Vol 19, No 1 (2023)

Analysis and design of building structures

Calculation of the formation of normal cracks in a reinforced concrete element based on the deformation theory of plasticity of concrete by G.A. Geniev

Vu N.T., Fedorova N.V.


The authors present a refined method of determining the moment of cracking in reinforced concrete bar constructions using the diagram of deformation of concrete built on the basis of the deformation theory of plasticity by G.A. Geniev in which the stress and strain invariants of concrete are linked by nonlinear dependences. In the resulting defining equations, the hypothesis of flat sections, as well as the premise of reaching the limit values of concrete deformations on the stretched fibers of the cross-section are used. Stresses in concrete are determined through deformation values in accordance with the nonlinear deformation diagram of concrete. On the basis of the assumptions accepted, analytical dependences for determining the moment of cracking in the sections of bending elements with single and double reinforcement have been acquired. The formulas obtained were used in the analysis of various factors influence on crack resistance of bendable reinforced concrete elements. It was found out that the moment of crack formation practically does not change when percentage of reinforcement of longitudinal tensile or compressed reinforcement changes. The most effective method of crack resistance improvement is the increase of concrete strength. The proposed methodology is verified by comparison with experimental results on reinforced concrete prototypes. It is concluded that the use of the diagram of nonlinear deformation of concrete on the basis of the theory of plasticity by G.A. Geniev allows to estimate more strictly the crack resistance of reinforced concrete rod elements.

Structural Mechanics of Engineering Constructions and Buildings. 2023;19(1):3-16
pages 3-16 views

Modal analysis of a large-span building with different boundary conditions

Kuzhakhmetova E.R., Sutyrin V.I.


The authors present the results of a modal analysis of finite element models of a large-span building with a cylindrical-and-slab roof as a large mechanical system. During the numerical study, the following spatial models are considered: 1) superstructure - fixed-end; 2) superstructure - pile foundation - soil base. The purpose of the study is to compare the results of a modal analysis of the design of a large-span building with different boundary conditions, physical and mechanical properties of the soil base. Modal analysis of a large-span building with a cylindrical-and-slab roof was carried out using the Femap NX Nastran CAE-class software package implementing the finite element method. The authors compare the frequencies and modes of natural oscillations of the construction of spatial models obtained on models of types 1 and 2 of the large-span building with a cylindrical-and-slab roof. As a result of the modal analysis of model 2, the influence of the physical and mechanical properties of the soil base on the characteristics of the structure's own oscillation was revealed. In the prospect, it is proposed to conduct a dynamic analysis of a large-span building with a cylindrical-and-slab roof for seismic effects.

Structural Mechanics of Engineering Constructions and Buildings. 2023;19(1):17-34
pages 17-34 views

Theoretical basis for the development of a program for the evaluation of road bridge heavy vehicles capacity

Lugovtsev E.A., Utaliev K.N., Chutkov K.A.


The authors present theoretical basis for creating software for operational (on-site testing) experimental determination of the possibility of safe passage of heavy vehicles on road bridges, taking into account their actual operational condition with experimental confirmations. The features, conditions of use, and benefits of the software under development are expanded upon. The creation of the software is driven, on the one hand, by the need to ensure the safety of the driver and the bridge structure, and on the other hand, the need to assess the load capacity of the superstructures of road bridges according to the parameters of their stress-strain state to ensure guaranteed safe passage of heavy vehicles. The developed software for the operational determination of the possibility of safe passage of heavy vehicles on road bridge structures, with the consideration of their actual operational condition, is implemented using a personal computer. The software provides an assessment of the possibility of heavy vehicle passage through split and non-split systems of any length, considering the actual operational condition of the systems, while allowing to safely use any mobile load as a point of reference. The introduced software will be used as part of an upgraded system for rapid assessment of the load capacity of road bridges, developed on the basis of the SI-PPM measurement system with the addition of technical devices that increase the possibility of operational assessment of the load capacity of road bridges.

Structural Mechanics of Engineering Constructions and Buildings. 2023;19(1):35-45
pages 35-45 views

Evaluation of a reliability index for steel trusses to the deflection criterion with interval uncertainty of data

Solovev S.A., Inkov A.E., Soloveva A.A.


