terms of fire resistance because of using the natural gas as a motor fuel.

Experimental and analytical investigation on fire resistance of glulam-concrete composite beams

The timber-concrete composite beam characterized by good mechanical behavior, low susceptibility to vibration and high sound insulation has a wide application in high-rise and long-span timber structures. However, the published study on the fire resistance of TCC beam is limited. In this research, one short-term failure test at ambient temperature and five full-scale fire tests were performed on the glulam-concrete composite beams. The influences of the load ratio, presence of timber board and fire-rated gypsum plasterboard on the temperature field and fire resistance were investigated in detail. The test results showed that the fire resistance of the composite beam was decreased with the increase of the load ratio. The composite beam with timber board interlayer outperformed the beam without the interlayer in terms of fire resistance. Moreover, the fire-rated gypsum plasterboard protection on the glulam beam could effectively improve the fire resistance of the composite beam. The finite element models of the composite beams were established to predict the temperature field of composite beams under fire. The average temperature values of concrete slabs under different fire times were obtained from numerical simulations. Considering the influence of high temperature on the glulam beam, concrete slab and shear connectors, the calculation methods of load carrying capacity and bending stiffness of the composite beam under fire were proposed.

Fire Resistance and Mechanical Properties of Intumescent Coating Using Novel BioAsh for Steel

Recent developments of intumescent fire-protective coatings used in steel buildings are important to ensure the structural integrity and safe evacuation of occupants during fire accidents. Flame-retardant intumescent coating applied to structural steel could delay the spread of fire and heat propagation across spaces and structures in minimizing fire risks. This research focuses on formulating a green intumescent coating utilized the BioAsh, a by-product derived from natural rubberwood (hardwood) biomass combustion as the natural substitute of mineral fillers in the intumescent coating. Fire resistance, chemical, physical and mechanical properties of all samples were examined via Bunsen burner, thermogravimetric analysis (TGA), carbolite furnace, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR), freeze–thaw cycle, static immersion and Instron pull-off adhesion test. Sample BioAsh intumescent coating (BAIC) 4-7 incorporated with 3.5 wt.% BioAsh exhibited the best performances in terms of fire resistance (112.5 °C for an hour under the Bunsen burner test), thermal stability (residual weight of 29.48 wt.% at 1000 °C in TGA test), adhesion strength (1.73 MPa under Instron pull-off adhesion test), water resistance (water absorption rate of 8.72%) and freeze–thaw durability (no crack, blister and color change) as compared to other samples. These results reveal that an appropriate amount of renewable BioAsh incorporated as natural mineral fillers into the intumescent coating could lead to better fire resistance and mechanical properties for the steel structures.

Feasibility and strength properties of the geopolymeric binder made of fly ash suspension

Geopolymeric binders, or in general geopolymers, are nowadays applied in many different branches of the industry –also in building construction. This relatively new group of inorganic materials has similar strength properties as ordinary Portland cement (OPC) and in some features, it is even better (for example in terms of fire resistance or chemical resistance). It is also environmentally friendly material because industrial or mining tailings are used as its main components and the production process is not so energy consuming as in case of OPC. Paper presents laboratory research focusing on the curing temperature impact on strength properties of geopolymeric binder made of fly ash suspension. Besides the suspension which is a waste product from coal power plant, also recycled ground glass and metakaolin were used as the additions. The chemical activator of geopolimerisation reaction was prepared with the use of sodium hydroxide and sodium silicate. Prism samples 40x40x160 mm were done and then the flexural and compressive strength tests were performed. The paper also presents the impact of covering the moulds during heat curing on condition of geopolymeric binder samples.

Impact of improper storage and installation of glazed fire rated walls on their performance

The article describes issues related to fire resistance of glazed elements. The influence of the method of storage, transport, seasoning, manufacturing defects, irregularities in the scope of fixing the glass and the thickness of the glass sheet on the effectiveness of the partition in terms of fire resistance is presented.

Effect of different weightage of Enova® IC3100 silica aerogel on aluminium alloy composites in ISO2685 aviation standard fire-test

The study presents the use of Enova® IC3100 and hardener/epoxy resin on the metal alloy and a hybrid composite of metal with natural fibre (flax) with the percentage of aerogel, for use in aircraft high-temperature region. The main objective of the study is to determine the percentage amount of Enova® IC3100 and epoxy resin/hardener on the hybrid composite. The composites were fabricated using different percentage of aerogel in an epoxy. The composites undergo a fire test using ISO2685 propane-air burner. The results obtained indicate that a less layered aluminium alloy coated with greener and lighter substance mix with epoxy resin/hardener can be used in a high-temperature aircraft application. The hybrid composite with flax fibre presents 5-10% greater than the other composite in terms of fire resistance. The study shows that the composite of aluminium alloy 2024-T3 coated with silica aerogel possesses good properties that resist high-temperature in an aircraft component.

