Pub Date : 2022-12-15DOI: 10.22363/1815-5235-2022-18-6-534-543
E. Larionov, Vitaly G. Nazarenko, Marina I. Rynkovskaya, E. A. Grinko
The calculation and prediction of the long-term safety of building structures is associated with the dynamics of the stress state of their composite elements and leads to relaxation problems for assessing the redistribution of stresses between the components that make up the structural element. In this study, reinforced concrete elements and the redistribution of stress from concrete to reinforcement are considered. To solve the corresponding relaxation problem an approach based on the concept of the strength structure of materials is proposed, which considers them as a union of their fractions (layers, fibers) with statistically distributed strengths. The loss of the ability of force resistance caused by loading by part of the fractions of the element entails a redistribution of stresses to its entire fractions. As a result of this, a nonlinear dependence of deformations on the design stresses arises, calculated under the assumption of equal strength of all fractions. For a material isotropic in strength, the relaxation problem is reduced to solving a linear integral equation conjugated with its linear rheological equation. The linear integral equation relatively structural stresses is reduced. After solving it, the desired stress is determined as the root of the algebraic equation connecting the structural and design stresses. The proposed approach significantly simplifies the obtaining of necessary for the long-term safety prediction of structures stress estimates in the components of structural elements.
{"title":"Relaxation of stress in elements of reinforced concrete structures","authors":"E. Larionov, Vitaly G. Nazarenko, Marina I. Rynkovskaya, E. A. Grinko","doi":"10.22363/1815-5235-2022-18-6-534-543","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-6-534-543","url":null,"abstract":"The calculation and prediction of the long-term safety of building structures is associated with the dynamics of the stress state of their composite elements and leads to relaxation problems for assessing the redistribution of stresses between the components that make up the structural element. In this study, reinforced concrete elements and the redistribution of stress from concrete to reinforcement are considered. To solve the corresponding relaxation problem an approach based on the concept of the strength structure of materials is proposed, which considers them as a union of their fractions (layers, fibers) with statistically distributed strengths. The loss of the ability of force resistance caused by loading by part of the fractions of the element entails a redistribution of stresses to its entire fractions. As a result of this, a nonlinear dependence of deformations on the design stresses arises, calculated under the assumption of equal strength of all fractions. For a material isotropic in strength, the relaxation problem is reduced to solving a linear integral equation conjugated with its linear rheological equation. The linear integral equation relatively structural stresses is reduced. After solving it, the desired stress is determined as the root of the algebraic equation connecting the structural and design stresses. The proposed approach significantly simplifies the obtaining of necessary for the long-term safety prediction of structures stress estimates in the components of structural elements.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42835885","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 : 2022-12-15DOI: 10.22363/1815-5235-2022-18-6-544-551
Y. Leontiev, V. Travush
The authors deal with the vibration of the pipeline that occurs during the transportation of a gas-containing liquid due to the uneven distribution of gas accumulation along the length of the pipeline, which produces pulsating movements of the center of gravity of the moving liquid, when the conditions for supporting the middle part change. The solution is constructed using the calculation scheme of a beam lying on an elastic foundation described by the Winkler model. To assess the impact on the stress-strain state of the beam of the sudden exclusion of the elastic foundation under the middle part of the beam, the circular frequencies and forms of natural transverse vibrations of the beam that occur in the absence of disturbing forces are determined. The given solution of the problem of vibrations of a pipe, through which a gas-containing liquid is transported, with a change in the conditions of support of the middle part of the beam, can be used to predict the durability of the pipe.
