Pub Date : 2023-09-30DOI: 10.22363/1815-5235-2023-19-3-302-312
Vladimir A. Rybakov
Lightweight steel-concrete structures (LSCS) are a type of steel-concrete structures where the filling concrete is monolithic (pouring) foam concrete with density 100-1000 kg/m3, the profile steel is lightweight steel thin-walled structures (LSTS), and fiber cement panels perform the function of non-removable formwork. As a rule, these structures are made of structural and heat-insulating foam concrete, which has good insulation and technical characteristics and sufficient strength. The object of the study is lightweight steel-concrete slab panels, which are one of the special cases of LSCS, made of monolithic foam concrete with density of 400 kg/m3. An analysis of the bending stiffness of LSBC slab panels by comparing the experimental data with analytical calculations was carried out. It was found that bendable LSCS made of monolithic foam concrete with density of 400 kg/m3 operate in physical nonlinear way. It was shown that the bending stiffness of LSCS floor panels can be determined as the sum of stiffnesses of profiled steel and foam concrete at the linear stage of work. The reliability of the proposed methodology within the limits of linear operation was demonstrated. It was proved both experimentally and theoretically that the bending stiffness of panels based on LSCS is higher than the bending stiffness of similar panels made of lightweight thin-walled steel (LTSS) by about 30%.
{"title":"Flexural stiffness of lightweight steel-concrete slab panels made of low-density foam concrete","authors":"Vladimir A. Rybakov","doi":"10.22363/1815-5235-2023-19-3-302-312","DOIUrl":"https://doi.org/10.22363/1815-5235-2023-19-3-302-312","url":null,"abstract":"Lightweight steel-concrete structures (LSCS) are a type of steel-concrete structures where the filling concrete is monolithic (pouring) foam concrete with density 100-1000 kg/m3, the profile steel is lightweight steel thin-walled structures (LSTS), and fiber cement panels perform the function of non-removable formwork. As a rule, these structures are made of structural and heat-insulating foam concrete, which has good insulation and technical characteristics and sufficient strength. The object of the study is lightweight steel-concrete slab panels, which are one of the special cases of LSCS, made of monolithic foam concrete with density of 400 kg/m3. An analysis of the bending stiffness of LSBC slab panels by comparing the experimental data with analytical calculations was carried out. It was found that bendable LSCS made of monolithic foam concrete with density of 400 kg/m3 operate in physical nonlinear way. It was shown that the bending stiffness of LSCS floor panels can be determined as the sum of stiffnesses of profiled steel and foam concrete at the linear stage of work. The reliability of the proposed methodology within the limits of linear operation was demonstrated. It was proved both experimentally and theoretically that the bending stiffness of panels based on LSCS is higher than the bending stiffness of similar panels made of lightweight thin-walled steel (LTSS) by about 30%.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135039367","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 : 2023-09-30DOI: 10.22363/1815-5235-2023-19-3-322-328
Galina E. Okolnikova, Svetlana B. Strashnova, Sikhanyisiwe Mercy Mabhena, Stanislav V. Strashnov
The adoption in construction of composite materials made by combining two or more materials to produce a material with improved properties over the separate components has been steadily increasing over the past decades. In the past few years there have been advances in composite manufacturing technology, increased demand for sustainable and eco-friendly building materials, and the need for materials that are lightweight and easy for transportation. For these reason, architects and civil engineers incorporate composites into structural elements to achieve these desired goals and optimize the cost of construction. One of the most common composite materials that was introduced to the industry is fiber reinforced polymer (FRP), produced by combining fibers (carbon, glass, or aramid) with a polymer matrix (epoxy or polyester). FRP materials are lightweight, durable and corrosion resistant, which makes them ideal for use in a wide range of construction applications. This study aims to propose a comparison between four different methods as a viable solution to strengthen and reinforce column structures. The structural behavior of three different composite materials was investigated. One traditional concrete-steel column was tested in the experiment for comparison. The other three columns were reinforced using carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP) and stainless steel respectively. The obtained experimental results were analyzed, and comparison of three different systems of reinforcement for strengthening columns with composite materials was performed.