PERFORMANCE OF SAWDUST CONCRETE AT ELEVATED TEMPERATURE

The aim of this study was to shows the behavior of sawdust concrete at elevated temperature. Sawdust is considered as waste material but nowadays this waste material is utilized in the construction of the building as sawdust concrete. Sawdust is a by-product of wood which is generally used in the production of lightweight concrete, possessing low thermal conductivity. In this study sawdust concrete was made at three different proportions of cement and sawdust 1:1, 1:2, 1:3 by volume. At these proportions, the physical and mechanical properties such as density, workability, strength, fire resistance, mass loss, ultrasonic pulse velocity and residual strength were investigated after 28 days of curing. It was found that with the increment in the amount of sawdust, the workability and strength decreases, however in terms of fire resistance, concrete with lower amount of sawdust performed well. Considering the overall physical and mechanical properties, sawdust concrete can be used in building construction.

Mechanical properties of concrete composites subject to elevated temperature

Fire resistance represents an important parameter which is necessary to consider during the structural design of buildings. It is defined as an ability of building components to perform their intended load-bearing functions under fire exposure. In terms of fire resistance, the right choice of a construction material plays a key role and can reduce structural damage or even save human lives. The building industry offers a wide range of materials whose structural behaviour is more or less affected by temperature. Recently, concrete has become one of the most utilized materials used for a various kind of buildings. While the knowledge and experience with concrete behaviour under ambient temperature are well-known, the behaviour under elevated temperature has to be deeply investigated.The paper deals with observing the behaviour of concrete composites with addition of fibres under ambient and elevated temperature with the aim to determine the mechanical properties of materials. The experimental tests were conducted on three selected concrete composites which differ in a type and content of fibrous reinforcement used. The experimental work carried out was divided into several phases. First of all it was necessary to leave the produced specimens aging and drying in order to minimize the risk of unexpected damage caused by concrete spalling during heating. Time to time, the specimens were weighted with the aim to determine the loss of weight imposed by drying. Then, a heat transport test was performed on a few reference specimens in order to determine the time required for uniform heating the specimens up to 200 °C, 400 °C and 600 °C. In the last phase, conventional testing methods were undertaken to determine the mechanical properties of concrete composites at ambient and elevated temperature. A compression test and a splitting tensile test were conducted on 150 mm cubes. Based on the results, the peak and residual strength of the materials were determined for various temperature levels. The obtained findings contribute to improving the knowledge in the field of both concrete structures exposed to high temperature and structural behaviour of fibre reinforced concrete. The findings can be also utilized in case of the structural design of concrete structures with the high risk of fire loading.

Use of waste glass in alkali activated cement mortar

This paper presents a study on alkali activated cement (AAC) mortar produced with waste soda-lime-silica glass. The waste glass was used simultaneously as a precursor and fine aggregates in the alkali activated fly ash-slag mortar. The influences of waste glass in cullet and powder forms on workability, compressive and flexural strengths, fire resistance of the AAC mortar were investigated. The experimental results showed that the workability was gradually increased as the replacement level of natural sand by glass cullet was increased, and it was significantly improved with decreasing aggregates-to-binder ratios. The mechanical properties data indicated that the compressive strength was reduced as the glass cullet content increased. However, for the flexural strength, the optimum percentage of glass cullet replacement was 50%. Due to the low reactivity, a reduction in strength was observed when the glass powder was used to replace the fly ash and slag. Nevertheless, in terms of fire resistance, the incorporation of glass cullet could improve the resistance of the AAC to high temperature exposures (800 °C). In particular, the AAC mortar prepared with the glass powder as a precursor exhibited remarkable resistance to high temperature. The use of waste glass in AAC material was feasible from the mechanical properties and fire resistance points of view.

Lightweight building envelopes in prefabricated buildings in terms of fire resistance

Dimensioning the lightweight, building envelopes in prefabricated buildings in terms of fire protection within the passive standard. Legislation. Optimizing the protection of a supporting system in prefabricated wood-based walls in terms of thermal and fire protection according to Eurocodes.

Modelling initial mortality of Abies religiosa in a crown fire in Mexico

Aim of study: The objectives of this work were to determine which morphological and fire severity variables may help explain the mortality of adult Abies religiosa (Kunth) Schltdl. & Cham., to model the probability of this species after being affected by crown fire, and to obtain more elements to classify the sacred fir in terms of fire resistance. This type of studies are relevant to estimate the impact of crown fires on the climax forests that forms this species.Area of study: The burned forest was located in the southern Mexico City, borough.Material and methods: Morphological variables and fire severity indicators were collected for 335 Abies religiosa trees burned by a mixed severity fire. Logistic regression was used to analyze data and develop models that best explained tree mortality.Main results: Survival was 26.9%. The models for height (p≤0.0001), diameter at breast height (p=0.0082), crown length (p≤0.0001) and crown base height (p≤0.0001) were significant, with a negative relationship between each one of these variables and probability of mortality. The significant severity variables were lethal scorch height (p≤0.0001) and crown kill (p≤ 0.0001), which have a direct relationship with probability of mortality.Highlights: This species is moderately fire-resistant. Crown kill ≥ 70% markedly increases mortality. Silvicultural activities such as pruning, thinning and fuel management can reduce the risk of crown fires.

