Pub Date : 2022-07-20DOI: 10.22363/1815-5235-2022-18-2-111-139
A. Marutyan
The article presents a continuation of the optimization of channel and I-shaped bended closed profiles (BCP) with tubular flanges and perforated walls made of rolled sheet products of both equal and different thicknesses. Such profiles are designed for light steel thin-walled structures (LSWS), which are distinguished by improved technical and economic indicators and mass demand in industrial and civil construction, which confirms the relevance of their further development. The purpose of the study is to show that the characteristics of LSWS can be further improved by shaping profiles, combining straight and round outlines of closed and open contours in a composite section, including their perforation. Through experimental design studies, solving optimization problems and variant design of the BCP, their design sections with a maximum margin of bending strength with a minimum mass have been refined. The originality of technical solutions is confirmed by patent examination. The channel BCP has extreme weight and strength with a relative height of cutouts in the wall of 1/1.87 and a ratio of width and height dimensions of 1/4.32. When the thickness of the shelves is 2 times the wall thickness, the strength and mass of the I-shaped BCP are extreme at a relative height of cutouts of 1/1.23 and a ratio of dimensions of 1/4.17, and when the thickness of the shelves is 0.6 of the wall thickness, the strength and mass of the BCP are extreme with a cutout height of 1/1.73 and a size ratio of 1/5.22. If the thicknesses of the shelves and the wall are equal, then the strength and mass of the BCP is extreme at a cutout height of 1/1.46 and a size ratio of 1/3.17.
{"title":"Optimization of channels and I-shaped bended closed profiles with perforated walls","authors":"A. Marutyan","doi":"10.22363/1815-5235-2022-18-2-111-139","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-2-111-139","url":null,"abstract":"The article presents a continuation of the optimization of channel and I-shaped bended closed profiles (BCP) with tubular flanges and perforated walls made of rolled sheet products of both equal and different thicknesses. Such profiles are designed for light steel thin-walled structures (LSWS), which are distinguished by improved technical and economic indicators and mass demand in industrial and civil construction, which confirms the relevance of their further development. The purpose of the study is to show that the characteristics of LSWS can be further improved by shaping profiles, combining straight and round outlines of closed and open contours in a composite section, including their perforation. Through experimental design studies, solving optimization problems and variant design of the BCP, their design sections with a maximum margin of bending strength with a minimum mass have been refined. The originality of technical solutions is confirmed by patent examination. The channel BCP has extreme weight and strength with a relative height of cutouts in the wall of 1/1.87 and a ratio of width and height dimensions of 1/4.32. When the thickness of the shelves is 2 times the wall thickness, the strength and mass of the I-shaped BCP are extreme at a relative height of cutouts of 1/1.23 and a ratio of dimensions of 1/4.17, and when the thickness of the shelves is 0.6 of the wall thickness, the strength and mass of the BCP are extreme with a cutout height of 1/1.73 and a size ratio of 1/5.22. If the thicknesses of the shelves and the wall are equal, then the strength and mass of the BCP is extreme at a cutout height of 1/1.46 and a size ratio of 1/3.17.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47612866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-20DOI: 10.22363/1815-5235-2022-18-2-140-149
S. Krivoshapko, M. Giloulbé
A class of developable surfaces contains cylindrical, conical, and tangential developable surfaces. Tangential developable surfaces are ruled surfaces of zero Gaussian curvature with cuspidal edges. They give great opportunities to architects and engineers for realization of their creative projects. Both the theoretical researches in the area of geometry of torses and strength analysis of shells and the influence of these researches on the application of torses in practice are shown. A presented research demonstrated that torses found the application in shipbuilding, aircraft construction, mechanical engineering, in architecture and building, engineering equipment and communications, in road building, in anti-erosive banks, topography, and cartography, clothing articles of light industry, in sculptural forms, and in modelling with developable surfaces. It was confirmed by the references on great number of published works on the subject, real examples from practice, and by handing in 14 illustrations of real objects.