{"title":"Reinforcement of columns using different composite materials","authors":"Galina E. Okolnikova, Svetlana B. Strashnova, Sikhanyisiwe Mercy Mabhena, Stanislav V. Strashnov","doi":"10.22363/1815-5235-2023-19-3-322-328","DOIUrl":"https://doi.org/10.22363/1815-5235-2023-19-3-322-328","url":null,"abstract":"The adoption in construction of composite materials made by combining two or more materials to produce a material with improved properties over the separate components has been steadily increasing over the past decades. In the past few years there have been advances in composite manufacturing technology, increased demand for sustainable and eco-friendly building materials, and the need for materials that are lightweight and easy for transportation. For these reason, architects and civil engineers incorporate composites into structural elements to achieve these desired goals and optimize the cost of construction. One of the most common composite materials that was introduced to the industry is fiber reinforced polymer (FRP), produced by combining fibers (carbon, glass, or aramid) with a polymer matrix (epoxy or polyester). FRP materials are lightweight, durable and corrosion resistant, which makes them ideal for use in a wide range of construction applications. This study aims to propose a comparison between four different methods as a viable solution to strengthen and reinforce column structures. The structural behavior of three different composite materials was investigated. One traditional concrete-steel column was tested in the experiment for comparison. The other three columns were reinforced using carbon fiber reinforced plastic (CFRP), glass fiber reinforced plastic (GFRP) and stainless steel respectively. The obtained experimental results were analyzed, and comparison of three different systems of reinforcement for strengthening columns with composite materials was performed.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135039362","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 : 2023-09-05DOI: 10.22363/1815-5235-2023-19-2-186-198
Alexander D. Beglov, Rudolf S. Sanzharovskiy, T. Ter-Emmanuilyan
The authors analyze the theory used in many countries, containing two independent directions: 1) the theory of stability of rod systems, including flat frames; 2) the theory of calculation of structural elements from various materials. The main feature of these theories is the application of the principle of plastic fracture. The assumption about a plastic hinge, due to the inconsistency with the experimental data, is supplemented by the incorrect application of theories of infinite elastic deformations, as well as of infinite creep deformations, which are incompatible with this hinge. Using the rules of mathematics, the principles of mechanics and the results of reliable experiments, it has been revealed that the analyzed theory contains several theories for different applications that reject each other, including the erroneous ones.
{"title":"Theory of short-term and long-term resistance of structures based on the principle of plastic fracture","authors":"Alexander D. Beglov, Rudolf S. Sanzharovskiy, T. Ter-Emmanuilyan","doi":"10.22363/1815-5235-2023-19-2-186-198","DOIUrl":"https://doi.org/10.22363/1815-5235-2023-19-2-186-198","url":null,"abstract":"The authors analyze the theory used in many countries, containing two independent directions: 1) the theory of stability of rod systems, including flat frames; 2) the theory of calculation of structural elements from various materials. The main feature of these theories is the application of the principle of plastic fracture. The assumption about a plastic hinge, due to the inconsistency with the experimental data, is supplemented by the incorrect application of theories of infinite elastic deformations, as well as of infinite creep deformations, which are incompatible with this hinge. Using the rules of mathematics, the principles of mechanics and the results of reliable experiments, it has been revealed that the analyzed theory contains several theories for different applications that reject each other, including the erroneous ones.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48095953","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 : 2023-09-05DOI: 10.22363/1815-5235-2023-19-2-149-161
V. B. Zylev, P. O. Platnov
The work is focused on creating a method for accounting of internal friction, which provides frequency independence, considers the dependence of internal friction on the level of the stress state, and is suitable for physically nonlinear tasks at large and small displacements. The authors consider an approximated method of accounting the damping in plates using the rod approximation according to A.R. Rzhanitsyn. An analysis of the discrete Rzhanitsyn medium with a square cell is given in terms of isotropy of its damping properties. The exact fulfillment of the isotropic damping properties is shown for the eight specific directions in the orientation of the deformations. The solution for a test example is given, where a rod oscillating in tension is calculated according to two computational schemes. One of these schemes is a real rod, the other is a rectangular plate experiencing uniaxial tension, and for its dynamic modeling, in turn, the discrete model by A.R. Rzhanitsyn is applied. The use of the same damping parameters for the real rod and rods in the Rzhanitsyn approximation leads to close damping. An approximate approach has been developed to account for internal friction during vibrations of a two-dimensional continuous medium, as well as a variant of clarifying the damping forces in the plate. A numerical example of damping modeling is given in the case of considering geometrically and physically nonlinear oscillations.
