Fire Resistance Limit Research Articles

Fire resistance of lightweight steel-concrete slab panels under high-temperature exposure

Lightweight steel concrete structures (LSCS) - an innovative energy-efficient building structure type that can be used both as load-bearing and as enclosing one. They consist of profiled steel - usually galvanized and cold-bent - filled with a monolithic foam concrete with a 400kg/m3 density and with fiber cement sheets sheathing. These structures can be used in industrial and civil buildings as internal and external bearing and enclosing wall structures and as slabs, energy-efficient roof covering. According to the LSCS production method, prefabricated panels (walls and slabs) and building site performed constructions are distinguished. The paper presents the testing results with the aim to determine the fire resistance limit of a slab panel fragment by bearing capacity (R), loss of integrity (E), loss of heat insulating capability (I) and fire hazard class. Two samples of a slab panel fragment were selected for the fire resistance high-temperature tests. The actual fire resistance limit of samples of the slab panel fragment is at least REI 60 with a uniformly distributed load 4 kN/m2.

Method of engineering calculation of the fire resistance limit for load-bearing metal structures

Method of engineering calculation of the fire resistance limit for load-bearing metal structures

Some Approaches to Developing a Test Method for Determining the Actual Fire Resistance Limit of Façade Translucent Structures

Based on the analysis of modern construction of high-rise buildings with façade translucent structures (FTS), it was established that the actual fire resistance limit of FTS for high-rise buildings should be assessed. The criterion for loss of fire resistance of a translucent façade is the collapse or fall-out of fragments of the translucent façade filling that contribute to the spread of fire in the building. By analyzing the experience of tests carried out fragments of buildings with FTS with simulated thermal and/or fire (flame torch) effects, the following factors are taken into account: wind loads with variable directions of air flows; access of fire-fighting and rescue units, etc. During full-scale FTS tests, a possible scenario of fire development is simulated, taking into account the fragment and features of the specimen, the fire load that affects the development of fire along the façade, the structural design of the FTS, – glass (conventional and fireresistant) and structural elements. The authors suggest that in order to ensure fire safety of high-rise buildings with FTS the fire-resistance limit assessment should be carried out on fragments of buildings with a simulation of thermal and/or fire impact, which is close to the real conditions.

Optimization of technology of special-purpose mineral wool products

Insulation systems must have a number of special properties when used on construction sites located in the zone of significant negative temperatures, wind load, and associated air filtration through building struc-tures, under the influence of the coastal environment that forms salts on tech-nical facilities associated with the production and transportation of petro-leum products. Firstly, high operational stability, including under the influ-ence of aggressive environments. Secondly, they must be non-flammable and have significant fire resistance limits. Thirdly, do not contain compo-nents that are toxic during normal operation or are released in the event of a fire. The analysis of possibilities has shown that products based on stone wool meet these requirements to the greatest extent as a thermal insulation material. The research presented in the article is based on a hypothesis about the use of products based on stone wool and epoxy binder on latent hardeners, which will allow us to obtain an energy-efficient material that fully meets the conditions of polar construction. The purpose of the research was to develop a method for selecting the parameters of manufacturing mineral wool products that affect the properties of mineral wool slabs to the greatest extent and to opti-mize the temperature of heat treatment of mineral wool carpet. Re-search methodology set out in the article is based on the method of mathematical planning of experiment and statistical processing of the results, followed by analytical optimization.

Research of Integrity of Fire Insulation Cladding with Mineral Wool of Steel Beam under Fire Impact

In the article, the processes of integrity loss of fire-retardant cladding from mineral wool of a steel I-beam are considered. The relation between fire-retardant cladding integrity and its thermal insulating ability was studied. Computer model of a steel beam with fire-retardant cladding of mineral wool, which takes into account its own weight, current mechanical load and temperature mode of heating under the heat-insulating effect of the cladding, using the computer system LS-DINA, is developed in this article. It is shown that the fire-retardant cladding loses its integrity under the thermal influence of fire long before the onset of the limit state of loss of fire resistance in terms of bearing capacity. The conditions under which fire-retardant cladding loses its integrity and fire-retardant ability are investigated. Having considered the time of fire-retardant cladding integrity loss the fire resistance limit can be significantly clarified and allows to avoid early collapse of building structures cause by fire.

