Purpose. To study project solutions aimed at improving a comprehensive approach to ensuring fire safety of transformer substations. Methods. The authors used methods of analysis and synthesis, summarization of materials of scientific works, regulatory documentation, project and technical documentation, probability theory, decision-making theory. Results. Design work is an important component of the process of designing and building transformer substations taking into account fire safety requirements. Design solutions for the enclosing fire protection structure must include the following sections: 1. Architectural and construction part. 2. Ventilation.3. Power supply and electric lighting. 4. Fire alarm. 5. Automation. The complex of transformer substations, surrounded by fire barriers, taking into account the described project solutions, is transformed from a static construction into a dynamic electrified structure controlled by logical devices. The devices respond to the state of the object’s technological parameters. The design and manufacture of fire barriers should consider analysis of potential threats and risks of fire, fire resistance of the material, design, compliance with safety standards and regulations. A comprehensive approach to ensuring fire safety of transformer substations has been improved. Solutions for the design of fire barriers take into account not only protection against the spread of fire, but also fire detection in the initial stages, as well as ensuring the safe course of technological processes of the facility. Scientific novelty. The authors improved the design solutions for creating a fire barrier when fencing open transformer substations of the enterprise, which consists in the use of an integrated approach, which includes, in addition to construction solutions, the use of modern automation and measuring equipment. The project features ventilation openings, axial exhaust fans with electric fire valves, smoke sensors, temperature and optical flame sensors, lighting devices, relay logic control modules. Practical significance. The proposed project solutions will help prevent the spread of fire in transformer substations, facilitate early fire detection, and ensure the safety of technological processes at the facility. Keywords: transformer substation, fire safety, fire barriers, security, project solutions.

The object of this study is the fire resistance of reinforced concrete hollow slabs at the onset of the limit state of loss of integrity. The problem of accurate modeling of the formation and development of cracks in concrete was investigated. The paper reports an analysis of the results of the stress-strain state of a reinforced concrete hollow slab during fire exposure for devising a method for evaluating the fire resistance of such structures upon the onset of the limit state of loss of integrity. According to EN 1992-1-2, the determination of fire resistance of structures is provided by calculation methods, however, there is no such procedure for reinforced concrete hollow slabs. Many scientific works offer refined methods for evaluating only the loss of load-bearing and heat-insulating capabilities, leaving aside the issue of loss of integrity. Thus, this can lead to a biased evaluation of reinforced concrete hollow floor slabs according to the criterion of the limit state of loss of integrity, which in turn can put under a threat to the fire safety of buildings, which threatens the life and health of people. According to the results of the calculation, a parameter has been determined, according to which the onset of the limit state of fire resistance, in particular, the loss of integrity, was established. Summarizing the damage distributions, it was assumed that in the case of reaching the critical plastic deformation of 2.5e-3 in concrete finite elements, they are excluded from the general set of finite elements. Thus, in the case of the formation of through cracks, the removal of finite elements is taken as a parameter to identify the onset of the limit state of loss of integrity. According to the results of the computational experiment, it was established that through cracks in a fragment of a reinforced concrete hollow slab are formed in 44 min. According to the results of the research, the method of evaluating the fire resistance of such structures based on the onset of the limit state of loss of integrity has been substantiated. Such a method could be applied during design, which provides an opportunity to determine the limit of fire resistance in reinforced concrete hollow slabs

The paper developed a computer model of the thermal and stress-strain state of a three-story car parking building, which consists of fire-resistant structures, taking into account: thermophysical characteristics of fire-resistant coatings, thermophysical and mechanical properties of the materials that make up the structure, nonlinear laws of deformation of the model materials, mechanical properties of materials at high temperature and force. Modeling of non-stationary heating of a reinforced concrete parking column with a square cross-section, dimensions 0.5×0.5×3 m under the conditions of exposure to a standard fire for 150 minutes was carried out. At the same time, it was found that the temperature on the reinforcing rods reaches 853 °C, which is sufficient to ensure the fire resistance of R150 at the given calculated forces in the column, and the mosaic of movements along the Z axis was not significant and amounted to 1.1 mm. The maximum reinforcement area was 5.55 cm2. When ensuring R180 fire resistance at the given calculated forces in the column, the temperature at the corner reinforcing bars reached 914 °С and the program calculated additional reinforcement. This indicates that the existing reinforcement is not enough to ensure the fire resistance of R180 at the given design forces in the column, so the maximum area of the reinforcement as a result of the calculation by the program increased to 58.7 cm2 (10 times more than the initial one). Measures to increase the fire resistance limits of structures, consisting in the use of fire-resistant coatings with scientifically based parameters, are proposed. The thickness of the passive fire-resistant coating, the coefficient of thermal conductivity, the specific heat capacity, which must be ensured when evaluating the fire resistance of a fire-resistant reinforced concrete column and increasing the limits of fire resistance to 180 minutes, are substantiated. Numerical calculations of non-stationary heating of a fire-protected reinforced concrete column of a parking lot (coating thickness 11 mm) under the conditions of exposure to a standard fire for 180 minutes revealed that the temperature on the reinforcing rods reached 213 °C, which is 4 times less than the heating of an unprotected column. Keywords: fire resistance, fire-resistant reinforced concrete structures, fire-resistant coating, thermophysical characteristics.

