Short-term Dynamic Loading Research Articles

Utilizing construction and demolition waste in concrete as a sustainable cement substitute: A comprehensive study on behavior under short-term dynamic and static loads via laboratory and numerical analysis

This study explores the utilization of recycled concrete powder (RCP) as a sustainable alternative to conventional cement in concrete production, focusing on its impact on mechanical properties and impact resistance. Two series of concrete mixtures were prepared: one without and one with 0.5 % polypropylene fibers by RCP-replacing cement at varying proportions (0 %–50 %). Methodologically, the research involved both laboratory tests and predictive modeling using artificial neural networks (ANN) and fuzzy logic (FL). Laboratory evaluations assessed compressive, flexural, and tensile strengths under static loads, as well as impact resistance through repeated drop weight impact (RDWI) tests. Key findings reveal that RCP-incorporation of 15 % leads to negligible reductions in compressive, flexural, and tensile strengths, while higher replacements significantly decrease performance. The addition of polypropylene fibers notably improved mechanical properties across all RCP replacement levels, enhancing compressive strength by up to 23.65 % and flexural strength by 27.49 % at the upper limits of RCP substitution. Accurate predictions of 28-day compressive strength were achieved via the ANN model with an average prediction error less than 1 %. The study also validates that the Weibull distribution effectively describes the impact resistance of concrete mixtures, confirming the advantages of combining RCP with fiber reinforcement to achieve sustainable and high-performance concrete solutions.

Experimental study on deformation characteristics of new prestressed subgrade under static and dynamic loads

An in-deep comprehension of the static and dynamic operational characteristics of prestressed subgrade is essential for its analysis, design, and service performance evaluation. Based on the Buckingham π theory, a novel scaled static and dynamic model test system of the prestressed subgrade has been developed. The structural components, functional characteristics, and working mechanism of the test system were comprehensively elucidated, and a suite of static and dynamic model tests was conducted to study the deformation characteristics of the prestressed subgrade. It is demonstrated that the prestressed steel bars underwent prestress loss due to the additional stress induced creep of the soil elements below and adjacent to the load transfer plates (LTPs). Therefore, it is advisable to over-tension the prestressed steel bars in practical engineering. Upon the application of prestress, the subgrade surface experienced slight uplift deformation, which did not change the geometric shape and smoothness of the subgrade surface and demonstrated that the prestress reinforcement effect could diffuse to the subgrade surface. In the static double-load-plates tests, the prestressed subgrade presented obvious advantages in controlling the subgrade surface settlement and slope lateral deformation compared to the unreinforced subgrade, which could therefore improve the deformation resistance of the subgrade. In the short-term dynamic loading tests, both the acceleration and dynamic displacement of the subgrade approximately linearly decreased with an increase in the prestress, implying that the horizontal prestress had a notable beneficial impact on mitigating the subgrade vibration. Additionally, with the long-term dynamic loading, the prestress reinforcements could significantly restrain the cumulative plastic deformation of the subgrade, with the cumulative deformation decreasing as the applied prestress increased. The developed test system offers viable and implementable technical means for investigating the enhancement mechanism of a prestress reinforced subgrade, and the insights gained from the tests contribute to elucidating the effect of prestress reinforcements on the subgrade’s static and dynamic performance.

Development of a mathematical model of dynamic soil deformation taking into account the variable coefficient of volumetric viscosity

Determining soil deformations under the influence of dynamic loads of different nature, including during military actions, is an important scientific and practical problem. At the same time, when solving problems of determining the stress-strain state of soils under the action of short-term dynamic loads, little attention has been paid to the multicomponent composition and viscous properties. The aim of the research is to develop a mathematical model of soil deformation taking into account the variable coefficient of volumetric viscosity both during loading and unloading. The methods of mathematical modeling and numerical integration are used in the research. The possibility of using the proposed model to determine the deformation of soils under explosive and shock loads is shown, which helps control the properties of soils for the protection of shallow underground structures. The results of a comparison of the obtained analytical data with the experimental data are presented.