Numerical Analysis of Ultimate Mechanical Characteristics of Suspension Bridges’s Cable in High Temperature Fire

Relying on the joint research project, research is carried out on the ultimate mechanical characteristics of suspension bridge slings under high temperature fire. The establishment of a local transient temperature field heat transfer model based on the FDS software, and the analysis of the temperature distribution law of the fire source at different wind speeds. The most unfavorable fire condition is the combination of the fire source heat release rate of 300MW and the wind speed of 14m/s; the overall structure model of the bridge is modeled by ANSYS software. Firstly, the modal analysis of the whole bridge model is carried out to verify the accuracy of the modeling, and then the thermal structural coupling analysis is carried out under the most unfavorable fire conditions to obtain the structural response of the whole bridge structure under the sling fire. According to the change trend of the structure response of the cable under fire, the fire resistance limit of the bridge structure is obtained as 460°C; Under the most unfavorable fire burning situation, when the limit number of broken cable in the span is 3, the cable will be caused into collapsing continuously; the composite protective layer has a significant effect on the fire resistance of the cable.

INVESTIGATION AND MANAGEMENT OF FIRE RISKS AT SITES WITH APPLICATION OF TRANSLUCENT BUILDING STRUCTURES

On the base of analyses on the development of the construction industry as well as fires occurring in Kazakhstan, the article justifies the areas of fire prevention related to technical regulation that is the certification of materials, construction structures and engineering systems. The translucent building structures have increasing application in modern construction techniques. For such structures, the most vulnerable indicator is the fire resistance limit. A technical solution is offered to increase this indicator by using water irrigation. On the base of existing international and national regulatory documents, a number of methods has been developed for experimental determination of the actual fire resistance limit by cooling of structures with water in case of fire. Large-scaled fire researches have been carried out to determine the actual limit of fire resistance of the translucent partition made of tempered glass "Float" with the thickness of 12 mm, M1 grade both in the presence of water irrigation and in the absence thereof. The tests were carried out under standard and actual fire conditions. Optimal parameters of water irrigation are determined. On the base of research results, it is proposed to improve the construction standards in this field as well as methodological documents in the field of certification tests.

Оценка огнезащитной эффективности покрытий для стальных конструкций

Представлены результаты анализа экспериментальной и аналитической оценки огнезащитной эффективности покрытий для стальных конструкций. Обобщены данные многолетних исследований по определению зависимостей от температуры таких теплофизических характеристик, как теплопроводность и теплоемкость. Разработана структурно-методологическая схема выбора огнезащитных покрытий для стальных конструкций в целях обеспечения нормативных требований по огнестойкости. Проведены экспериментальные исследования по определению огнезащитной эффективности терморасширяющихся покрытий на эпоксидной основе при воздействии температурного режима горения углеводородов. Рассмотрен вопрос о гармонизации методики экспериментальной оценки огнезащитной эффективности средств огнезащиты для стальных конструкций с действующими европейскими нормами. Установлены критерии выбора пассивной огнезащиты, зависящие от области применения способов огнезащиты. Steel structures have high strength, relative lightness and durability, but when exposed to high temperatures in a fire, they deform, lose stability and load-bearing capacity. The collapse of load-bearing steel structures can occur in 10-15 minutes after the fire start. The actual fire resistance limit of structures can be increased by using the active and passive fire protection systems. The use of the active system for increasing the actual fire resistance limit is not provided in the regulatory documents. Passive fire protection is a complex of technical solutions including the use of non-flammable materials and bulging compounds. It is also an integral part of the building structure that ensures the required fire resistance limit. Assessment of fire resistance of building structures of residential, public, warehouse and industrial buildings is carried out taking into account the temperature regime (cellulose) of a standard fire. At oil and gas, petrochemical enterprises as well as at oil production platforms fires can occur at combustion of various hydrocarbon fuels which are characterized by a rapid temperature increase to 1100 °C. In this case, in accordance with GOST R EN 1363-2-2014, the temperature regime of hydrocarbon combustion is used to assess the fire resistance of building structures. The fire-retardant effectiveness of fire protection means for steel structures is determined by the heating time of the standard I-shaped column without applying a static load on the sample to the average “critical” temperature of the steel of 500 °C. Materials used for fire protection of steel structures must have a good thermal insulation ability, which is estimated by the coefficient of thermal conductivity. When heated to high temperatures, the thermal conductivity coefficient of fire-resistant materials varies depending on their composition and temperature. Based on the analysis of research to determine the fire-retardant effectiveness of fire protection means for steel structures there was developed a structural and methodological scheme that allows to make a choice of fire protection. Currently, as a fire protection there are widely used intumescent paints and thermo-expandable coatings. Taking into account the lack of knowledge of the influence of long-term operation and a large number of other technological factors on the fire-retardant effectiveness of coatings of steel structures covered with intumescent paints, it would be right to limit the use of such type of fire protection for load-bearing structures contributing to the overall sustainability of buildings with a required fire resistance of R 30. For fire protection of steel structures of oil and gas facilities located in the open air, in severe climatic conditions and exposed to aggressive environments there is successfully used a thermo-expandable two-component epoxy-based coating. The analysis of experimental data showed that the use of epoxy-based coatings is suitable for metal structures in the open air. In closed rooms the epoxy intumescent coating should not be used because at high temperature in a fire it ignites with toxic combustion products release.