{"title":"Consideration of damping in a continuous medium using the rod approximation by A.R. Rzhanitsyn","authors":"V. B. Zylev, P. O. Platnov","doi":"10.22363/1815-5235-2023-19-2-149-161","DOIUrl":"https://doi.org/10.22363/1815-5235-2023-19-2-149-161","url":null,"abstract":"The work is focused on creating a method for accounting of internal friction, which provides frequency independence, considers the dependence of internal friction on the level of the stress state, and is suitable for physically nonlinear tasks at large and small displacements. The authors consider an approximated method of accounting the damping in plates using the rod approximation according to A.R. Rzhanitsyn. An analysis of the discrete Rzhanitsyn medium with a square cell is given in terms of isotropy of its damping properties. The exact fulfillment of the isotropic damping properties is shown for the eight specific directions in the orientation of the deformations. The solution for a test example is given, where a rod oscillating in tension is calculated according to two computational schemes. One of these schemes is a real rod, the other is a rectangular plate experiencing uniaxial tension, and for its dynamic modeling, in turn, the discrete model by A.R. Rzhanitsyn is applied. The use of the same damping parameters for the real rod and rods in the Rzhanitsyn approximation leads to close damping. An approximate approach has been developed to account for internal friction during vibrations of a two-dimensional continuous medium, as well as a variant of clarifying the damping forces in the plate. A numerical example of damping modeling is given in the case of considering geometrically and physically nonlinear oscillations.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44991935","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 : 2023-09-05DOI: 10.22363/1815-5235-2023-19-2-162-177
V. Agapov, A. S. Markovich, K. Aidemirov
Modern construction standards and regulations prescribe to carry out calculations of concrete and reinforced concrete structures in a nonlinear formulation with account of the real properties of concrete and reinforcement. However, the most of finite-element program complexes cannot perform such calculations in a nonlinear formulation with account of plastic deformations of concrete and reinforcement. To solve this problem, a methodology has been developed and a solid finite element adapted to the PRINS computing complex has been created, which made it possible to perform calculations of reinforced concrete structures considering their actual work. The aim of the study - development and implementation of a method for calculating reinforced concrete structures under conditions of a three-dimensional stress state, considering both brittle fracture and elastic-plastic deformation of concrete. A finite-element methodology, algorithm, and program for calculation of massive reinforced concrete structures with account of plastic deformations of concrete have been presented. The methodology is based on the modified Willam and Warnke strength criterion supplemented with the flow criterion. Two models of volumetric deformation of concrete have been regarded: the elastic model at brittle failure and the ideal elastoplastic model. An eight-node finite element with linear approximating functions of displacements implementing the mentioned deformation models is created. Verification calculations of a massive concrete structure in three-axial compression testify to the accuracy and convergence of the developed finite elements. The PRINS can be effectively used by engineers of designing and scientific organizations to solve a wide class of engineering problems related to calculations of building structures.
{"title":"Models of nonlinear deformation of concrete in a triaxial stress state and their implementation in the PRINS computational complex","authors":"V. Agapov, A. S. Markovich, K. Aidemirov","doi":"10.22363/1815-5235-2023-19-2-162-177","DOIUrl":"https://doi.org/10.22363/1815-5235-2023-19-2-162-177","url":null,"abstract":"Modern construction standards and regulations prescribe to carry out calculations of concrete and reinforced concrete structures in a nonlinear formulation with account of the real properties of concrete and reinforcement. However, the most of finite-element program complexes cannot perform such calculations in a nonlinear formulation with account of plastic deformations of concrete and reinforcement. To solve this problem, a methodology has been developed and a solid finite element adapted to the PRINS computing complex has been created, which made it possible to perform calculations of reinforced concrete structures considering their actual work. The aim of the study - development and implementation of a method for calculating reinforced concrete structures under conditions of a three-dimensional stress state, considering both brittle fracture and elastic-plastic deformation of concrete. A finite-element methodology, algorithm, and program for calculation of massive reinforced concrete structures with account of plastic deformations of concrete have been presented. The methodology is based on the modified Willam and Warnke strength criterion supplemented with the flow criterion. Two models of volumetric deformation of concrete have been regarded: the elastic model at brittle failure and the ideal elastoplastic model. An eight-node finite element with linear approximating functions of displacements implementing the mentioned deformation models is created. Verification calculations of a massive concrete structure in three-axial compression testify to the accuracy and convergence of the developed finite elements. The PRINS can be effectively used by engineers of designing and scientific organizations to solve a wide class of engineering problems related to calculations of building structures.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42035573","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 : 2023-09-05DOI: 10.22363/1815-5235-2023-19-2-178-185
V. Rimshin, P. Truntov
One of the main causes for deterioration of reinforced concrete structures in modern construction is corrosion of reinforcement. Corrosion leads to decrease of adhesion between reinforcement and concrete, formation of cracks and destruction of the protective layer of concrete. All this reduces the load-bearing capacity of reinforced concrete structures. The structures of sludge reservoirs exposed to carbon dioxide were used as an object of the study. The characteristic defects and damages revealed by visual inspection were described. The verification calculation of the considered construction depending on the pH of the medium was performed on the basis of the results of technical inspection and study. The degree of carbon dioxide impact on the considered structures was determined by the phenolphthalein test method, which is based on the color change of acid-base indicator solution on the surface of concrete and reinforced concrete depending on the pH value of its medium. The phenolphthalein test revealed that pH of the medium is less than 8 for the depth more than the thickness of the concrete protective layer. A verification calculation of the considered structure was performed on the basis of the technical inspection results and the conducted research. According to the calculation results, a variant of beam reconstruction and strengthening using external reinforcement based on carbon fibers FibARM 230/150 was proposed. The reconstruction was carried out with account of the carbonized concrete layer.