EXPERIENCE IN CREATING STANDS FOR TESTING REINFORCED CONCRETE STRUCTURES OF CRITICAL OIL AND GAS FACILITIES

Link for citation: Odnokopylov G.I., Sarkisov D.Yu. Experience in creating stands for testing reinforced concrete structures of critical oil and gas facilities. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 10, рр. 140-152. In Rus. The relevance of the work is caused by the increased probability of short-term shock and explosive dynamic loads due to terrorist acts and other emergency situations affecting the construction structures of critical buildings and structures of oil and gas facilities. An example of such impacts is the recent terrorist attack on the Nord Stream gas pipelines. Due to the large number of parameters affecting the physical process of deformation of structures with this type of impact, experimental research is currently an integral part of scientific research in this area. Such studies are especially relevant for reinforced concrete structures, which, on the one hand, are very widely used in construction, and on the other, have a complex nonlinear nature of deformation. To conduct experimental research, it is necessary to design and implement specialized stands, with the help of which it is possible to create a short-term dynamic effect on the structure. A review of the literature data has shown that test stands based on drop-weight stands are most often created for conducting such studies. In such stands, the energy of a falling load is used to destroy structures. It follows from the above that the design and improvement of stands for research of reinforced concrete structures on the effect of short-term dynamic loads is an urgent task of practical importance. The purpose of the work is to describe the structures of the test stands created on the basis of the drop-weight stand in the laboratory of the Reinforced Concrete and Stone Structures Department, Tomsk State University of Architecture and Building, to identify their main advantages and indicate disadvantages; as well as to state further development paths in the field of design and implementation of such stands. Methods: theoretical analysis of literature and Internet sources, modeling, experimental research. Results. Various modifications of test stands based on a drilling rig for research of reinforced concrete structures have been designed and implemented. The main advantages and disadvantages of such stands are shown and further ways of their development are formulated.

Studies of spun concrete poles for electric power transmission line supports reinforced with Au1000P rebars

Introduction. In connection with the present volumes of electrification in central Russia, the need for the construction of new electric power transmission lines (EPTLs) has decreased considerably. At the same time, the natural degradation of EPTL supports in time, as well as the prospects for developing the vast expanses of the northern, Siberian and Far Eastern regions, caused by the reorientation of Russia’s economic relations from the West to the East, make it urgent to increase production volumes and technical and economic efficiency of using spun reinforced concrete poles for EPTL supports.Aim. Industrial implementation of spun reinforced concrete poles with the high-strength innovation profile reinforcement by replacing A800 rebars with four-row-profile Au1000P rebars.Materials and methods. The article provides data on the full-scale tests of spun reinforced concrete poles for EPTL supports according to the GOST 22687.1-85 “Centrifugal cylinder reinforced concrete posts for high-voltage transmission lines. Structure and dimensions” [1]. Three pole samples with a length of 26 m were prepared and tested. One sample consisted of prestressed A800 rebars according to GOST 22687.1-85, while the other two prototypes include the prestressed Au1000P rebars with the four-row profile. In the second sample, the reinforcement scheme (diameters and rebar quantity) repeats the standard option, increasing the bearing capacity of the pole. Having the same bearing capacity as the pole, manufactured according to the GOST, the third sample promoted for the reduction in the quantity of non-stressed rebars.Results. A new scheme for reinforcing the pole sample using Au1000P rebars was developed. The results of the sample testing are presented; a comparative evaluation of the pole strength and deformation characteristics is given; technical and economic indicators, as well as the recommendations regarding the reinforcement of the prestressed spun concrete poles with Au1000P rebars are provided.Conclusion. According to the results of the performed study, an economic effect was established due to a reduction in the quantity of non-stressed rebars by 28 %. Poles with Au1000P prestressed rebars have an increased corrosion resistance and durability due to the closing of cracks formed during the impact of short-term dynamic loads from wind gusts, wire breaks, etc. In terms of a recommendation, it is proposed to update the GOST 22687.1-85 in order to use new types of high-strength reinforcement rolled products and higher strength concrete.

Reliability analysis and experimental investigation of impact resistance of concrete reinforced with polyolefin fiber in different shapes, lengths, and doses

Fiber-reinforced concrete (FRC) in applications such as airport runway pavements, road construction, military bunkers, bridges, and dams are always exposed to short-term dynamic load. The present study follows the laboratory and statistical investigation of the impact resistance of polyolefin fibers reinforced concrete (PFRC). Polyolefin fiber was used in two different shapes (simple and mesh), three different lengths (19, 30, and 50 mm), and replacement percentages of 0.5%, 1%, and 1.5%. In order to evaluate the mechanical properties of PFRC, tests include compressive, indirect tensile, and impact tests. The compressive strength test was performed on 39 cubic samples (10 × 10 × 10 cm) and the indirect tensile strength was measured using 39 cylindrical samples (10 × 20 cm) at the age of 28 days. To investigate the impact resistance of concrete mixtures, 416 concrete discs with dimensions of 6.4 × 15 cm (resulting from cylindrical samples with dimensions of 30 × 15 cm) were subjected to a drop-weight test according to the recommendation of ACI 544. The drop-weight test data including the first crack strength and failure strength were collected. A comprehensive two-parameter Weibull distribution was implemented to accurately check the scattered results from the impact test, and the reliability function was presented. Therefore, the investigation shows that the Weibull distribution has a good performance in predicting the impact failure strength of concrete reinforced with polyolefin fibers and avoids conducting additional costly experiments. In addition, mesh fibers have a better performance than simple fibers in improving the mechanical strength of concrete. Polyolefin fiber with a length of 19 mm recorded better results than other lengths of this fiber.