Using scanning electron microscopy, x-ray diffraction and IR spectroscopy to study the ageing of intumescent fire-proof coatings

Introduction. The fire protection of metal structures is a relevant present-day problem; its solution implies better fire resistance performance of structures attainable through the application of intumescent fire-proof coatings whose service life expectancy is limited.Goals and objectives. Comprehensive studies of domestically made coating samples were performed to analyze the changes in the chemical composition of intumescent coatings containing ammonium polyphosphate, melamine, and pentaerythritol. The samples were exposed to artificial climatic ageing (3, 6, and 9 years). Methods. Optical and scanning electron microscopies were used to study the appearance of samples, the morphology of inclusions and the surface microstructure. X-ray diffraction and IR spectroscopy were employed to study the phase and structural states of samples, and the swelling ratio of fire-proof coatings was also examined.Results and discussion. It’s been found out that the swelling ratio of samples goes down to a significant extent as the time progresses, and when the residual life of a coating reaches 30 %, the fire resistance limit of the structure goes down. Sample ageing is the reason for gradual phase composition changes due to the melamine content reduction by 40 %, ammonium polyphosphate content reduction by 15 % and redistribution of other components that change the microstructure of coatings, as well as their fire retarding properties.Conclusions. The changes, influencing the ability of a coating to maintain its fire retarding efficiency as declared by the manufacturer, take place in the course of operation of a coating exposed to external factors. The regularities, identified by virtue of this research, can be used to study the samples taken at fire-proofed facilities to identify deviations from the initial condition of a coating and to forecast its actual service life.

Fire safety in Ukraine

Problem statement. The growing level of technical equipment of enterprises, the complexity of production processes are accompanied by increased energy intensity of production, high concentration of capacity and materials, the use of polymeric synthetic materials, increasing the area and number of storeys of industrial buildings. Under such conditions, non-compliance with fire safety requirements leads to significant economic losses and human casualties. The problem of fire safety in the operation of buildings and structures fully depends on fire-technical structures. As the statistical analysis shows in Ukraine, more than 90 % of fires occur in buildings and structures, therefore, determining the main causes of fires in buildings and structures is the main urgent task. The purpose of the article.To conduct the analysis of statistical data in relation to fires which arise in Ukraine. To define principal сauses of fires and basic directions of providing safety of buildings and buildings. Conclusions. The conducted analysis showed that considerable part of fires with considerable financial losses and death of people that take place in buildings. Therefore one of the basic tasks of providing safety of buildings is an increase in fire-resistance limit of building constructions and decline of combustibility of building materials. To prevent and successfully fight fires, it is necessary to know the physicochemical and flammable properties of substances and materials used, to be able to assess the fire hazard of substances and processes, to choose the right effective means of prevention and protection against fires and explosions.