{"title":"Tangential developable surfaces and their application in real structures","authors":"S. Krivoshapko, M. Giloulbé","doi":"10.22363/1815-5235-2022-18-2-140-149","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-2-140-149","url":null,"abstract":"A class of developable surfaces contains cylindrical, conical, and tangential developable surfaces. Tangential developable surfaces are ruled surfaces of zero Gaussian curvature with cuspidal edges. They give great opportunities to architects and engineers for realization of their creative projects. Both the theoretical researches in the area of geometry of torses and strength analysis of shells and the influence of these researches on the application of torses in practice are shown. A presented research demonstrated that torses found the application in shipbuilding, aircraft construction, mechanical engineering, in architecture and building, engineering equipment and communications, in road building, in anti-erosive banks, topography, and cartography, clothing articles of light industry, in sculptural forms, and in modelling with developable surfaces. It was confirmed by the references on great number of published works on the subject, real examples from practice, and by handing in 14 illustrations of real objects.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46949200","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-20DOI: 10.22363/1815-5235-2022-18-2-150-160
S. Cheremnykh
Thin-walled cylindrical shells are used in elements of highly loaded products of mechanical engineering and energy. Along with their frequent use in production, experimental research in laboratories is also carried out constantly. This allows to simulate the behavior of the shell when exposed to external forces. But sometimes conducting an experiment becomes little possible due to the limitation of the power of the experimental apparatus when modeling the corresponding conditions of exposure to the shell in practice, therefore, improving theoretical methods for calculating the limiting states of shells when working in the elastoplastic region is relevant. The purpose of the study is to verify the conformity of the results of the experiment conducted on a thin-walled cylindrical shell made of steel 45 (GOST 1050-2013) when exposed to the sample by stretching, compression and torsion forces with theoretical calculations based on the equations of the theory of elastic-plastic processes by A.A. Ilyushin. The equations of the defining relations of the theory of elastic-plastic processes by A.A. Ilyushin for arbitrary trajectories of complex loading and deformation of materials in the deviatory deformation space Э1-Э3 are presented. All theoretical results are checked for compliance with the experiment, the reliability of the existing theory of stability is assessed. The solution is presented in the form of graphs of the dependence of the vector and scalar properties of the material on the length of the arc of the deformation trajectory and other parameters. Numerical values are selectively presented for different loading stages.
{"title":"Theoretical and experimental modeling of deformation of a cylindrical shell made of 45 steel under complex loading","authors":"S. Cheremnykh","doi":"10.22363/1815-5235-2022-18-2-150-160","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-2-150-160","url":null,"abstract":"Thin-walled cylindrical shells are used in elements of highly loaded products of mechanical engineering and energy. Along with their frequent use in production, experimental research in laboratories is also carried out constantly. This allows to simulate the behavior of the shell when exposed to external forces. But sometimes conducting an experiment becomes little possible due to the limitation of the power of the experimental apparatus when modeling the corresponding conditions of exposure to the shell in practice, therefore, improving theoretical methods for calculating the limiting states of shells when working in the elastoplastic region is relevant. The purpose of the study is to verify the conformity of the results of the experiment conducted on a thin-walled cylindrical shell made of steel 45 (GOST 1050-2013) when exposed to the sample by stretching, compression and torsion forces with theoretical calculations based on the equations of the theory of elastic-plastic processes by A.A. Ilyushin. The equations of the defining relations of the theory of elastic-plastic processes by A.A. Ilyushin for arbitrary trajectories of complex loading and deformation of materials in the deviatory deformation space Э1-Э3 are presented. All theoretical results are checked for compliance with the experiment, the reliability of the existing theory of stability is assessed. The solution is presented in the form of graphs of the dependence of the vector and scalar properties of the material on the length of the arc of the deformation trajectory and other parameters. Numerical values are selectively presented for different loading stages.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49333271","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-07-20DOI: 10.22363/1815-5235-2022-18-2-104-110
Natig S. Rzayev
The aims of the research are to obtain and to solve equations of forced oscillations of beams made of different modular materials and located on a viscous elastic base. It is assumed that the beam, which has different resistance to expansion and compression and which is continuous and heterogeneous by thickness and length, performs forced oscillations under the action of a force that varies according to the cross-harmonic law. When solving the problem, the resistance of the environment is taken into account. Since the equation of motion is a complicated differential equation with partial derivatives with respect to bending, it is solved by approximate analytical methods. At the first stage, decomposition into variables is used, and at the second stage, the Bubnov - Galerkin orthogonalization method is used. Equations of dependence between the circular frequency and parameters characterizing the resistance of the external environment and heterogeneity are obtained. Calculations were carried out for the specific values of characteristic functions. Results are represented in the form of tables and curves of the corresponding dependencies. It is clear from the obtained equations that serious errors are made in solving problems of oscillating motion without taking into account the resistance of the environment and different modularity. In addition to this, as the values of parameters that determine the heterogeneity of the density increase, the value of the frequency difference changes significantly. The results can be used in reports on solidity, stability and gain-frequency characteristic of different modular beams, boards and cylindrical coatings, taking into account the resistance of the environment.