Analytical calculation of bending elements with basalt fiber and glass composite rod reinforcement under short-term dynamic loading

During the construction and operation of buildings and structures, in addition to static loads, short-term dynamic impacts may occur on building structures and their elements caused by explosions, accidents, etc. As a result, damage or destruction of structures may occur, which leads to possible loss of life and significant material losses. Taking into account the influence of such impacts on the load-bearing capacity of building structures is relevant. A significant number of works by domestic and foreign authors are devoted to methods for calculating bending reinforced concrete elements under static and short-term dynamic loading. In the overwhelming majority, bendable concrete elements with steel rod and/or fiber reinforcement are considered as the object of research. The issues of predicting and assessing the stress-strain state of bending concrete elements reinforced with glass-composite reinforcement and/or basalt fiber under short-term dynamic loading have not been sufficiently studied. The current building codes consider calculations of such elements only under the action of static loads.

Strength and deformability models of cellular structure shells at static and short-term dynamic loading

The paper presents the results of a comprehensive experimental and numerical study of the destruction of reinforced beams made of concrete and fibroconcrete under short-term dynamic action. Experimental studies on were carried out on a copra rig. A short-term dynamic load on the beam was created with the help of a falling load weighing 450 kg from a height of 700 mm. In experiments, the magnitude of the dynamic load was determined using a force gauge sensor, linear displacement sensors were used to calculate linear displacements. Numerical modeling is carried out in a full three-dimensional dynamic formulation within the framework of the phenomenological approach of continuum mechanics with the explicit allocation of reinforcing elements. For the numerical solution, the finite element method is used, modified to solve dynamic problems. In the calculations, the impact of the load on the beam was replaced by an impulse. The dependence of the pulse on time was determined from the experiment. The effect of reinforcement on the deformation and destruction of the beam is investigated. The comparison of experimental and numerical results is carried out.

Punching shear strength under static and dynamic loads

Modern domestic calculation methods and developed countries for determining the bearing capacity of monolithic reinforced concrete slabs for punching do not fully take into account all factors of design solutions and operating conditions. The available design provisions are made for the static operation of structures and there are no recommendations for taking into account the features of the dynamic impact on the overlap and the nature of the work of the node interfaces. The accepted empirical assumptions of the calculation, based on numerous experimental data, do not take into account the features of the stress-strain state of the coupling of the overlap with the column during destruction according to the punching scheme. This is due to the lack of computational models in which all the acting internal forces ensuring the resistance of the interface to penetration would be considered comprehensively. The complexity of the problem is due to the fact that the sections of the nodal interface are in an inhomogeneous stressed state. The stress-strain state of plates for punching under dynamic load is currently little studied. This article proposes a method for determining the bearing capacity of a symmetrical nodal coupling of a column with an overlap for punching under static and short-term dynamic loading. The proposed design model of the punching strength is based on the following prerequisites: the resistance to punching of a monolithic reinforced floor consists of the shear resistance along the surface of the reduced punching pyramid formed by the height of the compressed concrete zone; the strength of the concrete shear resistance increases due to volumetric compressive forces on the surface of the reduced punching pyramid; the angle of inclination of the faces of the punching pyramid depends on the loading speed. The obtained theoretical dependences are applicable under static and dynamic loading and are in satisfactory agreement with experimental data.