{"title":"Strengthening of reinforced concrete structures by composite materials taking into consideration the carbonization of concrete","authors":"V. Rimshin, P. Truntov","doi":"10.22363/1815-5235-2023-19-2-178-185","DOIUrl":"https://doi.org/10.22363/1815-5235-2023-19-2-178-185","url":null,"abstract":"One of the main causes for deterioration of reinforced concrete structures in modern construction is corrosion of reinforcement. Corrosion leads to decrease of adhesion between reinforcement and concrete, formation of cracks and destruction of the protective layer of concrete. All this reduces the load-bearing capacity of reinforced concrete structures. The structures of sludge reservoirs exposed to carbon dioxide were used as an object of the study. The characteristic defects and damages revealed by visual inspection were described. The verification calculation of the considered construction depending on the pH of the medium was performed on the basis of the results of technical inspection and study. The degree of carbon dioxide impact on the considered structures was determined by the phenolphthalein test method, which is based on the color change of acid-base indicator solution on the surface of concrete and reinforced concrete depending on the pH value of its medium. The phenolphthalein test revealed that pH of the medium is less than 8 for the depth more than the thickness of the concrete protective layer. A verification calculation of the considered structure was performed on the basis of the technical inspection results and the conducted research. According to the calculation results, a variant of beam reconstruction and strengthening using external reinforcement based on carbon fibers FibARM 230/150 was proposed. The reconstruction was carried out with account of the carbonized concrete layer.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43553672","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 : 2023-09-05DOI: 10.22363/1815-5235-2023-19-2-233-250
M. Hematibahar, Alireza Esparham, N. Vatin, M. Kharun, T. Gebre
The objective of the research is to study the effect of different additives on the conventional concrete. In this term, three types of materials have been added to the concrete: gelatin powder as the binder, recycled aggregates, and almond shell as the fine and coarse aggregates. Several experiments have been made tо determine physical and mechanical properties, such as test for compressive and tensile strengths, for impact loading strength, durability test (water absorption) and deep penetration tests. Moreover, the microstructure results for the new type of concrete have been studied by means of scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDXS). The results show that when 70 kg of gelatin powder is added to 1 m3 of concrete, the concrete’s compressive strength and tensile strength are improved more than 22%; during impact loading the first and ultimate cracks are 11 and 129 by numbers, and the first and ultimate cracks’ strength is more than 223 and 2346 J respectively. The durability of sample from concrete with additional gelatin has been improved. SEM results illustrate that the weakness of almond shell concrete is related to cracks and voids between the cement matrix and almond shell. The voids of gelatin concrete are higher than that of conventional concrete. The conventional concrete has smooth crystals, and gelatin concrete has sharp and cubic crystals. EDXS results show that chemical content of these two types of concrete is different: conventional concrete contains silicon, while EDXS results show that chemical content of these two types of concrete is different: conventional concrete contains silicon, while gelatin concrete contains calcium and also C-S-H gel is generated in it.