{"title":"Forced oscillations of a multimodular beam on a viscous elastic base","authors":"Natig S. Rzayev","doi":"10.22363/1815-5235-2022-18-2-104-110","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-2-104-110","url":null,"abstract":"The aims of the research are to obtain and to solve equations of forced oscillations of beams made of different modular materials and located on a viscous elastic base. It is assumed that the beam, which has different resistance to expansion and compression and which is continuous and heterogeneous by thickness and length, performs forced oscillations under the action of a force that varies according to the cross-harmonic law. When solving the problem, the resistance of the environment is taken into account. Since the equation of motion is a complicated differential equation with partial derivatives with respect to bending, it is solved by approximate analytical methods. At the first stage, decomposition into variables is used, and at the second stage, the Bubnov - Galerkin orthogonalization method is used. Equations of dependence between the circular frequency and parameters characterizing the resistance of the external environment and heterogeneity are obtained. Calculations were carried out for the specific values of characteristic functions. Results are represented in the form of tables and curves of the corresponding dependencies. It is clear from the obtained equations that serious errors are made in solving problems of oscillating motion without taking into account the resistance of the environment and different modularity. In addition to this, as the values of parameters that determine the heterogeneity of the density increase, the value of the frequency difference changes significantly. The results can be used in reports on solidity, stability and gain-frequency characteristic of different modular beams, boards and cylindrical coatings, taking into account the resistance of the environment.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47077762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-23DOI: 10.22363/1815-5235-2022-18-1-64-72
L. Alborova, S. V. Strashnov
In 1972, I.I. Kotov proposed to separate the surfaces of congruent sections into a separate class and to include the surfaces of plane-and-parallel translation, surfaces of revolution, carved surfaces of Monge, cyclic surfaces with a generatrix circle of constant radius, rotative, spiroidal, and helical surfaces in it. The aim of the research is to obtain generalized parametric equations of surfaces of congruent sections of the pendulum type on right cylinders with plane-and-parallel translation of movable rigid superellipses. Analytical geometry methods are used. Computer systems MathCad and AutoCAD are applied to visualize surfaces. The results consist in the derivation of parametric equations of the studied surfaces in a general form convenient for the use of computer modeling methods. The technique is demonstrated on five examples with congruent mobile superellipses. The possibility of using obtained surface shapes in parametric architecture, free-form architecture, and in shaping of the surfaces of some technical products is noted.
