Vol 18, No 3 (2022)

Analysis and design of building structures

Survivability of reinforced concrete frames of multi-storey buildings with complex stress elements

Kolchunov V.I., Moskovtseva V.S.


Experimental determination of the parameters of the force resistance of reinforced concrete structures aimed at protecting them from emergency beyond design impacts is an important direction in improving the safety of buildings and structures. In this connection, the purpose of the study was an experimental assessment of the deformation parameters in the complexly stressed elements of reinforced concrete frames under special impact in the form of a sudden column removal. Experimental studies were carried out for two frames, one of which was tested when removing the middle column, the second - when removing the extreme. Experimental two-span structures of reinforced concrete frames are designed with three floors in height, reinforcement was made with spatial reinforcing cages that provide resistance to torsion with bending. The results of experimental and theoretical studies of reinforced concrete frame structures under special influences and an assessment of displacements, cracking and destruction of the considered complex-stressed structural elements under such influences are presented. It is established that the type of stress state, the formation and width of crack opening significantly affect the dissipative properties of the structural system.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(3):195-203
pages 195-203 views

Rigidity, adhesion and delamination of the coating in the “substrate - coating” system

Yakupov S.N., Gubaidullin R.I.


Protective coatings are widely used in all branches of production and life. The necessary qualities of coatings are provided by developing complex thin-layer compositions. The complexity of the structure of the coating also arises during operation as a result of the influence of the environment, physical fields, human factor. Many coatings are initially formed directly on the surfaces of structures with initially complex geometry. At the same time, a number of smart coatings, along with a complex structure, change their physical and mechanical properties when triggered. When choosing a coating, adhesive and technology for its application, questions arise related to determining their necessary geometric and physical parameters, assessing their mechanical properties and service life depending on the environment and physical fields, etc. This requires a reliable research tool. In the review, based on well-known publications and patents for the invention, the following are noted: methods for studying the mechanical properties of decomposable and non-decomposable coatings; methods for determining adhesion - the adhesion strength of the coating to the substrate; methods for studying the delamination of constituent elements and delamination of the coating from the substrate. Attention is focused on effective experimental and theoretical methods for assessing the mechanical properties of the coating and adhesive on flat and non-planar surfaces, as well as on some relevant results.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(3):204-214
pages 204-214 views

Analysis for the efficiency of additional dispersed reinforcement using coconut fiber for a concrete beam with traditional steel bar reinforcement

Chongo P., Shambina S.L., Tembo O.


Concrete is widely used as a building material throughout the world. However, its use in building structures is limited due to its low tensile strength. This problem can be partially solved using steel bars reinforcement, as well as using dispersed reinforcement with various types of fibers. The authors propose the simultaneous traditional reinforcement of a concrete structure with steel bars with additional dispersed reinforcement with natural coconut fibers, relatively cheap and widely available in many countries in Africa, Asia and Latin America. The purpose of this study is to analyze the effectiveness of the proposed solution by comparing the required amount of steel reinforcement (by weight) for a beam made of traditional concrete and a similar beam with additional dispersed reinforcement with coconut fibers. Deflections and cracking in beams were investigated. The analysis was carried out using Autodesk Robot Structural Analysis Professional 2022 software. The results showed that a beam additionally reinforced with coconut fiber requires 11% less steel reinforcement (by weight) compared to a similar beam made of traditional reinforced concrete. In addition, the coconut fiber reinforced beam experienced 6% less deflection and significantly less stress cracking compared to a simple concrete beam. These results proved that the approach proposed in the work noticeably improves the performance of reinforced concrete in the structure, and also makes it possible to obtain significant savings in reinforcing steel.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(3):215-227
pages 215-227 views

Analytical and numerical methods of analysis of structures

Volumetric element with vector approximation of the desired values for nonlinear calculation of the shell of rotation

Gureeva N.A., Kiseleva R.Z., Kiselev A.P., Nikolaev A.P., Klochkov Y.V.