{"title":"Effect of gelatin powder, almond shell, and recycled aggregates on chemical and mechanical properties of conventional concrete","authors":"M. Hematibahar, Alireza Esparham, N. Vatin, M. Kharun, T. Gebre","doi":"10.22363/1815-5235-2023-19-2-233-250","DOIUrl":"https://doi.org/10.22363/1815-5235-2023-19-2-233-250","url":null,"abstract":"The objective of the research is to study the effect of different additives on the conventional concrete. In this term, three types of materials have been added to the concrete: gelatin powder as the binder, recycled aggregates, and almond shell as the fine and coarse aggregates. Several experiments have been made tо determine physical and mechanical properties, such as test for compressive and tensile strengths, for impact loading strength, durability test (water absorption) and deep penetration tests. Moreover, the microstructure results for the new type of concrete have been studied by means of scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDXS). The results show that when 70 kg of gelatin powder is added to 1 m3 of concrete, the concrete’s compressive strength and tensile strength are improved more than 22%; during impact loading the first and ultimate cracks are 11 and 129 by numbers, and the first and ultimate cracks’ strength is more than 223 and 2346 J respectively. The durability of sample from concrete with additional gelatin has been improved. SEM results illustrate that the weakness of almond shell concrete is related to cracks and voids between the cement matrix and almond shell. The voids of gelatin concrete are higher than that of conventional concrete. The conventional concrete has smooth crystals, and gelatin concrete has sharp and cubic crystals. EDXS results show that chemical content of these two types of concrete is different: conventional concrete contains silicon, while EDXS results show that chemical content of these two types of concrete is different: conventional concrete contains silicon, while gelatin concrete contains calcium and also C-S-H gel is generated in it.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41423136","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 : 2023-09-05DOI: 10.22363/1815-5235-2023-19-2-199-209
Vladimir A. Repin, Anastasia V. Lukina, Alexey S. Usov
Wooden rafter structures have undoubted advantages, which determine their wide application. The object of the study is triangular rafter structures. The purpose of the research is to find the dependence of force values in the elements of the studied structure on the magnitude of its lifting boom. The calculation of a triangular truss using the Maxwell - Cremona diagram is presented. The efficiency of the proposed method was estimated on the basis of a study of the structure of a wooden truss of the “scissors” type. The following pattern has been established: the change in the coordinates of the points (abscissas) of the force diagram is inversely proportional to the change in f . It is determined the area of rational values of the lift (roof slope) at which the values of internal forces tend to a minimum. It was revealed that the values of force increments in the truss elements at each step increase from 27% to 2 times when the roof slope de-creases. Based on the graphical analysis of the obtained data the range of effective values of the roof slope at which the forces in the elements of the truss take minimum values was found. Using a graphic method of determining the forces, it is possible to check variants of the roof slope in the search for a rational solution of the “scissor” type truss structure. It follows that the proposed method contributes to the choice of the most economical structural solutions.
{"title":"Rational structural solutions for triangular trusses","authors":"Vladimir A. Repin, Anastasia V. Lukina, Alexey S. Usov","doi":"10.22363/1815-5235-2023-19-2-199-209","DOIUrl":"https://doi.org/10.22363/1815-5235-2023-19-2-199-209","url":null,"abstract":"Wooden rafter structures have undoubted advantages, which determine their wide application. The object of the study is triangular rafter structures. The purpose of the research is to find the dependence of force values in the elements of the studied structure on the magnitude of its lifting boom. The calculation of a triangular truss using the Maxwell - Cremona diagram is presented. The efficiency of the proposed method was estimated on the basis of a study of the structure of a wooden truss of the “scissors” type. The following pattern has been established: the change in the coordinates of the points (abscissas) of the force diagram is inversely proportional to the change in f . It is determined the area of rational values of the lift (roof slope) at which the values of internal forces tend to a minimum. It was revealed that the values of force increments in the truss elements at each step increase from 27% to 2 times when the roof slope de-creases. Based on the graphical analysis of the obtained data the range of effective values of the roof slope at which the forces in the elements of the truss take minimum values was found. Using a graphic method of determining the forces, it is possible to check variants of the roof slope in the search for a rational solution of the “scissor” type truss structure. It follows that the proposed method contributes to the choice of the most economical structural solutions.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49021260","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 : 2023-09-05DOI: 10.22363/1815-5235-2023-19-2-130-148
M. Sagdatullin
When modeling a nonlinear isotropic eight-node finite element, the main kinematic and physical relationships are determined. In particular, isoparametric approximations of the geometry and an unknown displacement increment vector, covariant and contravariant components of basis vectors, metric tensors, strain tensors (Cauchy - Green and Almansi) and true Cauchy stresses in the initial and current configuration are introduced. Next, a variational equation is introduced in the stress rates in the actual configuration without taking into account body forces and the Seth material is considered, where the Almansi strain tensor is used as the finite strain tensor. Linearization of this variational equation, discretization of the obtained relations (stiffness matrix, matrix of geometric stiffness) is carried out. The resulting expressions are written as a system of linear algebraic equations. Several test cases are considered. The problem of bending a strip into a ring is presented. This problem is solved analytically, based on kinematic and physical relationships. Examples of nonlinear deformation of cylindrical and spherical shells are also shown. The method proposed in this paper for constructing a three-dimensional finite element of the nonlinear theory of elasticity, using the Seth material, makes it possible to obtain a special finite element, with which it is quite realistic to calculate the stress state of shells of medium thickness using a single-layer approximation in thickness. The obtained results of test cases demonstrate the operability of the proposed technique.
