Vol 15, No 4 (2019)

Aims of research. The article is devoted to actual problems of computational analysis of stress-strain state, strength and stability of load-bearing structures with allowance for the main and special combinations of loads and impacts, comparison of the results of alternative structural analysis of unique cultural and business complex “Congress Hall” in Chelyabinsk. The natural conditions of the area of location of this object and main load-bearing structures of the object are described. Besides, characteristic and design loads, their combinations, formulation of objectives of computational research and methods of solution are presented. Methods. Space discretization and solution of the corresponding problems of mathematical (numerical) and computer modelling of the considering unique building were carried out with the use of finite element method. Detailed finite element models of the coupled system “combined foundation - loadbearing structures” and its fragments (subsystems) were developed and verified. They adequately reflect geometric-stiffness, inertial and load parameters of the object and the resulting stress-strain state. Progressive collapse analysis are under consideration as well. Licensed, certified and verified (by the Russian Academy of Architecture and Construction Sciences) finite element software package “ANSYS Mechanical” was used. Results. The resulting parameters of stress-strain state, strength and dynamics of load-bearing structures of the building with allowance for design (in accordance with design codes) combinations of vertical and wind loads are considered. Besides, information about results of progressive collapse analysis is presented. Thus, a reasonable conclusion is made about the reliability of the criterion parameters of strength, stability and dynamics of the load-bearing structures of the object.

Aims of research. The task is to apply modern strength criteria of anisotropic materials for the calculation of multilayer walls made of cellular concrete and silicate large masonry materials, which differ in exact dimensions and allow for thin-seam masonry with adhesive seams. Proposals for the inclusion in the design standards of guidance that takes into account the work of wall materials in complex stress states will be presented in a series of publications. Methods. The strength criteria of G.A. Geniev in a rather simplified form are used. The volumetric stress state of walls made of orthotropic materials is considered. The basis for the construction of strength criteria are three possible different mechanisms of destruction - separation, compression and shear. For modern thin-walled masonry is characterized by a combination of compressive (vertical) and shear (horizontal) loads. Of particular interest is the work of the masonry shift, since the plane stress state is not sufficiently studied. The article is devoted to the construction of the criterion of masonry shear strength. The peculiarity of the proposed calculations is the comparative simplicity of the strength criteria due to the accepted hypotheses. Results. The final expression of the shear strength criterion and the sequence of the shear strength verification in the case of simple loading are presented. The article is preliminary for a series of calculations and results of experimental studies of the walls under different operating conditions and different loads.

Aims of research. The research is aimed at determining the critical buckling load at which the shell interacting with the soil loses equilibrium stability, and finding the buckling mode of the shell in the linear and nonlinear formulations of the task. Methods. The task is solved by a numerical method using a finite element complex, which allows investigating the stress-strain state and assessing the equilibrium stability of beam models and two-dimensional models of the round cylindrical shell. Three design cases of the beam model and two design cases of the two-dimensional model interacting with the soil are compiled. There is a load summary acting on the shell. The calculations are carried out in linear and geometrically nonlinear formulations using a linear elastic model of the material. Contact elements of one-side and two-side action are used. Critical buckling load are determined relative to the actual load of its own weight. Results. Critical buckling load are determined and the buckling mode of the round cylindrical shell interacting with the soil are found. There is a comparative analysis of the results. An assessment of the stability margin of the shell relative to the actual load is given.

Aims of research. The use, design and analysis of architectural and building structures in the form of smooth and composite surfaces have become relevant and in demand lately, which determined the purpose of this article - to analyze the use of analytical surfaces given vector, parametric or explicit equations in real structures. Methods. The relationship between studies on the geometry of surfaces of revolution and transport and the creation of new forms of thin-walled structures and buildings is determined. An example of a real structure is given on each surface. The article does not consider composite, multifaceted, fractal surfaces, as well as surfaces that are not defined analytically. Results. It turned out that only a small number of considered surfaces of these two classes have found application in the world. At the end of the article, a bibliography is presented, which sets out the mathematical side of the design of analytical surfaces, their computer modeling, more detailed information about real structures in the form of the surfaces under consideration.

Relevance. The problems of decline of resource-demanding of objects of building and engineer dictate the necessity of consideration of processes of deformation of constructions at the resiliently-plastic state. The widely in-use theory of account of practical properties of material is a deformation theory of plasticity. The aim of the research is development of variants of receipt of determining correlations on the step of ladening at deformation of material outside a resiliency. Methods. Algorithms over of receipt of determining correlations of theory of small resiliently-plastic deformations are brought on the step of ladening in two variants. In the first they turn out differentiation of expressions of tensions as functions of deformations on the basis of deformation theory of plasticity; in the second determining correlations turn out on the basis of hypothesis about the proportion of components of deviators increases of tensions to components of deviators increases of deformations. Results. On the test example of calculation of the jammed cylindrical shell realization of the got determining correlations is presented.

Relevance of the research is due to the fact that over the past 10 years severe accidents at large hydropower plants and dams occurred in Russia (SayanoShushenskaya HPP, 2009), USA (Oroville dam, 2018), Brazil (Brumadinho dike, 2019), Colombia (HPP Ituango, 2018) and other countries, the need has arisen to improve the safety programs of the HS and dams. The main method of this important work is to use methods of analysis and assessment of risk accidents of HS and dams. Methods of this important work are to develop modern methodology for analyzing and assessing the risk of accidents of HS and dams. The introduction of the method of analysis and risk assessment in the safety programs of hydraulic structures (dams) in countries that are advanced in the construction of HS (China, Brazil, Canada, USA, Russia, Colombia, Norway, Spain, etc.) shows that in applying risk assessment analysis accidents of HS and dams still a number of difficulties, but this approach is of great benefit in monitoring the safety of HS and dams. The aim of this article is to familiarize and train specialists and hydraulic engineers with modern methods for assessing the safety of HS and dams.