ЖЕЛЕЗОБЕТОННЫЕ БАЛКИ С УЧЕТОМ РЕАКЦИИ РАСПОРА ПРИ КРАТКОВРЕМЕННОМ ДИНАМИЧЕСКОМ НАГРУЖЕНИИ

The article presents the results of theoretical studies of reinforced concrete beams, taking into account the limitation of horizontal displacement on supports under short-term dynamic loading. In studies, the deformation of the structure is considered in the conditionally elastic and plastic stages. It has been established that the presence of thrust leads to a significant increase in strength and a decrease in the deformability of structures, both in the conditionally elastic and plastic stages. The paper reflects the results of a numerical calculation of reinforced concrete beam structures with thrust under short-term dynamic loading based on the obtained analytical dependencies. The effect of the thrust reaction, namely the rigidity of the support contour, on the dynamic coefficient of reinforced concrete structures is considered in comparison with structures without expansion. The results of numerical studies indicate a positive effect of the expansion reaction in dynamically loaded structures at all stages of their dynamic deformation.

METHOD OF ASSESSING THE DURABILITY OF ASPHALT CONCRETE COATING USING BAKHALT FIBER ON HIGHWAY BRIDGES

In the article, based on literature analysis [1-3], a basic calculation scheme was developed for determining horizontal normal stresses in reinforced asphalt concrete coating with basalt fiber on reinforced concrete road bridges, taking into account the different time of action of the load of vehicles, which causes tensile stresses. A method for assessing the durability of asphalt concrete pavement with basalt fiber on reinforced concrete road bridges is proposed, which is aimed at increasing its crack resistance by improving design. Such design consists in the construction and calculation taking into account the repeated application of static and short-term dynamic loads of vehicles. The choice of the durability condition based on the limit state criterion for evaluating the crack resistance of the reinforced asphalt concrete pavement with basalt fiber is substantiated, taking into account the different time of the load and temperature. A method of assessing the durability of asphalt concrete pavement using basalt fiber on reinforced concrete road bridges and the sequence of its design has been developed.

ДИНАМИЧЕСКИЙ РАСЧЕТ ЖЕЛЕЗОБЕТОННЫХ БАЛОК НА ПОДАТЛИВЫХ ОПОРАХ ЗА ПРЕДЕЛАМИ УПРУГОСТИ

Protective structures of civil defense are designed from the condition of perception of short-term dynamic loads. In this case, the supporting structures can be deformed in the plastic stage. To reduce the forces and displacements of the bearing elements under intense dynamic loading, the active methods of protecting structures are used. The flexible supports in the form of collapsible inserts of annular section is one of such methods. The paper considers the change in displacements and forces of the elastic-plastic reinforced concrete beams, depending on the compliance of support fastenings. Based on the theoretical studies, an algorithm for the dynamic calculation of reinforced concrete beams with cracks was developed, with which the calculation of structures was performed under various conditions of deformation of yielding supports. The calculations showed that the use of yielding supports deformed only in the elastic stage can have both a positive and a negative effect on the operation of structures. In this case, there may be the areas of ωθ values in which there is an increase in the dynamic coefficient of the structure on yielding supports relative to the beams on non-displaceable supports. The greatest efficiency of using the yielding supports is achieved when they work at the plastic stage without transition to the hardening stage.

Strength of Normal and Inclined Sections of Bent Reinforced Concrete Elements with Zone Reinforcement Made of Steel Fiber

On the basis of theoretical and experimental studies, the prerequisites and the method of calculation of bent and compressed-curved reinforced concrete structures with zone reinforcement made of steel fiber, working under static and short-term dynamic loads, are formulated. In the developed method for calculating the strength of normal and inclined sections, a nonlinear deformation model is implemented, which is based on the actual deformation diagrams of materials. The developed calculation method is brought to the program of calculation of reinforced concrete structures with zone reinforcement of steel fiber under short-term dynamic loading, taking into account the inelastic properties of materials. The numerical studies made it possible to determine the influence of various parameters of steel-fiber reinforcement on the strength of reinforced concrete elements. To confirm the main results of the developed calculation method, experimental studies of reinforced concrete beam structures reinforced with conventional reinforcement and a zone steel-fiber layer are planned and carried out. Experimental studies were carried out under static and short-term dynamic loads. As a result of the conducted experiments, data were obtained that characterize the process of destruction, deformation and cracking of steel-reinforced concrete elements under such types of loading. The dependences of changes in the energy intensity of reinforced concrete structures with zone reinforcement made of steel fiber in the compressed and stretched cross-section zones under dynamic loading are obtained. The effectiveness of the use of fiber reinforcement of normal and inclined sections of bent and compressed-curved elements to improve the strength and deformative.