The usage of traditional approximating functions directly to the desired displacement vector of the internal point of a finite element to determine it through nodal unknowns in the form of displacement vectors and their derivatives is described. To analyze the stress state of a geometrically non-linearly deformable shell of rotation at the loading step, the developed algorithm for forming the stiffness matrix of a hexagonal finite element with nodal values in the form of displacement increments and their derivatives was used. To obtain the desired approximating expressions, the traditional interpolation theory is used, which, when calculated in a curved coordinate system, is applied to the displacement vector of the internal point of a finite element for its approximation of class C(1) through nodal displacement vectors and their derivatives. For the coordinate transformation, expressions of the bases of nodal points are obtained in terms of the basis vectors of the inner point of the finite element. After the coordinate transformations, approximating expressions of class C(1) are found for the components of the displacement vector of the internal point of the finite element, leading in a curved coordinate system to implicitly account for the displacement of the finite element as a rigid whole. Using calculation examples, the results of the developed method of approximation of the required values of the FEM with significant displacements of the structure as an absolute solid are obtained.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(3):228-241
pages 228-241 views

Comparative study of finite element methods of calculation of ribbed reinforced concrete floors

Nikitin K.E., Kirsanov O.A.


The paper presents the results of a comparative study of several finite element models of ribbed reinforced concrete solid floors. Using the example of a solid slab with infrequent ribs arranged along a grid of columns, three models frequently used in computational practice are analyzed. Those models include both rods and thin-walled elements. In the first model, the plate and its ribs are considered separately, within the framework of the decomposition scheme of the structure. The second model contains plate finite elements and the rod finite elements of the ribs connected to each other. The third model consists entirely of thin-walled finite elements that model both the plate and the floor ribs. The ribbed floor is also considered in the formulation of the problem within the framework of the theory of elasticity. The floor is represented in the form of rigidly connected solid bodies of ribs and plates. Reinforcement rods inside the concrete massive are included in the model as separate solid bodies. This model serves as a benchmark for assessing the accuracy of the obtained results. Its calculation is performed in the FEM application Ansys. The paper compares the results of calculations performed using various models. A conclusion is made about the accuracy of the obtained results. A significant difference between the proposed work and similar studies devoted to the selection of the best design schemes of ribbed slab of floor is the consideration of the influence of reinforcement on the behavior of the structure.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(3):242-254
pages 242-254 views

Theory of Thin Elastic Shells

On the basic architectural styles, directions, and style flows for shells and shell structures

Krivoshapko S.N.


It was ascertained that investigations on classification of architectural styles for shells and shell structures are absent. Only one published paper is available where architectural styles with indication of dates of appearance of the styles and dates of attenuation of their application are presented and the names of their founders are given. Now, the interest for the design, analysis, and building of thin-walled shells and shell structures is rising. There are no countries without erected shell structures. Hence, it is necessary to make more exact the classification of these erections and the distribution of them into groups. An aim of this work is collection of information about all known architectural styles as applied to shells and shell structures, and grouping of them due to characteristic traits and indications. All architectural styles were divided into five groups, i.e. avant-gardism, art deco style, modernism, ecotech style, and the newest styles. A special scheme, where distribution of architectural styles on these groups is applied to the examined structures, is given. Mutual influence of styles was revealed and presence of architectural directions and style flows in several styles was shown. The conclusions presented in this paper can demand the future accurate definitions and developments because specialists do not have common views to the list of architectural styles and to their classifications.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(3):255-268
pages 255-268 views

Dynamics of structures and buildings

Investigation of waves in the strengthened net

Agalarov J.H., Mammadova G.A., Rustamova M.A.


The movements of a reinforced net are considered. Mesh systems are used in various areas of modern technology, aviation, fishing, and construction. In recent years, much attention has been drawn to the complete equations that describe the motion of a deformable thread. In accordance with the studied task, the reinforcement of the net is carried out by adding terms in the equations of motion. In the planar case, the static behavior of the structure is investigated, and equations of motion are derived that allow the study of motion. The problem of wave propagation in deformable filament systems, taking into account a significant deviation of the filament shape from the original rectilinear one, is mathematically very difficult, since the equations of motion are a system of nonlinear differential equations in partial derivatives. To solve the problem, the method of characteristics is used. As well the method of characteristics solves the problem of the propagation of unloading waves (in the case of a load, shock waves arise). Depending on the velocity distribution at the boundary, the distribution of the strain constant on the characteristics is determined. The results are constructed by numerical integration of the integrals of the characteristics found by the method. The solution using the characteristic equations shows the occurrence of traveling waves.

Structural Mechanics of Engineering Constructions and Buildings. 2022;18(3):269-279
pages 269-279 views

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