Improvement of the Assessment Method for Fire Resistance of Steel Structures in the Temperature Regime of Fire under Realistic Conditions

There was researched the influence of fire temperature regimes, obtained by the proposed mathematical models, on the mechanical characteristics of metal structures. As a result, the identified patterns of the influence of the parameters of the premises with fires are shown as the slit coefficient decreases and the fire load density increases, the actual limit of fire resistance begins to decrease, as well as at values of fire load density less than 600 [MJ/m2], there is an area where the occurrence of a boundary state is not observed and Nomograms for determining the limit of fire resistance for steel structures at standard values of critical temperature were constructed and an appropriate method was developed.

Influence of the Fire Temperature Regime on the Fire-Retardant Ability of Reinforced-Concrete Floors Coating

In the paper, the tests have been analysed for fire-resistant quality of the hollow-core reinforced-concrete floors with fire-retardant plaster covering under standard temperature regime of the fire. Using the methodology for determining the characteristics of fire-retardant coatings ability for reinforced-concrete floors, the dependences have been obtained of the fire-retardant coating thickness from the concrete protective layer of a hollow-core reinforced-concrete floor for a fire resistance limit of 180 minutes with a temperature regime of hydrocarbon fire and a tunnel curve according to the Netherlands standards (RWS). It has been concluded about the minimum required thickness of the studied fire-retardant coating to provide the required fire resistance limit of a hollow-core reinforced-concrete floor under the indicated fire regimes.

Investigation of fire resistance of steel structures covering a warehouse building under different temperature conditions

Introduction . In the process of designing warehouse buildings, taking into account the adopted design decisions, it is required to assess the compliance of the actual fire resistance limits of building structures with the required fire resistance limits. The fire resistance limits of the (actual) building structures are determined under the influence of a “standard” temperature regime, the use of which can lead to both laying an overestimated fire resistance margin in a project and underestimating the thermal effect in a “real” fire. Aims and purposes . The purpose of the study is to assess the convergence of the “standard” temperature regime and possible “real” temperature regimes of fires in modern warehouse buildings, as well as the correspondence of actual fire resistance limits to the effects of “real” fires. To achieve this goal, the following tasks were solved: mathematical modeling of the development of a “real” fire by the field method in a warehouse building at different fire loads was carried out, as well as modeling of heating of the supporting structures of the coating according to the standard temperature regime and the “real” temperature conditions of the fire obtained during the simulation; the required fire resistance limits of the bearing building structures of the coating are determined through the equivalent duration of the fire. Methods . A storage building of a standard form with dimensions of 12×12×6.5 m was chosen as the object of the study. The building has a 4×4 meter gate in the amount of 2 pieces and an entrance door of 1×2 meter size. Within the walls of the building are 32 windows measuring 0.7×1 meter. Coverage — an impassable flat roof over metal trusses. The parameters of the fire load during mathematical modeling were taken according to the reference data of Yu.A. Koshmarov 12 types of typical fire load stored in warehouse buildings are considered. For mathematical modeling of “real” temperature fires, the “Fire Dynamics Simulator” (FDS) software package was used, which implements a field (differential) mathematical model. For mathematical modeling of the heating process of steel building structures, the finite-difference method for solving the Fourier heat equation with external and internal nonlinearity was used, implemented in the ANSYS Mechanical software package. results and discussion. The results of modeling in the FDS software package show that the temperature impact on the structure according to the standard temperature regime for fire loads: cables+wires, industrial oil, ethyl alcohol was less, which indicates an underestimation of the thermal impact on the structure. The results of modeling the heating of structures showed that the heating time of the coating truss is up to 400–700 °C for fire loads: cables+wires, industrial oil, ethyl alcohol less than the time obtained from standard tests, which indicates an initial underestimation of the actual fire resistance of steel structures of the coating when designing warehouse buildings. Conclusions . The assumption that the thermal impact of the standard temperature regime on the steel structures of modern warehouse complexes was underestimated was confirmed for 3 of the 12 fire loads considered, namely: cables+wires, industrial oil, ethyl alcohol.

