Vol 15, No 3 (2019)

Analysis and design of building structures
Method of full discretization in joint calculation in time of the system “construction - foundation - soil”
Ter-Emmanuilyan T.N., Polumordvinov I.O.

Introduction. Prospective transition of CIS to the European design standards in the construction industry requires development of new and modification of known engineering methods for calculation and design of construction. Creation and development of such methods should be based on fundamental research that can become the basis for the development of principally new, innovative technologies. Methods. The paper consists of basis and practical application of the method of full discretization. This method is a special modification of finite element method for the solving of problems of the creep. Practical application of the method is illustrated with modeling and applied tasks. Results. The paper presents a joint calculation of the “structure - foundation - soil” system using the example of a reservoir of a modular biological wastewater treatment plant designed for filtration fields in the village of Tasboget, Akmola region, the Republic of Kazakhstan. The full picture of the evolution of the stress-strain state of structures is gained, taking into account the material creep and the history of construction. There is a comparison of result calculations with and without technology of erection of structures.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(3):171-181
Rationalization of the constructive form of towers with prestressed cables
Sitnikov I.R., Golikov A.V.

Relevance. One of the main directions of development of mobile communication systems, radio engineering and telecommunication systems is the improvement of the structural form of the bearing supports, which will solve a number of practical tasks: to increase the coverage area, to ensure higher rates of data transmission speed and to ensure stable operation in an increasing number of users. These circumstances justify the relevance of research in this direction. Aims of research. Optimization of design solutions using parallel puffs, ensuring the possibility of erection and safe operation during the entire service life, which ensures that the requirements for strength, stability and deformations for such structures are met with minimal material consumption. Methods. For calculations, finite element methods are used for mathematical modeling using software and computing systems. To create linear models for numerical experiments, the method of mathematical planning of experiments was used. Results. The work of the towers of the proposed constructive solution is considered as supports for the placement of equipment of cellular operators using the example of a 42-meter tower. The method of mathematical planning of experiments was used to create a model line for numerical experiments. To establish the basic characteristics of the stress-strain state of the structures of the supports, a number of models were created and calculated in software packages, the basis of which is the finite element method. A comparative analysis of the effort in the delays determined by analytical calculation and the finite element method is performed. The analysis of changes in the stress-strain state of the towers from the influence of influencing factors, such as wind and icy-wind loads, the angle of deflection on the lower tier of the tower. By the criterion of minimum metal consumption and manufacturability of the construction of towers, rational overall dimensions of the tower were determined. The options for constructing the main junctions of the elements of the tower are proposed.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(3):182-192
The results of computer analysis of the wind load acting on the set of rolled profiles
Veselev Y.A., Karabutov M.S.

The aim of the research is to numerically determine the effect of wind loads on the roof of the rolled profiles of the MIC-120 system. Methods. There were made some calculations in this article of wind load, acting on rolled metal thin-sheet profiles arch and a comparison of computer modeling and buildings requirement such as Building Rules “Loads and Actions” results. The research was carried out by means of modeling of a virtual wind tunnel with the placement to it a metal thin-sheet profiles arch in consideration of different wind actions such as acting on the arch’s butt end (along a generatrix), as well as athwart on the arch and angularly on it with the arch’s width change from 12 to 24 m. The arch modeling as well as the virtual wind tunnel modeling was based on the COSMOSFloWorks software package by means of the method, stated in the previous publications [2; 11]. The theoretical and methodological basis of the research is the Navier - Stokes equation and the equation of the condition of the fluid medium’s components. Results. The results are, first of all, the calculation of the wind pressure on the arch depending on the trajectory, wind speed in different regions and directions of wind flow, secondly, the comparison of the wind pressure, getting with the help of computer modeling with Building Rules 20.13330.2011 “Loads and Actions” and, finally, matching of results of wind pressure for a plain and ribbed arch with equal geometrical parameters, getting by computer modeling. In compliance with the generated calculations there was drawn a conclusion, that the standard pressure according on Building Rules does not change from arch span, but results of the computer modeling show us a change of the wind pressure from the arch’s span.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(3):193-200
Theory of thin elastic shells
Optimal shells of revolution and main optimizations
Krivoshapko S.N.