ПРОЧНОСТЬ СЖАТЫХ И ВНЕЦЕНТРЕННО СЖАТЫХ ЖЕЛЕЗОБЕТОННЫХ ЭЛЕМЕНТОВ С ЗОННЫМ АРМИРОВАНИЕМ ИЗ СТАЛЬНОЙ ФИБРЫ

The real nonlinear diagrams of concrete, reinforcement and steel-fiber concrete under dynamic loading are formulated and analytically described. Theoretical and experimental studies of the operation of compressed and non-centrally compressed elements with different levels of load application eccentricity under static and short-term dynamic loads are carried out. 3 reinforced concrete and 9 steel-fiber concrete elements were manufactured and tested for short-term dynamic load under central and off-center compression. New experimental data characterizing the process of deformation and destruction of steel-reinforced concrete models of columns have been obtained. Also, the schemes of destruction and cracking, the dependence of changes in the dynamic load over time, the movement of concrete, reinforcement and steel-fiber concrete over time are obtained. A method has been developed for calculating the strength and stability of such elements, taking into account the reinforcement of the section with steel fiber concrete. The influence of the use of zone reinforcement with steel fiber of compressed and non-centrally compressed reinforced concrete elements is numerically analyzed. The results of the calculation according to the developed methodology are compared with the results of experimental data. The optimal variant of the application of zone reinforcement made of steel fiber for compressed and non-centrally compressed elements operating under static and short-term dynamic loads is proposed. The analysis of the calculation results based on the developed method for calculating the strength of normal sections of non-centrally compressed reinforced concrete and steel-fiber concrete, based on the deformation model, and their comparison with the data of experimental studies under short-term dynamic loading show that the deviations are on average 10-18 %, which indicates that the developed method has sufficient accuracy to solve practical problems.

Analysis of changes in the survivability of building structures reinforced after an emergency dynamic impact in the context of assessing the security of buildings in the oil and gas industry

The relevance of the subject matter is conditioned by the technical complexity of the oil and gas facilities due to the increase in the volume and rate of raw materials production, which may be affected by shock-wave loads in emergency situations. The causes of the impact can be explosions, heavy cargo falls, terrorist attacks, natural and anthropogenic disasters, etc. These situations are very likely to cause significant damage to the building structures of industrial facilities, which necessitates their reinforcement. For further safe operation of the facility, reinforced structures must have survivability under repeated impacts no less than before the reinforcement. Given the fact that the survivability of buildings is a complex characteristic influenced by many factors, and it itself is a component of the security of a hazardous production facility, research in this area is topical. The purpose of the study is to test the developed method for assessing the survivability of a building structure under short-term shock-wave load based on the energy parameter and to analyze the results obtained in the context of assessing the security of critical oil and gas facilities. Research methods: Measurement of accelerations, deflections, and loads by strain measurement methods, graphoanalytical method of study using the Microsoft Excel software. A method for assessing the level of survivability of a building structure under shock-wave loading for critical oil and gas facilities using the survivability coefficient is developed. Using specific tests of conventional and cage-reinforced bending concrete elements for short-term dynamic load, the values of the specified coefficient are obtained. The values are compared and conclusions are drawn.

Numerical and experimental studies of deflections of conventional and strengthened reinforced concrete bendable elements under short-term dynamic loading

The relevance of this study is conditioned by the technical complexity of the design solutions for construction projects of ground-based space infrastructure. It is associated with the possibility of special loads in the form of an air shock wave in the event of a launch abort, a fall of a fragment, an emergency shutdown of engines, an air shock wave from the indirect impact of nuclear weapons, seismic loads, accidental cargo falls, terrorist attacks, etc. Such impacts with a high degree of probability lead to damage to building structures and in the future, they need to be reinforced. These building structures must have survivability under special loads and deform without collapsing. Under the dynamic loading, the energy intensity of the bendable structures is important, to determine which it is necessary to know the magnitude of the acting force and deflections. The effective load in a wide class of problems refers to the initial data, and the determination of reliable values of the dynamic deflection of the bendable structure is an actual problem. The purpose of this study is to conduct a numerical and experimental investigation of the deflection of conventional and strengthened reinforced concrete structures under short-term dynamic loading. This study used the following research methods: measurements of deflections and loads by strain measurement, graphical analytic research using Microsoft Excel, numerical calculation in the environment of the Explicit Dynamics module of the Ansys software package. As a result of the study, experimental investigation of conventional and strengthened bendable reinforced concrete elements under short-term dynamic loading was carried out, the values of the effective force and deflections were obtained. The same experiment was modelled in the environment of the Explicit Dynamics module of the Ansys software package. A comparison of the deflection parameters was made, based on the results of numerical and physical experiments on the example of a specific design, which showed satisfactory convergence.