Overview of software designated for the analysis of fire resistance of building structures exposed to various fire models

Introduction. When analyzing the fire safety of a facility, the conformity of actual limits of fire resistance of structures to the requirements of statutory documents is checked. Due to the complexity of the equations describing real systems and an extensive number of iterations required to obtain accurate results, software is used to perform calculations. One of the main goals of the paper is to analyze the software designated for the analysis of the fire resistance of building structures in case of different fire models. The paper presents an analysis of the criteria for the evaluation of software programs and their classification, evaluation of recommendations for choosing fire safety software in compliance with the specific requirements of users.Main (analytical) part. The paper analyzes various models of fires, taking into account the stages of fire spread, thermal and mechanical effects on structures exposed to fire, and prerequisites for their use by the software designated for the analysis of the fire resistance of building structures. Fire resistance models of structures, zone and field models, as well as models used to calculate evacuation time and detector response time when solving related problems are considered. The classification of software programmes is analyzed subject to the type of problems to be solved: the behavior of a structure exposed to high temperatures and mechanical impacts in case of real fire, and requirements applicable to safe structures. Certain estimates and assumptions, necessary for specialists to use software in their calculations, are considered.Conclusions. Recommendations on the choice of fire safety assurance software, meeting the specific needs of users, are provided.

Study on fire resistance of prefabricated concrete beam-column joint with end-plates

Purpose The purpose of this study is to put forward a high-strength bolt end-plate connection of prefabricated concrete beam-column joint and carry out the pseudo-static test. Design/methodology/approach ABAQUS finite element software is used to study the fire resistance performance of high-strength bolt end-plate prefabricated joint. This mainly considers the influence of axial compression ratio, screw preload, end-plate thickness and steel hoop thickness. Findings The results show that the thickness of end-plate and steel hoop has a certain effect on the fire resistance. The change of screw preload has little effect on the fire resistance limit. Compared with the cast-in-place concrete beam-column joint, the deformation trend of column-beam end of the fabricated joint is basically the same as that of cast-in-place joint. Originality/value To study the mechanical performance of this kind of joint more comprehensively, the finite element software is used to study the prefabricated concrete beam-column joint with end-plates, and the effects of axial compression ratio, screw preload, end-plate thickness and steel hoop thickness on the fire resistance of joints are mainly considered.

Features of modelling reinforced concrete structures in order to give fire resistance

The work explores the problem of assessing the limits of fire resistance of modern construction structures. Existing experimental methods are a fairly accurate way of assessing and are used in the certification of construction structures. Nevertheless, a significant problem in the development of new construction structures arises the problem of the need to conduct a large number of complex and expensive tests. Calculated evaluation methods are a reasonable alternative for pre-evaluating the effectiveness of the solutions developed. However, at present such calculations do not take into account the different types of design solutions and properties of new building materials. The work provides the results of experimental and calculated methods of assessing the limits of fire resistance. The analysis of the calculation results showed that when using regulatory documents in calculating the actual limit of fire resistance, the results differ by a maximum of close to 20 minutes. Thus, it can be concluded that the data obtained by the standards may produce inflated results. Currently, there are quite a lot of software products capable of solving such problems at a high level. One of the most powerful software complexes is ANSYS. This product allows you to construct a mathematical model of the object to conduct complex engineering calculations to determine the likely failure scenarios and parameters of control of the tensely deformed state of construction structures Object. A simulation of the behavior of a reinforced concrete slab during a fire, with the help of the ANSYS program, is shown.

Результаты натурных огневых испытаний центрифугированных железобетонных колонн кольцевого сечения

Цель. Оценить огнестойкость и поведение под совместной температурно-силовой нагрузкой центрифугированных железобетонных колонн кольцевого сечения путем проведения натурных экспериментальных исследований.
 Методы. Проведение натурных огневых испытаний колонн в составе фрагмента каркасного здания. Визуальное наблюдение за поведением колонн в процессе испытаний. Измерение температур огневой газовой среды, арматуры, бетона на внутренней поверхности колонн, в том числе в месте узла соединения с монолитным перекрытием. Измерение температуры и избыточного давления газовой среды в полости колонн.
 Результаты. Получены экспериментальные зависимости изменения температур арматуры, бетона на внутренней поверхности колонн, в том числе в месте узла соединения с монолитным перекрытием. Получен характер изменения температуры и избыточного давления в полости колонн. Выявлено, что стенки центрифугированных железобетонных колонн со свободной воздушной полостью имеют более высокую скорость прогрева, чем стенки с монолитной шпонкой в полости. Существенное влияние нарастающего давления газовой среды в полости колонн на их несущую способность не зафиксировано. Взрывообразное разрушение бетона колонн в ходе испытаний не зафиксировано. Разрушение одной из колонн в процессе огневых испытаний произошло в средней части высоты после образования магистральных трещин, направленных под углом 75–80º к продольной оси конструкции, и нарастание деформаций изгиба. Фактический предел огнестойкости опытных центрифугированных железобетонных колонн кольцевого сечения при внецентренно приложенной нагрузке в 18,25 т составил R60.
 Область применения исследований. Результаты исследования могут быть использованы при определении теплофизических характеристик центрифугированного бетона и разработке расчетной модели огнестойкости центрифугированных железобетонных колонн кольцевого сечения.