{"title":"Numerical modeling of nonlinear deformation processes for shells of medium thickness","authors":"M. Sagdatullin","doi":"10.22363/1815-5235-2023-19-2-130-148","DOIUrl":"https://doi.org/10.22363/1815-5235-2023-19-2-130-148","url":null,"abstract":"When modeling a nonlinear isotropic eight-node finite element, the main kinematic and physical relationships are determined. In particular, isoparametric approximations of the geometry and an unknown displacement increment vector, covariant and contravariant components of basis vectors, metric tensors, strain tensors (Cauchy - Green and Almansi) and true Cauchy stresses in the initial and current configuration are introduced. Next, a variational equation is introduced in the stress rates in the actual configuration without taking into account body forces and the Seth material is considered, where the Almansi strain tensor is used as the finite strain tensor. Linearization of this variational equation, discretization of the obtained relations (stiffness matrix, matrix of geometric stiffness) is carried out. The resulting expressions are written as a system of linear algebraic equations. Several test cases are considered. The problem of bending a strip into a ring is presented. This problem is solved analytically, based on kinematic and physical relationships. Examples of nonlinear deformation of cylindrical and spherical shells are also shown. The method proposed in this paper for constructing a three-dimensional finite element of the nonlinear theory of elasticity, using the Seth material, makes it possible to obtain a special finite element, with which it is quite realistic to calculate the stress state of shells of medium thickness using a single-layer approximation in thickness. The obtained results of test cases demonstrate the operability of the proposed technique.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46327660","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 : 2023-09-05DOI: 10.22363/1815-5235-2023-19-2-210-219
S. Krivoshapko
Superellipses are becoming more and more in demand in various branches of science and national economy due to their versatility. They found the most application in shipbuilding. Suggestions for the use of superellips in architecture and construction have appeared recently. The author proposes explicit and parametric equations of surfaces with a main framework of three predetermined superellips lying in three coordinate planes. These equations describe a large set of analytical shapes suitable for the formation middle surfaces of thin building shells. One of the superellipses is taken in a form of a circle. The shells can be designed on circular and rhombic plans, and also on plans in the shape of superellips of general type with convex and concave sides. All recommended surfaces are illustrated in 24 examples using computer graphics. A network of curvilinear non-orthogonal coordinates is generated on the surfaces using dimensionless independent parameters. The considered surfaces can become a part of the reserve of surfaces for further application in real structures and facilities.
{"title":"Surfaces with a main framework of three given curves which include one circle","authors":"S. Krivoshapko","doi":"10.22363/1815-5235-2023-19-2-210-219","DOIUrl":"https://doi.org/10.22363/1815-5235-2023-19-2-210-219","url":null,"abstract":"Superellipses are becoming more and more in demand in various branches of science and national economy due to their versatility. They found the most application in shipbuilding. Suggestions for the use of superellips in architecture and construction have appeared recently. The author proposes explicit and parametric equations of surfaces with a main framework of three predetermined superellips lying in three coordinate planes. These equations describe a large set of analytical shapes suitable for the formation middle surfaces of thin building shells. One of the superellipses is taken in a form of a circle. The shells can be designed on circular and rhombic plans, and also on plans in the shape of superellips of general type with convex and concave sides. All recommended surfaces are illustrated in 24 examples using computer graphics. A network of curvilinear non-orthogonal coordinates is generated on the surfaces using dimensionless independent parameters. The considered surfaces can become a part of the reserve of surfaces for further application in real structures and facilities.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42705788","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：