{"title":"Surfaces of congruent sections of pendulum type on cylinders with generatrix superellipses","authors":"L. Alborova, S. V. Strashnov","doi":"10.22363/1815-5235-2022-18-1-64-72","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-1-64-72","url":null,"abstract":"In 1972, I.I. Kotov proposed to separate the surfaces of congruent sections into a separate class and to include the surfaces of plane-and-parallel translation, surfaces of revolution, carved surfaces of Monge, cyclic surfaces with a generatrix circle of constant radius, rotative, spiroidal, and helical surfaces in it. The aim of the research is to obtain generalized parametric equations of surfaces of congruent sections of the pendulum type on right cylinders with plane-and-parallel translation of movable rigid superellipses. Analytical geometry methods are used. Computer systems MathCad and AutoCAD are applied to visualize surfaces. The results consist in the derivation of parametric equations of the studied surfaces in a general form convenient for the use of computer modeling methods. The technique is demonstrated on five examples with congruent mobile superellipses. The possibility of using obtained surface shapes in parametric architecture, free-form architecture, and in shaping of the surfaces of some technical products is noted.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48539464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-23DOI: 10.22363/1815-5235-2022-18-1-22-34
E. Larionov, Marina I. Rynkovskaya, E. A. Grinko
Some approaches to the derivation of rheological equations of the mechanical state of concrete are considered and the principle of superposition of fraction deformations is justified in a nonlinear statement. In linear creep theory, this principle is known as L. Boltzmann’s superposition principle of fraction creep deformations. The concept of the strength structure of the constructive material is the basis for substantiating the statements given in this work. The statistical distribution of the strength of the fractions forming a structural element in the union allows the derivation of nonlinear equations of state. At the same time, the so-called structural stresses of fractions that capable to force resistance are considered. The overlay principle of fraction deformations in non-linear statement is justified. This means the modification of L. Boltzmann’s principle of superposition allowing its applicability also under the nonlinear dependence of deformations on stresses. It is established that the integral equation of state, which is nonlinear with respect to calculated stresses, is linear with respect to structural stresses. It is this circumstance that permits its reduction to a simple linear differential equation, which, in particular, simplifies the solution of relaxation problems. These problems are closely related to the calculation of structures for long-term safety.
{"title":"Rheological equations of concrete state and relaxation of stress","authors":"E. Larionov, Marina I. Rynkovskaya, E. A. Grinko","doi":"10.22363/1815-5235-2022-18-1-22-34","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-1-22-34","url":null,"abstract":"Some approaches to the derivation of rheological equations of the mechanical state of concrete are considered and the principle of superposition of fraction deformations is justified in a nonlinear statement. In linear creep theory, this principle is known as L. Boltzmann’s superposition principle of fraction creep deformations. The concept of the strength structure of the constructive material is the basis for substantiating the statements given in this work. The statistical distribution of the strength of the fractions forming a structural element in the union allows the derivation of nonlinear equations of state. At the same time, the so-called structural stresses of fractions that capable to force resistance are considered. The overlay principle of fraction deformations in non-linear statement is justified. This means the modification of L. Boltzmann’s principle of superposition allowing its applicability also under the nonlinear dependence of deformations on stresses. It is established that the integral equation of state, which is nonlinear with respect to calculated stresses, is linear with respect to structural stresses. It is this circumstance that permits its reduction to a simple linear differential equation, which, in particular, simplifies the solution of relaxation problems. These problems are closely related to the calculation of structures for long-term safety.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47954003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-23DOI: 10.22363/1815-5235-2022-18-1-35-44
Damir M. Khusainov, Aydar F. Salimov, A. G. Khabibulina
A new way to strengthen arched buildings with insufficient bearing capacity of the supports for the perception of the strut is proposed. That method can be implemented in the conditions of architectural and structural solutions of buildings with the presence of zones which prevent the traditional placement of puffs. There are no research results on this problem in the literature. On the example of a frameless arched building with insufficient bearing capacity of the supports for the perception of the strut, the application of the anticipated reinforcement method is considered with the reduction of two options for anchoring the supports of the arched building with puffs installed for the perception of the strut to semi-buried and sunken ground anchor. For the arched building under consideration, theoretical studies were carried out to determine the prestress value in the installed puffs, at which the load-bearing capacity of the arched building is provided for the variant of the asymmetric snow design load. The significance of the obtained results for the construction industry is that for the first time a method of strengthening arched buildings with insufficient bearing capacity of supports for the perception of the strut is suggested. The projected method of reinforcement is an effective, novel way to increase the load-bearing capacity of structures and supports of arched buildings and can be used in the conditions of architectural and structural solutions of buildings with the presence of zones that prevent the traditional placement of puffs.