A finite-element model for the heat engineering calculation of fireproof reinforced concrete slab has been built, which is designed to assess the fire resistance of unprotected reinforced concrete structures. A feature of the model is the correct choice of types of heat transfer in the cavities of reinforced concrete ceilings. An algorithm that includes experimental and calculation procedures in determining the fire resistance of unprotected reinforced concrete structures has been applied. The initial, boundary conditions for the construction of the model were formulated; the thermophysical properties of materials were substantiated. Thermal calculation of fireproof multi-hollow reinforced concrete ceiling under conditions of fire was carried out. The adequacy of the developed finite-element model was checked. A satisfactory convergence of experimental and calculated temperatures with an accuracy of 10 % was established, which would suffice for the engineering calculations. The model built makes it possible to assess the fire resistance of unprotected reinforced concrete structures. Thus, there is reason to argue that the model constructed can partially or completely replace the experimental assessment of fire resistance, provided that the construction and setting of the model parameters are correct

A finite-element model was developed for thermal engineering calculation of a fire-resistant multi-cavity reinforced concrete floor in the ANSYS software complex. With the help of the developed model, a thermal engineering calculation of a fire-resistant reinforced concrete multi-hollow floor slab was carried out, the essence of which was to solve the problem of non-stationary thermal conductivity and was reduced to determining the temperature of the concrete of the reinforced concrete floor at any point of the cross section at a given time (including at the place of installation of the fittings).A comparison of the results of numerical modeling with the results of an experimental study of fire resistance was carried out. An approach is proposed that allows taking into account all types of heat exchange by specifying cavities as a solid body with an equivalent coefficient of thermal conductivity. The model makes it possible to study stationary and non-stationary heating of both unprotected and fire-protected reinforced concrete structures. At the same time, with the help of the developed model, it is possible to take into account various factors affecting fire-resistant reinforced concrete structures: fire temperature regimes, thermophysical characteristics of reinforced concrete structures, coatings for fire protection of reinforced concrete structures. The adequacy of the developed model was tested, as a result of which it was established that the calculated values of temperatures satisfactorily correlate with experimental data. The largest area of deviation in temperature measurement is observed at the 100 th minute of calculation and is about 3 ºС, which is 9 %. The workability of the developed model for evaluating the fire resistance of fire-resistant reinforced concrete structures and its adequacy to real processes that occur during heating of fire-resistant reinforced concrete structures with the application of a load under the conditions of fire exposure under the standard fire temperature regime have been proven.

Purpose. Development of a computer model for the study of fire resistance of steel structures protected by fire-resistant coatings, using the example of a fire-resistant steel beam created in the LIRA-SAPR software complex (Ukraine). Methods. Finite element method, application of computational methods of numerical modelling of the LIRA-SAPR software complex, mathematical modelling of thermal processes of non-stationary thermal conductivity. Results. A computer model was developed in the LIRA- SAPR software complex, with the help of which thermal engineering calculation of the beam was carried out. The model makes it possible to evaluate the fire resistance of both unprotected and fire-protected steel beams, to take into account the properties of the beam material and the material of the fire-resistant coating. The peculiarity of modelling the non-stationary heating of a fire-resistant steel beam is to specify the thermophysical characteristics of the fire-resistant coating when solving the problem of non-stationary thermal conductivity. The results of the calculated determination of the fire resistance of the fire-resistant steel beam were compared with experimental data. As a result, a satisfactory convergence of the results of the calculation and experimental study of fire resistance was established (the error is no more than 12%). The results of the experimental determination of the fire resistance of unloaded beams under fire conditions of the standard fire temperature regime were analysed. The accuracy of the developed computer model was evaluated with the results of the experiment. Scientific novelty. A finite-element model of a fire-resistant steel beam has been developed in the LIRA- SAPR software complex, which allows calculating the fire resistance limits of beams protected by fire-resistant coatings with scientifically justified parameters with sufficient accuracy for engineering calculations. Practical significance. It consists in creating the basis for the calculated assessment of fire resistance of building structures protected by fire-resistant coatings by creating computer models capable of performing fire resistance calculations. Due to this, there should be a significant reduction in the cost of work on fire resistance assessment and, as a result, an increase in the effectiveness of measures to increase the fire resistance of building structures.