The degree of survivability of building structures under dynamic loading

The relevance of the work is due to the increasing possibility of impact on the critical building structures of industrial buildings of short-term dynamic loads in abnormal emergencies. These situations lead to significant damage of the constructions of buildings. There is a high possibility of human victims and significant damage of expensive technological equipment when the structures collapse. Therefore, in order to ensure further functioning of the structure, it is necessary to design building structures as well as the object on the whole with the properties of survivability under non-stationary impact. Such properties should be analyzed when constructing scenarios of origination and development of emergency situations as well as analyzing risks. In the course of the research the strain gauge methods were used to measure deflections, accelerations and loads on the samples. The work proposes a method for assessing the degree of survivability of a critical building structure under short-term dynamic loading based on the analysis of the energy parameter. Using the example of a specific test of a bending reinforced concrete element for short-term dynamic load the values of the specified coefficient were obtained.

METHOD OF CORRECTION OF THE PSYCHOPHYSICAL CONDITION OF PRESCHOOL CHILDREN WITH FREQUENT RESPIRATORY DISEASES BY ADAPTIVE PHYSICAL TRAINING

The article considers the possibilities of using the method of adaptive physical training in preschool education to correct the psychophysical condition of children with frequent respiratory diseases. The main directions of implementation of the method psychophysical condition correction for preschool children with frequent respiratory diseases by means of adaptive physical education were identified. The health improvement direction has the purpose to increase the optimization of all body systems. The forming direction aims to form such social qualities as perseverance, patience, courage, determination and strong-willed qualities. Educational direction provides the acquisition of systematic knowledge about the methods and techniques of strengthening the body, the timely development of motor skills and abilities, the rules of a healthy lifestyle. The main means of implementing this technique were identified among the following means of adaptive physical education: hyperventilation training, exercises on breathing simulators, exercises with a moderate load on the upper extremities, educational games-exercises, games-travel, dosed walking. Appropriate methods of work with preschool children who often suffer from respiratory diseases, such as doing of cyclic exercises; performing short-term dynamic loads at short intervals; filling in intervals with relaxation exercises or breathing exercises; use of dynamic and static breathing exercises of moderate intensity; application of speed and strength exercises are presented in the article. The effectiveness of the proposed method of correction of psychophysical condition for preschool children was determined by noticing of physical indicators during the performance of various tasks and psychological test methods.

Deformation Dependences of the Power and Environmental Resistance of Reinforced Concrete Structures Under Accidental Actions

The problem of determining the parameters of the stress-strain state of reinforced concrete bending elements with the simultaneous manifestation of force loading and environmental impact under static-dynamic loading conditions is considered. Dependences of the deformation model were constructed using the integral modulus of deformations by V M Bondarenko. The parameters of the diagrams of the static-dynamic deformation of the section of corroded concrete under the action of a static and short-term dynamic load are determined on the basis of a rheological two-element model of concrete deformation of the theory of plasticity by G A Genieva. At the same time, the hypothesis was accepted that the relationship between stresses and strains in corrosion damaged concrete under its short-term loading is affinity-like to similar dependencies of undamaged concrete, and the ultimate deformations of concrete under static and static-dynamic loading modes are equal to each other. A methodology and an algorithm for the computational analysis of the strength and environmental resistance of reinforced concrete structures at all stages of static-dynamic deformation are proposed.

ПРОЧНОСТЬ ИЗГИБАЕМЫХ ЖЕЛЕЗОБЕТОННЫХ ЭЛЕМЕНТОВ С ЗОННЫМ АРМИРОВАНИЕМ ИЗ СТАЛЬНОЙ ФИБРЫ

On the basis of theoretical and experimental studies, the assumptions and calculation method for flexible and compressed-curved reinforced concrete structures with zone reinforcement made of steel fiber operating under static and short-term dynamic loads are formulated. In the developed method for calculating the strength of normal and inclined sections, a nonlinear deformation model is implemented, which is based on the actual deformation diagrams of materials. To confirm the main results of this method, numerical and full-scale experimental studies of reinforced concrete beam structures reinforced with conventional reinforcement and a zone steel-fiber layer were planned and carried out. Experimental studies were carried out under static and short-term dynamic loads. As a result of the conducted experiments, data were obtained that characterize the process of destruction, deformation and crack formation of steel-reinforced concrete elements under such types of loading. The efficiency of fiber reinforcement of normal and inclined sections for increasing the strength and deformation characteristics of reinforced concrete structures is revealed.