강섬유 콘크리트 혼입율에 따른 내부앵커형 콘크리트 충전기둥 내화성능에 관한 해석적 연구

Professor, Department of Architectural Engineering, University of Seoul, Seoul, 02504, KoreaAbstract - Concrete filled steel tube system has two major advantages. First, the confinement effect of steel tube improves the compressive strength of concrete. Second, the load capacity and deformation capacity of members are improved because concrete restrains local buckling of steel tube. It does, however, involve workability problem of using stud bolts or anchor bolts to provide composite effect for larger cross-sections. While the ribs inside the columns are desirable in terms of compressive behavior, they cause the deterioration in load capacity upon in-plane deformation resulting from thermal deformation. Since the ribs are directly connected with the concrete, the deformation of the ribs accelerates concrete cracking. Thus, it is required to improve the toughness of the concrete to resist the deformation of the ribs. Welding built-up tubular square columns can secure safety in terms of fire resistance if the problem are solved. This study focuses on mixing steel fiber in the concrete to impro ve the ductility and toughness of the columns. In order to evaluate fire resistance performance, loaded heating test was conducted wit h 8 specimens. The behavior and thermal deformation capacity of the specimens were analyzed for major variables including load ratio. The reliability of heat transfer and thermal stress analysis model was verified through the comparison of the results between the test and previous study.Keywords - Fire resistance, Composite column, Steel-fiber, Heat transfer, Thermal stressNote.-Discussion open until August 31, 2016. This manuscript for this paper was submitted for review and possible publication on June 22, 2015; revised December 22, 2015; approved on January 13, 2016.Copyright ⓒ 2016 by Korean Society of Steel Construction

Fire Resistance Study of Concrete in the Application of Tunnel-like Structures

For submerged floating tunnels and other underwater structures with a confine space, fire is an unavoidable and critical issue. In the existing designs, concrete has been widely employed to increase the strength or function as ballast to stabilize the structures due to hydrodynamic loadings, such as wave and current. Nevertheless, it is noteworthy that concrete owns its merits to protect structures from fire, even though there are still a number of technical and scientific problems to tackle. In this paper, the mechanical behaviour of concrete is studied under high temperature in fire. Later, numerical simulations are performed so as to attain quantitative results in applications of tunnel-like structures. Particularly, some structural parameters are investigated in terms of fire resistance, i.e., compressive strength of concrete, yield strength of steel and the length of SFT. The effects of these parameters on the fire resistance time of SFT that were exposed to an RABT fire curve are discussed to illustrate the importance to optimize the values within a reasonable range.

Consumer Attitudes Towards Timber Frame Houses in China

Timber framed architecture owns thousands of years’ history in China. However, with the rapid industrialization and urbanization, timber frame houses have substantially deceased. In order to reduce the concentration of the greenhouses gas CO2 in the atmosphere and establish a low carbon society, the promotion of green building materials and energy saving buildings has been put in a prominent place by Chinese government. However, both of the number of timber frame houses and the potential of using timber, the green and sustainable architectural materials, are still very low in China. This paper presents findings from a questionnaire, shows the Chinese consumers’ attitudes to timber frame houses. The semi-structured questionnaire method was chosen to explore common consumers’ attitudes. It is found that prejudice regarding the deficiency of timber houses, in terms of fire resistance, durability and stability, persists in the minds of consumers. The aim of this paper is better understanding the challenges and difficulties that timber frame houses market facing from the view of consumers, thus figure out better ways for the future development.

Study of the mechanical performance of Grade 1860 steel wires at elevated temperatures

The mechanical performance of pre-stressed steel wires at elevated temperatures is a key and fundamental topic for the study of pre-stressed steels in terms of fire resistance and evaluation of post-fire structural damages. In this article, tension tests of grade 1860 ФP5 high-strength steel wires at elevated temperatures and post-treatment tension tests of high-strength steel wires were reported. The results revealed that the stress–strain curves of the high-strength steel wire samples at elevated temperature were relatively smooth, while the mechanical performance degraded as the temperature increased. Meanwhile, the mechanical performance of post-treatment sample showed insignificant variation at temperatures lower than 300°C but significantly degradation at temperatures higher than 300°C. This study serves as an essential reference to future studies of pre-stressed steels.