The authors describe a new approach to evaluation the reliability index of steel trusses by the criterion of deflection considering the uncertainty of random variables expressed in the interval form. Classical probabilistic-statistical methods of structural reliability analysis require the choice and justification of the cumulative distribution functions for random variables and its parameters. Subjective acceptance of statistical hypotheses can lead to large errors in the structural reliability analysis. In this study, it is proposed to represent random variables in the interval form that characterize the boundaries of their variability. Such intervals can be obtained as tolerances by the technical documentation, can be based on the construction experience or can be got by data analyzing. The Vysochansky - Petunin inequality is used to obtain the limits of variability of a random variable without a hypothesis about a specific probability distribution function. The reliability analysis of bar-systems is complicated due to the uncertainty of the data in each element of the system. For the engineering solution of this problem, an analytical approach to the optimization problem is offered. The truss reliability index can be used to compare several design solutions in a quantitative form according to the criterion of operational safety.

Structural Mechanics of Engineering Constructions and Buildings. 2023;19(1):46-55
pages 46-55 views

Analytical and numerical methods of analysis of structures

Calculation of radially inhomogeneous ring loaded with normal and tangential loads

Andreev V.I.


The aim of the study is to solve the problem of the stress-strain state of a thin ring under radial and ring loads, factoring in the radial inhomogeneity of the ring. Also, the task is to compare the two calculation methods to the example of solving the problem of uneven load distribution along the outer surface of the ring with one-dimensional inhomogenuity. Analytical or numerical-analytical solutions are used in the two-dimensional plane problem of the theory of elasticity in polar coordinates for an inhomogeneous body. Most of these problems consider centrally symmetric circular bodies. As a rule, this is possible when all unknown functions depend on the radius. These tasks correspond with the majority of ring and cylindrical structures. Pipes are suitable for creating pipeline systems and civil engineering, they are used for gas pipelines, in heating networks and water supply systems. The key feature of the work lies in the consideration of uneven radial and ring loads distribution along the outer surface of the ring. Comparison of the calculation results obtained by two methods makes it possible to determine the stressed and deformed states with sufficient accuracy, an indicator of which is the obtaining of the ring stresses.

Structural Mechanics of Engineering Constructions and Buildings. 2023;19(1):56-63
pages 56-63 views

Quadrilateral element in mixed FEM for analysis of thin shells of revolution

Klochkov Y.V., Pshenichkina V.A., Nikolaev A.P., Vakhnina O.V., Klochkov M.Y.


The purpose of study is to develop an algorithm for the analysis of thin shells of revolution based on the hybrid formulation of finite element method in two dimensions using a quadrilateral fragment of the middle surface as a discretization element. Nodal axial forces and moments, as well as components of the nodal displacement vector were selected as unknown variables. The number of unknowns in each node of the four-node discretization element reaches nine: six force variables and three kinematic variables. To obtain the flexibility matrix and the nodal forces vector, a modified Reissner functional was used, in which the total specific work of stresses is represented by the specific work of membrane forces and bending moments of the middle surface on its membrane and bending strains, and the specific additional work is determined by the specific work of membrane forces and bending moments of the middle surface. Bilinear shape functions of local coordinates were used as approximating expressions for both force and displacement unknowns. The dimensions of the flexibility matrix of the four-node discretization element were found to be 36×36. The solution of benchmark problem of analyzing a truncated ellipsoid of revolution loaded with internal pressure showed sufficient accuracy in calculating the strength parameters of the studied shell.

Structural Mechanics of Engineering Constructions and Buildings. 2023;19(1):64-72
pages 64-72 views

Statics and dynamics of curved rods based on Bernoulli hypotheses and relations for a rectilinear rod

Serazutdinov M.N.


Method for calculating the statics and dynamics of curved rods, based on the equations for a rectilinear rod, is described and justified in detail. Bernoulli's hypotheses and the variational method are applied. The main advantage and special feature of these formulas is that the simplest formulas that are valid for rectilinear rods are used for the calculations of curved rods. These formulas do not contain parameters characterizing the curvatures of the longitudinal axis of the rod. This feature is an essential factor in the calculation of curved rods, where the information about their longitudinal axis is given discretely, since no special methods of approximation of discretely given data are required, which enable to obtain information about the radius-vector of the rod longitudinal axis and its derivatives with the required high accuracy. Solutions of test static and dynamic problems are provided. Bending of a rod with a longitudinal axis in the form of a circle, a naturally twisted rod, and a spring fluctuation are considered. Comparison of the calculation results with the data published in the literature illustrates the reliability and high accuracy of the solutions obtained.