{"title":"A method for strengthening arched buildings with insufficient bearing capacity of supports for the perception of the strut","authors":"Damir M. Khusainov, Aydar F. Salimov, A. G. Khabibulina","doi":"10.22363/1815-5235-2022-18-1-35-44","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-1-35-44","url":null,"abstract":"A new way to strengthen arched buildings with insufficient bearing capacity of the supports for the perception of the strut is proposed. That method can be implemented in the conditions of architectural and structural solutions of buildings with the presence of zones which prevent the traditional placement of puffs. There are no research results on this problem in the literature. On the example of a frameless arched building with insufficient bearing capacity of the supports for the perception of the strut, the application of the anticipated reinforcement method is considered with the reduction of two options for anchoring the supports of the arched building with puffs installed for the perception of the strut to semi-buried and sunken ground anchor. For the arched building under consideration, theoretical studies were carried out to determine the prestress value in the installed puffs, at which the load-bearing capacity of the arched building is provided for the variant of the asymmetric snow design load. The significance of the obtained results for the construction industry is that for the first time a method of strengthening arched buildings with insufficient bearing capacity of supports for the perception of the strut is suggested. The projected method of reinforcement is an effective, novel way to increase the load-bearing capacity of structures and supports of arched buildings and can be used in the conditions of architectural and structural solutions of buildings with the presence of zones that prevent the traditional placement of puffs.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42581985","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-23DOI: 10.22363/1815-5235-2022-18-1-54-63
V. Galishnikova, S. M. Elroba, N. Dayoub, Ahmad Sakna
Microbiologically induced calcite precipitation, or calcium carbonate CaCO3, is used in remediating cracks and fissures in concrete. Since the microbial activity is pollution-free, natural, that process is extremely desired and may solve concrete cracking without sacrificing mechanical properties. The effects of different nutrient on the self-healing process are elucidated. Nutrients provide the required sources of energy for the bacterial growth and metabolic activities. A species of bacteria Bacillus sphaericus was added to the cement mix at a ratio of 0.6% of cement weight with three organic compounds for nutrients (calcium lactate, yeast extract and peptone) at 0.30% of cement weight. Effects on setting time, rate of water absorption, compressive strength and flexural strength were studied. It was found that bacteria nutrition acts as an accelerator for cement pastes for initial setting time mortar, while acts as a retarder of cement pastes for final setting time for all bacterial compared to control mortar. Finally, bacterial mortars with different types of nutrients showed an increase in compressive and flexural strengths with yeast extract showing the most promising enhancements, resulting in 26.5 and 60% increase in compressive and flexural strength respectively.
{"title":"Use of natural compounds as a nutrition for bacteria in self-healing mortar","authors":"V. Galishnikova, S. M. Elroba, N. Dayoub, Ahmad Sakna","doi":"10.22363/1815-5235-2022-18-1-54-63","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-1-54-63","url":null,"abstract":"Microbiologically induced calcite precipitation, or calcium carbonate CaCO3, is used in remediating cracks and fissures in concrete. Since the microbial activity is pollution-free, natural, that process is extremely desired and may solve concrete cracking without sacrificing mechanical properties. The effects of different nutrient on the self-healing process are elucidated. Nutrients provide the required sources of energy for the bacterial growth and metabolic activities. A species of bacteria Bacillus sphaericus was added to the cement mix at a ratio of 0.6% of cement weight with three organic compounds for nutrients (calcium lactate, yeast extract and peptone) at 0.30% of cement weight. Effects on setting time, rate of water absorption, compressive strength and flexural strength were studied. It was found that bacteria nutrition acts as an accelerator for cement pastes for initial setting time mortar, while acts as a retarder of cement pastes for final setting time for all bacterial compared to control mortar. Finally, bacterial mortars with different types of nutrients showed an increase in compressive and flexural strengths with yeast extract showing the most promising enhancements, resulting in 26.5 and 60% increase in compressive and flexural strength respectively.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42017394","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-23DOI: 10.22363/1815-5235-2022-18-1-11-21
O. Osovskikh, Evgeny V. Osovskikh, V. Travush
The calculation for stability against progressive collapse in a dynamic setting, regulated by the norms, contains general recommendations on the possibility of taking into account a pliable foundation and including non-load-bearing elements in the calculation model without determining the limits of their applicability. The results of experimental studies and numerical analysis of a reinforced concrete experimental design of a spatial frame - a fragment of the frame of a multi-storey building in limiting and transcendental states are compared. The features of deformation of the structural system before and after the beyond-design impact, which causes its sudden structural restructuring, are established. Numerical studies were performed with and without considering the pliable foundation, as well as including or not including non-load-bearing elements in the calculation. Satisfactory agreement between the data of experimental studies and the results of dynamic calculation has been obtained. As one of the variants of the calculation model, a modified scheme was adopted, the constituent part of which are the elements of the calculation model of the second level - a fragment of the frame, modeled by volumetric and flat finite elements. It has been established that the results of the dynamic calculation of the experimental fragment are consistent with the experimental data only when taking into account the elements of the load device and real boundary conditions, including the deformable base.