A finite element model for thermal engineering calculation of fire-resistant multi-hollow reinforced concrete floor in the ANSYS software package has been developed. The model allows to evaluate the fire resistance of fire-resistant and unprotected reinforced concrete structures both under load and without it. With the help of the developed model, the heat engineering calculation of the fire-resistant reinforced concrete multi-hollow slab was carried out. The results of numerical simulation are compared with the results of experimental study of fire resistance. An approach is proposed that allows to take into account all types of heat transfer by specifying cavities as a solid body with an equivalent coefficient of thermal conductivity. The adequacy of the developed model was checked, as a result of which it was established that the calculated values of temperatures correlate satisfactorily with the experimental data. The largest deviation in the measurement of temperatures is observed at 100 minutes of calculation and is about , which is 9%.

Проведено аналіз результатів досліджень вогнестійкості залізобетонних конструкцій і встановлено, що сучасні підходи до оцінювання вогнестійкості не завжди дають змогу отримати оптимальні рішення для теплотехнічного розрахунку вогнезахищеної залізобетонної колони. Створення основ для ефективного оцінювання вогнестійкості вогнезахищених залізобетонних будівельних конструкцій з науково обґрунтованими параметрами вогнезахисних покриттів є актуальною проблемою, розв’язання якої призведе до підвищення точності теплотехнічного розрахунку вогнезахищених залізобетонних колон з необхідною для інженерних розрахунків досконалістю. З огляду на це розроблено комп’ютерну модель для моделювання нестаціонарного прогріву вогнезахищеної залізобетонної колони, що дає змогу оцінювати вогнестійкість як незахищених, так і вогнезахищених залізобетонних колон, враховувати властивості матеріалів колон та вогнезахисного покриття. Алгоритм оцінювання містить виконання експериментальних та розрахункових процедур під час визначення вогнестійкості вогнезахищених залізобетонних колон. За допомогою розробленої моделі проведено моделювання нестаціонарного прогріву вогнезахищеної залізобетонної колони за стандартного температурного режиму пожежі. Особливість моделювання нестаціонарного прогріву вогнезахищеної залізобетонної колони полягає у задаванні теплофізичних характеристик вогнезахисного покриття під час розв’язання задачі нестаціонарної теплопровідності. Під час визначення ефективності розробленої моделі було проведено порівняння результатів чисельного моделювання прогріву залізобетонної колони з результатами експериментального дослідження вогнестійкості залізобетонної колони. Також було запропоновано моделювання вогнезахисту залізобетонної колони для підвищення меж вогнестійкості до необхідних значень межі вогнестійкості. Підтвердженням адекватності розробленої моделі є задовільна збіжність експериментальних та розрахункових температур. Особливістю розробленої комп’ютерної моделі є можливість моделювання нестаціонарного прогріву вогнезахищених залізобетонних колон з урахуванням їх початкових та граничних умов, геометрії, характеристик матеріалів, класу бетону, класу арматури, теплофізичних характеристик вогнезахисних покриттів, умов випробувань та умов обігріву.

1. Structural Materials 1.1. Properties 1.2. Elastic Modulus 1.3. Yield Strength, Ultimate Tensile Strength, Ductility, Hardness 1.4. Plasticity: Dislocations 1.5. Work-hardening, Recovery and Recrystallization 1.6. Fracture Toughness 1.7. Fatigue 1.8. Creep 1.9. Corrosion and Oxidation 1.10. Wear 1.11. Summary of Structural Materials 2. Functional Materials 2.1. Optical Materials 2.2. Electrical Properties 2.3. Dielectrics 2.4. Magnetic Properties 2.5. Thermal Properties 2.6. Summary of Functional Materials Glossary Bibliography Biographical Sketch