Introduction. Optimization is a criterion, on the ground of which, comparative estimation of possible alternatives and selection of the best decisions is carried out. Cost of a shell, its minimum weight, absence of bending moments and tensile normal stresses, given stress state for acting external load, given bearing capacity when optimal shallowness, maximum external load, minimum weight under limitation on the value of natural frequencies of vibration and maximum displacements, absence of bending moments with taking into account internal pressure, dead weight, and centrifugal forces; maximum of critical force and something else can be criterion of selection of optimal shape of shell of revolution. Methods. The main criteria of optimality for shells of revolution and information sources for the 1970-2019 periods are presented in a paper. It will help to study previous results devoted to using optimizations and to set about further investigation. But there is no single approach to the definition of optimal shell of revolution and obviously will not be, because own optimizations are necessary for every concrete case of loading, or distribution of stresses along the thickness, or under the demands to the ratio of the volume and area of considered shell, or with due regard for different kind of expenses, and other demands. Results. For the first time, 24 criteria of optimality only for shells of revolution were discovered. The names of scientists offered presented criteria of optimality and the 45 references dealing with this question are pointed out. It is shown that principles put in the basis of optimal design and criteria of optimality must be given with the help of language quite naturally for computer. Having used optimi- For citation Krivoshapko S.N. (2019). Optimal shells of revolution and main optimizations. Structural Mechanics of Engineering Constructions and Buildings, 15 (3), 201-209. http://dx.doi.org/ 10.22363/1815-5235-2019-15-3-201-209 zations presented in the paper, designers can choose the criterion for their own design of optimal shell shape. Study of the prerequisites of the structural solutions in building and machine-building, the history of the development and perfecting of technologies of erection of shells of revolution will permit to generalize the experience accumulated by designers and to develop new fundamental solutions. Otherwise, architects, structural engineers, and designers will be repeating the achieved solutions in building, architecture, and machine-building.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(3):201-209
Geometric modelling and materially nonlinear numerical analysis of shells in the shape of one-sheet hyperboloid of revolution
Giloulbé M., Jazzan M., Qbaily J.

Aims of research. A surface of revolution is generated by rotation of a plane curve z = f(x) about an axis Oz called the axis of rotation. This paper provides information on hyperboloids of revolution surfaces and their classification. Their geometric modeling, linear and materially nonlinear analysis are worked out. Methods. Hyperboloids of revolution middle surface is plotted using the software MathCAD. The linear and materially nonlinear numerical analyses of thin shells of the shape of an hyperboloid of revolution surfaces on stress-strain state is given in this paper, using the finite elements method in a computer software R-FEM, the material which we use in our model is concrete with isotopic nonlinear 2D/3D stress-strain curve for materially nonlinear analysis and linear stress-strain curve for linear analyses. Comparison is done with the result of the finite elements linear analysis of their strain-stress results. Results. That displacements in the investigated shells subject to self-weight, wind load with materially nonlinear analysis are bigger than which done by linear analysis, in the other side the displacements is similarity subjected to free vibration load case. Based on these results, conclusions are made for the whole paper.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(3):210-218
Dynamics of structures and buildings
Risk assessment for seismic and fire hazards at hazardous industrial and classified sites industry
Suleymanov A.A., Djuraev O.A., Umarov F.Y., Shomansurov S.S.

Aims of research. Research and analysis assessing the risk of hazards (in particular earthquake hazardous) at hazardous industrial and classified sites industry. Methods: analytical, mathematical, operational-tactical, mechanical-statistical, study of deformation of seismic diaphragms. The analysis of risk through seismologist at hazardous production facilities of the industry in conjunction with the secondary fires. This circumstance, which often coincides with the joint vector, is proposed to be used as a mechanism to ensure the safety of industrial facilities from seismic fire hazard, including aspiration flows as an impact factor. Risk analysis is viewed taking into account the algorithm to ensure the safety of complex technical and social systems, which shows the degree of universality of the algorithm. This security mechanism is most important to take into account for architectural General plans of buildings and structures, as well as in operational and tactical actions of units in the aftermath of emergencies, crisis and extreme events. Results. The analysis is accompanied by the necessary mathematical calculations and experimental assessments of the security process.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(3):219-228
Calculation of foundation vertical stiffness with the piles mutual influence effect
Kolesnikov A.O., Kostiuk T.N., Popov V.N.