{"title":"Determination of the survivability parameters of a reinforced concrete spatial frame operating under conditions of a complex stress state","authors":"O. Osovskikh, Evgeny V. Osovskikh, V. Travush","doi":"10.22363/1815-5235-2022-18-1-11-21","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-1-11-21","url":null,"abstract":"The calculation for stability against progressive collapse in a dynamic setting, regulated by the norms, contains general recommendations on the possibility of taking into account a pliable foundation and including non-load-bearing elements in the calculation model without determining the limits of their applicability. The results of experimental studies and numerical analysis of a reinforced concrete experimental design of a spatial frame - a fragment of the frame of a multi-storey building in limiting and transcendental states are compared. The features of deformation of the structural system before and after the beyond-design impact, which causes its sudden structural restructuring, are established. Numerical studies were performed with and without considering the pliable foundation, as well as including or not including non-load-bearing elements in the calculation. Satisfactory agreement between the data of experimental studies and the results of dynamic calculation has been obtained. As one of the variants of the calculation model, a modified scheme was adopted, the constituent part of which are the elements of the calculation model of the second level - a fragment of the frame, modeled by volumetric and flat finite elements. It has been established that the results of the dynamic calculation of the experimental fragment are consistent with the experimental data only when taking into account the elements of the load device and real boundary conditions, including the deformable base.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47432590","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2022-05-23DOI: 10.22363/1815-5235-2022-18-1-45-53
V. B. Zylev, P. O. Platnov
The work is devoted to improving the methods of experimental determination of internal friction parameters in materials. The aim of the laboratory experiments is to obtain physical parameters of the material that allow to take into account the damping forces in a uniaxial stress state. The research is focused on the internal friction model, which is based on the use of the generalized Prandtl model, that gives frequency-independent internal friction and allowing for the dependence of internal friction on the level of time-varying stresses. Damped oscillations during pure bending are recorded on a specially made laboratory installation. The description of the installation, the reference points of which coincide with the fixed points of the realized form of natural oscillations, is provided. The algorithm of cameral processing of experimental data is obtained. It is proposed to use a virtual system equivalent in damping. This is a system with one dynamic degree of freedom. The involvement of an imaginary system permits, after performing tests of the sample for pure bending, to acquire data corresponding to stretching - compression. The technique grants the use of long samples, which reduces the negative effect of stress concentration in the anchorages. The damping equivalent scheme makes it possible to use samples with an arbitrary cross-section. The found damping parameters for low-carbon steel are given.
{"title":"Models equivalent in damping in experiments for determining the parameters of internal friction in materials","authors":"V. B. Zylev, P. O. Platnov","doi":"10.22363/1815-5235-2022-18-1-45-53","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-1-45-53","url":null,"abstract":"The work is devoted to improving the methods of experimental determination of internal friction parameters in materials. The aim of the laboratory experiments is to obtain physical parameters of the material that allow to take into account the damping forces in a uniaxial stress state. The research is focused on the internal friction model, which is based on the use of the generalized Prandtl model, that gives frequency-independent internal friction and allowing for the dependence of internal friction on the level of time-varying stresses. Damped oscillations during pure bending are recorded on a specially made laboratory installation. The description of the installation, the reference points of which coincide with the fixed points of the realized form of natural oscillations, is provided. The algorithm of cameral processing of experimental data is obtained. It is proposed to use a virtual system equivalent in damping. This is a system with one dynamic degree of freedom. The involvement of an imaginary system permits, after performing tests of the sample for pure bending, to acquire data corresponding to stretching - compression. The technique grants the use of long samples, which reduces the negative effect of stress concentration in the anchorages. The damping equivalent scheme makes it possible to use samples with an arbitrary cross-section. The found damping parameters for low-carbon steel are given.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47329812","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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