Purpose. Evaluation of fire resistance of fire-resistant steel structures using the developed calculation and experimental method. Methods. Finite difference method, landfill fire test method, mathematical and computer modeling of non-stationary heat exchange processes, determination of thermophysical characteristics of fire-retardant coatings based on solving direct and inverse thermal conductivity problems. Results. Geometric, physical, computer models have been developed, with the help of which the fire resistance of fire-resistant steel structures has been evaluated by the calculation-experimental method. The adequacy of the developed method for assessing the fire resistance of fire-resistant steel structures in assessing the fire resistance of fire-resistant I-beam steel column has been checked. The analysis of tests on fire resistance of fire-resistant steel columns exposed to fire at the standard temperature of the fire without the load applied to them has been carried out. A computer model of the “steel column – reactive flame retardant coating” system has been built for numerical simulation of non-stationary heating of such a system. The fire resistance of fire-resistant steel columns of I-beam section without load applied to them has been evaluated using the calculation-experimental method. Verification of results of experimental research with results of numerical modeling has been carried out. Scientific novelty. The convergence of the results of experimental data on the duration of fire exposure at the standard temperature of the fire to reach the critical temperature of steel with the results of numerical simulations has been determined. Based on the comparison of the experimental results and numerical modeling, the adequacy of the developed model to the real processes that occur when heating fire-retardant steel columns without applying a load under fire conditions at a standard fire temperature has been confirmed. The efficiency of the proposed calculation and experimental method for assessing the fire resistance of fire-resistant steel structures has been confirmed. Practical significance. It consists in the implementation of the results on objects of different purposes in assessing the fire resistance of fire-resistant steel structures by evaluating the effectiveness of fire-retardant coatings of steel building structures.

This paper presents the results of fire test of an I-beam protected by a combined magnesite plate-magnesite mixture heat-insulating material. It was shown that a composite with an average thickness of 37 mm maintained an average temperature of 380 °C on the metal surface after 150 minutes of fire exposure, not exceeding the critical value of 500 °C. From 60 to 100 minutes of fire testing (furnace temperature of 980-1025 °C), the temperature of the metal did not exceed 100 °C. This was achieved both due to the high thermal insulation properties of the magnesite mixture, and due to gas and vapor release from the hydration products of magnesia cement. The developed fire-retardant material provides the first group of fire-retardant efficiency (150 minutes) and, after the fire test, is characterized by density of 352.4 kg/m 3 and compressive strength of 0.85 MPa, which is three times lower than the original.

Abstract. The results of the development of fire-retardant substances based on domestic materials to increase the fire resistance of fire-retardant steel structures are presented. New compositions of fire-retardant substances on the basis of domestic materials capable of swelling are developed. A series of experimental studies to determine the heating temperature of fire-resistant steel structures. For this purpose, samples of reduced size in the form of a steel plate with a flame retardant applied to the heating surface were used. Fire tests of fire-retardant steel plates coated with the developed fire-retardant substance forming a coating on the protected surface, in the conditions of their tests on the standard temperature of the fire using the installation to determine the fire-retardant ability of fire-retardant coatings. The results of experimental determination of temperature from an unheated surface of steel plates with a fire-retardant covering in the conditions of fire influence at a standard temperature mode of a fire are analyzed. Based on the obtained data (temperature in the furnace and from the unheated surface of steel plates with fire protection system) the solution of the inverse problems of thermal conductivity found thermophysical characteristics of fire protection coating (thermal conductivity and specific volume), which can be used for thermal calculation heating of fire-retardant steel structures at arbitrary fire temperatures. The thermophysical characteristics of the formed fire-retardant coating are substantiated to find the characteristics of the fire-retardant ability of the newly created fire-retardant coating and to ensure the fire resistance of fire-retardant steel structures. The efficiency of the developed fire-retardant coating for protection of steel structures is proved.

The results of the experimental determination of temperature from a non-heating surface of steel plates with a fire-protective coating under conditions of fire exposure under the hydrocarbon fire temperature regime are presented. A calculated finite element model of the system “steel plate-flame retardant” was constructed to simulate the non-stationary heating of such a system in the ANSYS R17.1 software complex. The reliability of the numerical simulation results is estimated by real test, the adequacy of the developed model to the real processes occurring when heating the steel plates with fire-protective coating under the conditions of hydrocarbon fire temperature mode is made.

Physical and mathematical models for assessing the fire resistance of fire-resistant steel structures have been developed. An algorithm is used, which includes experimental and computational procedures in determining the fire resistance of fire-resistant steel structures. The initial and boundary conditions for the construction of these models are formulated, which allow to predict the fire resistance of the fire-resistant steel structure with sufficient accuracy for engineering calculations. The peculiarity of the developed models is taking into account the thermophysical characteristics of steel structures and fire-retardant coatings, the peculiarities of the formation of fire regimes. Based on the proposed physical and mathematical models, a computational and experimental method for estimating the fire resistance of fire-resistant steel structures has been developed. The adequacy of the developed method was checked when assessing the fire resistance of a fire-retardant steel column. A computer model of a fire-retardant steel column was built to simulate non-stationary heating of such a system in the FRIEND software package. The results of determining the convergence of experimental data on the duration of fire exposure at the standard temperature to reach the critical temperature of steel with the results of numerical simulations in the software package FRIEND. Based on the comparison of the experimental results and numerical simulations, a conclusion is made about the adequacy of the developed model to the real processes that occur when heating fire-retardant steel columns without applying a load under fire conditions at standard fire temperature.