A methodology and an algorithm for calculating the survivability parameters of a long-term deformable reinforced concrete building frame in extreme states are presented. Analytical dependencies for determining the value of the creep measure are taken in accordance with the use of approximate dependencies from the recommendations of the NIIZHB. On this basis, a method is proposed for determining the cross-section bending stiffness of the frame elements. The deformation criterion of a special limiting state is formulated taking into account the nonequilibrium processes of prolonged deformation of the structural system elements. The numerical analysis results of the long-term deformable reinforced concrete frame survivability potential with a sudden removal of the one structural element, taking into account the long-term deformation prehistory of the considered building frame under an operating load, are presented. The exposure of the structural system survivability from the its loading moment to its transformation into a kinematically variable system has been determined.
In contemporary European literature, the problem of shaping future educators against the backdrop of crisis (military) transformations has not been explored. Ukrainian teachers demonstrate valuable experience in the teaching under warfare conditions, which should be the subject of a separate study. In addition, the problem of the professional formation of future teachers is also relevant, given the numerous terminological debates between scientists. The article aims to analyze the formation of professional competence of future elementary school teachers against the background of large-scale military aggression. The work is formed on the use of theoretical pedagogical research methods. Noticeable attention is paid to the methods of generalization, abstraction, analysis, synthesis. Among the empirical methods, the methods of experiment and SWOT-analysis were used. With the help of the latter, the strengths and weaknesses of the formation of professional competence in the system of distance learning of future elementary school teachers against the background of military aggression are reflected. The results considered terminological discussions regarding the concept of “professional competence”, highlighted the main features of professionalism of modern teachers, analyzed the use of game techniques and their impact on the formation of important skills for future teachers, developed a training model to ensure maximum exposure to professional competence in future teachers. In the conclusion, it was noted that the appeal to game techniques allows to deepen the assimilation of professional competence, moreover, conducting games during the war has an additional psychological effect. The best training model for future teachers is to conduct distance learning sessions according to the established program, which provides an increase in the amount of practice and actualization of the experience of independent work.
In this paper, results of numerical investigations of prefabricated RC structural systems, in particular influence to deformation at sudden bearing element removal it cross section, node links, reinforcement scheme and prestressing, are presented. It is shown, that it is possible to increase structural safety varying these parameters. Structural decisions of prefabricated elements, its nodes, recommendations for prestressing, which provide resistance against progressive collapse, are proposed.
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.
In the framework of ultimate state calculation methods the paper presents some propositions for stress-strain state, crack resistance analysis and failure state of reinforced concrete structures with corrosion damage at supports. The work concerns the durability of concrete and reinforced concrete elements with corrosion damage. The theory for reinforced concrete with corrosion damage is presented for plane stress state
Орловский государственный университет им. И.С. Тургенева, г. Орел, Россия Аннотация. Рассмотрена классификация методов защиты от прогрессирующего обрушения по трем основным категориям: меры вторичной защиты, косвенное проектирование и прямое проектирование. Приведен анализ требований по защите зданий и сооружений от прогрессирующего обрушения в законодательно-правовых и нормативных документах России и стран Евросоюза. Рассмотрены конкретные положения российских и европейских нормативных документов по проектированию устойчивости несущих конструкций зданий и сооружений против прогрессирующего обрушения. А именно приведено сравнение требований по определению комбинаций нагрузок, значению особой нагрузки, к параметрам зоны ограничения локального разрушения в нормативных документах России, США, стран Евросоюза. Выполнен анализ экспериментально-технических исследований строительных конструкций при особых воздействиях. Большинство экспериментальных исследований проводились на железобетонных, стальных и композитных конструкциях, мало внимания уделяется исследованиям каменных и деревянных конструкций в этой области.
The problems of calculating the parameters of non-equilibrium power and environmental resistance of reinforced concrete elements of a structural system under special effects are considered. A static-dynamic diagram of the deformation of corrosion-damaged concrete during overlimit impact caused by the sudden removal of a supporting structure is constructed. The section of this diagram is described by the analytical dependence for change in the strength of loaded and corrosion-damaged concrete from time, which takes into account, on the one hand, the process of the increasing strength of “healthy” concrete in time (theory of concrete aging), and on the other, the process of the degradation of an aggressive environment on concrete. A section of the dynamic deformation diagram is described by the Kelvin-Voigt model in a version of the theory of plasticity of concrete G.A. Genius, which corresponds to the conditions of deformation of concrete as an elastic-viscous-plastic material. The dynamic tensile strength of corrosion-damaged concrete is taken into account by the coefficient of increase in the dynamic strength of the material based on the two-element model of its deformation.
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