Structural Mechanics of Engineering Constructions and Buildings. 2023;19(1):73-83
pages 73-83 views

Geometrical investigations of middle surfaces of shells

Geometry and static analysis of thin shells in the form of a diagonal translation surface of the velaroidal type

Aleshina O.O.


The author presents the results of a study of the geometry and stress-strain state of a surface with a frame of three flat curves in coordinate planes, which have found application today mainly in the shipbuilding industry. The purpose of the work is to identify from the point of view of the stress-strain state from the action of a constant uniformly distributed load the most optimal shell of a diagonal transfer of a velaroidal type with the same main frame of three superellipses. The static calculation was performed using the SCAD program based on the finite element method, designed to perform strength calculations of various types and purposes of structures. The influence of parametric equations for defining a surface depending on the generative family of the same type of cross sections on the distribution pattern of normal stresses and bending moments is shown. The results obtained can help architects and designers with choosing the shape of shells for new projects.

Structural Mechanics of Engineering Constructions and Buildings. 2023;19(1):84-93
pages 84-93 views

Hydraulic constructions

Safety assessment of massive buttress dams in the presence of thermal cracks in them

Zimnyukov V.A., Zborovskaya M.I.


In the 1950s, the construction of hydropower facilities began in the regions of Siberia and the Far East, characterized by harsh climatic conditions, which should be taking into account to predict the stress state of dams. The aim of the study is an assessment of the conditions for the formation of temperature cracks in concrete dams and their influence on the further operation of the structure, as well as measures and technologies to combat cracking in massive concrete. Thermal stresses often exceed the stresses caused by the action of external loads and lead to the appearance of cracks in the concrete. Almost all modern concrete dams are subject to thermal cracking today. Appropriate design and technological measures must be provided for. When studying the thermally stressed state of lightweight concrete dams, the method of direct reproduction of thermal deformations on models made of brittle materials and computational methods oriented towards computer methods of solving problems are used. The results of modeling and computational studies of massive buttress dams are presented and the influence of the main influencing factors is considered, taking into account the effect of cracking on the operation of such dams.

Structural Mechanics of Engineering Constructions and Buildings. 2023;19(1):94-109
pages 94-109 views

Estimation of the main parameters of wave action on the gentle slopes of the banks of large water bodies

Chernykh O.N., Burlachenko A.V.


When designing coastal protection measures, special attention is paid to the creation and expansion of a natural beach slope on the coast of a water body. To assign geometric dimensions to relatively stable beach slopes, it is necessary to evaluate the relationship of waves, taking into account the level regime characteristic of a given section of the coast. The aim of the research is to explore the features of the transformation of the wave profile in shallow water and to conduct a comparative analysis of theory and experiment. The studies were carried out in a wave tray, where the waves were reproduced by a swinging shield. The features of the transformation of the wave profile at decreasing depths of the shallow water of a large water body are considered. An assessment is given of the change in the kinematic characteristics of a wave incident in a shallow water zone on an unfortified beach slope with a depth of 10, 20 and 30. The results of experimental studies are presented and analyzed, as a result of which the influence of the wave steepness on the kinematic characteristics and features of wave transformation in shallow water is revealed. A comparative analysis of theoretical solutions and experimental data with an assessment of the area of their applicability is carried out. On the whole, the wave profile and the horizontal component of the orbital velocity during the passage of the wave crest are in satisfactory agreement with the calculations according to the Stokes theory at relative depths of more than 0.07. It has been established that for shallow water conditions the relative height of the wave crest affecting the beach slope of the near-shore zone of the coast of a large water body is most noticeably affected by the slope, with an increase from 10 to 30 the magnitude of the wave steepness can increase by 1.2 times.

Structural Mechanics of Engineering Constructions and Buildings. 2023;19(1):110-116
pages 110-116 views

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