Aims of research. Studies to determine the effect of the distance between the piles in group with vertical oscillations of pile foundations on the value of dynamic stiffness are carried out and the results obtained in full-scale tests, within the wave model and according to SP 26.13330.2012 are compared. Methods. The eigenfrequency changes of the foundation of nine piles with a diameter ( d ) with a high pile cap are calculated depending on the distances between the piles - 2 d , 3 d and 5 d . The obtained results are compared with the data obtained after a series of pulse dynamic loads performed under semi-natural conditions on foundation models. The values of the transverse wave velocities were determined directly at the test site. Results. It is found that the reduction of the distance between the piles in the bush leads to a decrease in the natural vibration frequencies of pile foundations. Reducing the distance between piles from 5 to 2 diameters of piles leads to reduce the frequency of vertical vibrations of pile foundations by 1. times. It is shown the advantage of the results of calculations in the frame-work of the wave model in comparison with the method of SP 26.13330.2012. Also shown their high coincidence with the values obtained in the course of experiments, which allows to accurately determine the amplitude-frequency characteristics of the foundations. The results determined according to SP 26.13330.2012 have significantly lower values of natural frequencies and do not fully reflect the change in the distance between the piles. The maximum discrepancy with the experimental data is 2.7 times for the vertical oscillations of the pile foundation.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(3):229-236
Experimental researches
Experimental studies of reinforced concrete structures of hydraulic structures strengthened with composite materials
Frolov K.E.

Relevance. During the operation process (first of all, long-term operation) of hydraulic structures, it becomes necessary to strengthen their reinforced concrete structures. In recent years, reinforcement of reinforced concrete structures has been used in industrial and civil construction by external reinforcement systems made of composite materials (for example, carbon materials). In this case, in hydraulic engineering construction there are only isolated examples of such amplification. Aims of research. Experimental studies of reinforced concrete structures of hydraulic structures strengthened with external reinforcement from carbon materials presented in the article were carried out in order to substantiate the use of external reinforcement based on carbon materials (tapes and lamellae) to reinforce reinforced concrete structures of hydraulic structures. Methods. In order to carry out an experimental study of the strengthening of hydraulic structures with external reinforcement, reinforced concrete models of hydraulic structures of a beam type were made of carbon materials. At the same time, reinforced concrete structures with characteristic features of hydraulic structures, such as low concrete classes and reinforcement percentages (less than 1%), were adopted for modeling. Reinforced concrete models were strengthened with carbon ribbons and lamellae. Experimental studies were carried out under the action of a bending moment using standard methods. The increase in the strength of reinforced concrete structures due to their reinforcement with carbon ribbons and lamellae was determined. Results. The results of experimental studies of the strength of reinforced concrete structures of hydraulic structures without reinforcement and reinforced with carbon ribbons and lamellae under the action of a bending moment are presented. On the basis of the comparison carried out, the increase in the strength of reinforced concrete structures is determined by their reinforcement with carbon ribbons and lamellae.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(3):237-242
Determination of destructive forces in a rod-cable arch
Dmitriev I.K.

The aim of research - comparison the results of the experimental data with the computer modeling the work of the strengthened brick-cable arch. Methods. Experimental and theoretical methods of research. Results. Firstly, the tests on a small desktop models were performed, for the determination the nature of destruction of the construction. During them, it was discovered, that the arch crash is taking place because of the splitting the small size timber bricks, or as the result of the breaking its steel strengthening elements. Further, the computer model of the construction was created with the help of physically and geometrically nonlinear finite elements at LIRA-SAPR PC. The generated model was load by a concentrated force at its top zone, the same one, as it had been during the experiments before. On the results of the calculation, the maximum deformation was received, which are different from the experimental one on a value less then 10%, what suggests the nearness the computer model to the real construction. The highest compressive strengths of the arch and the largest stretching forces of its steel bands were determined during the further analysis of the model. Maximum splitting and stretching forces also were calculated theoretically, according to the formulas of SP 64.13330.2017 and SP 20.13330.2016. It was determined that the timber bricks have more than 7 times reserve of strength, and the steel bands over them - only times, and during the growth of external force, the arch will crash because of its steel sprengel bands breakage. By the results of the research, the calculation algorithm of such kind constructions was generated, at the base of LIRA-SAPR PC. It was recommended first, to determine deformation of the strengthened brick-cable arch, with further checking the timber elements for splitting and steel sprengel elements for maximum permissible stretching. The problem of stability the flat form of deformation for the brickcable arch are the same as for the glued one, because of the tight connection the timber bricks, with elimination their exit from the frontal plane.

Structural Mechanics of Engineering Constructions and Buildings. 2019;15(3):243-248

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