Model Analysis for Identifying the Load-Bearing Capacity and Fire Resistance of the Reinforced Concrete Column

In this paper a new technical solution in construction industry is presented, that relates in particular to testing compressed reinforced concrete elements - the building’s columns - for strength, stability and fire resistance, using scaled models. The subject matter is increasing the informative value, visual clarity and depth of experimental research of columns, using an economical technique of designing the geometric and force similarity of the reinforced concrete column’s scaled model for analyzing load-bearing capacity: strength, stability and fire resistance. The technical result is to identify the reinforced concrete column’s actual operation and its stress state from the beginning of the test and up to the stage of destruction; to evaluate the reinforced concrete column’s limit state according to its load-bearing capacity and fire resistance; to develop the analytical model for calculating the actual fire resistance limit; to save the labor costs for manufacturing the scaled test model of the real structure.

An evaluation of an actual fire resistance limit of non-protected steel structures for different temperature regimes of fires

Introduction . A normative document Set of Rules 2.13130.2012 (item 5.4.3) states that if an required fire resistance limit of structures is equal to R15 (RE15, REI15) an application of non-protected steel structures is possible. But an actual fire resistance limit depends both on a reduced thickness of the structure and a temperature regime of a fire (for example “cellulose” or hydrocarbon regime). This study is aimed on a numerical evaluation of the actual fire resistance limit of the non-protected steel structures for the standard “cellulose” and hydrocarbon temperature regimes of fires at various reduced thickness of the structures. Methodology and results . A numerical modeling of a heating of the structures was carried out using the software FDS 6. The non-protected steel structures having the reduced thickness δ cr from 3 to 60 mm were considered. The fire resistance limits were determined as a time interval from a beginning of the fire to the time moment when the temperature of the structure reaches a value of 500 °C. Dependences of the actual fire resistance limits on δ cr were obtained. These limits for the hydrocarbon fire were substantially lower than for “cellulose” one. A dependence of a ratio of the fire resistance limits for the hydrocarbon and “cellulose” fires on the reduced thickness of the structure was found. Conclusion . The results of this study confirm the requirement of the normative document Set of Rules 2.13130.2012 (item 5.4.3) concerning a possibility of the application of the non-protected steel structures in the case when the required fire resistance limit is equal to R15 (RE15, REI15), but only for the “cellulose” fire. But this requirement is not valid for the hydrocarbon fire.

Study on fire safety of cargo vehicles running on gas motor fuels

An innovative option for the development of the transport system of the Russian Federation is suggested, which provides for the establishment of an effective competitive transport system, based on the creation of high-performance safe vehicles and transport infrastructure. The presented characteristics of the age structure of the Russian fleet of vehicles indicate that they lag behind the current requirements for passive, active, post-accident, and environmental safety. In modern production and motor transport processes, new technologies are usually more fire-hazardous. One of the main indicators of passive fire safety is fire load, which determines the fire resistance limit of the structure and the requirements for fire protection systems. A block diagram for the fire hazard of cargo vehicles running on gas motor fuels is developed, which is based on fire load in cargo vehicles of category N2 running on compressed natural gas. The total thermal stress of the structure of cargo vehicles running on compressed natural gas is higher than that of gasoline and diesel vehicles by 5.6%. Full-scale tests of cargo vehicles running on gas motor fuels, using the method of creating an artificial fire seat, made it possible to solve issues of ensuring fire and explosion safety of vehicles by installing a bursting diaphragm on each high-pressure cylinder and using high-pressure cylinders made of alloy steel.