{"title":"Fluctuations of pipelines of gas-containing liquids under changing bearing conditions","authors":"Y. Leontiev, V. Travush","doi":"10.22363/1815-5235-2022-18-6-544-551","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-6-544-551","url":null,"abstract":"The authors deal with the vibration of the pipeline that occurs during the transportation of a gas-containing liquid due to the uneven distribution of gas accumulation along the length of the pipeline, which produces pulsating movements of the center of gravity of the moving liquid, when the conditions for supporting the middle part change. The solution is constructed using the calculation scheme of a beam lying on an elastic foundation described by the Winkler model. To assess the impact on the stress-strain state of the beam of the sudden exclusion of the elastic foundation under the middle part of the beam, the circular frequencies and forms of natural transverse vibrations of the beam that occur in the absence of disturbing forces are determined. The given solution of the problem of vibrations of a pipe, through which a gas-containing liquid is transported, with a change in the conditions of support of the middle part of the beam, can be used to predict the durability of the pipe.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43552182","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 : 2022-12-15DOI: 10.22363/1815-5235-2022-18-6-525-533
V. Kolchunov
A variant of the numerical-analytical method in the nonlinear mechanics of reinforced concrete is proposed. Calculation models make it possible to take into account a number of important factors, such as discrete cracks, the effect of concrete discontinuity, and reinforcement reactions in a crack. When solving the inverse problem of determining the width of the crack opening, the deformation effect is not set, but is modeled using the “joining” of the assigned minimum possible width, its opening under the appropriate loading. In the calculation scheme, pairs of finite elements are distinguished, adjacent to such a crack from opposite special sides, called a two-element cantilever model. Pairs are considered in two states: before their jointing of cracks and after their jointing, taking into account the deformation effect and the effect of concrete discontinuity. The calculation algorithm is based on combinations of an analytical model for calculating the stiffness of complexly stressed structures and the intelligence of the “LIRA-SAPR” software package.
{"title":"Numerical-analytical method in reinforced concrete mechanics","authors":"V. Kolchunov","doi":"10.22363/1815-5235-2022-18-6-525-533","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-6-525-533","url":null,"abstract":"A variant of the numerical-analytical method in the nonlinear mechanics of reinforced concrete is proposed. Calculation models make it possible to take into account a number of important factors, such as discrete cracks, the effect of concrete discontinuity, and reinforcement reactions in a crack. When solving the inverse problem of determining the width of the crack opening, the deformation effect is not set, but is modeled using the “joining” of the assigned minimum possible width, its opening under the appropriate loading. In the calculation scheme, pairs of finite elements are distinguished, adjacent to such a crack from opposite special sides, called a two-element cantilever model. Pairs are considered in two states: before their jointing of cracks and after their jointing, taking into account the deformation effect and the effect of concrete discontinuity. The calculation algorithm is based on combinations of an analytical model for calculating the stiffness of complexly stressed structures and the intelligence of the “LIRA-SAPR” software package.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48026751","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 : 2022-12-15DOI: 10.22363/1815-5235-2022-18-6-503-514
N. Karpenko, Gennady A. Moiseenko
The authors review the results of complex theoretical studies of the physico-mechanical and rheological properties of high-strength steel-fiber concrete in comparison with non-reinforced fine-grained high-strength concrete made of self-compacting mixtures under short-term and long-term load exposure. Based on the data of extensive experimental studies, methods of Mathematical description of concrete properties depending on the key factors of influence have been selected and developed. A steel fiber concrete with a minimum content of the selected type of fiber is studied, at which the positive effect of fiber reinforcement begins to manifest itself. The theoretical approach of V.M. Bondarenko to the description of creep measures of steel fiber concrete has been developed. The developed methods can be used to calculate structures made of high-strength steel-fiber concrete using the modern diagram method.
{"title":"Investigation of the properties of high-strength steel fiber concrete with a minimum effective fiber content under loads of various durations","authors":"N. Karpenko, Gennady A. Moiseenko","doi":"10.22363/1815-5235-2022-18-6-503-514","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-6-503-514","url":null,"abstract":"The authors review the results of complex theoretical studies of the physico-mechanical and rheological properties of high-strength steel-fiber concrete in comparison with non-reinforced fine-grained high-strength concrete made of self-compacting mixtures under short-term and long-term load exposure. Based on the data of extensive experimental studies, methods of Mathematical description of concrete properties depending on the key factors of influence have been selected and developed. A steel fiber concrete with a minimum content of the selected type of fiber is studied, at which the positive effect of fiber reinforcement begins to manifest itself. The theoretical approach of V.M. Bondarenko to the description of creep measures of steel fiber concrete has been developed. The developed methods can be used to calculate structures made of high-strength steel-fiber concrete using the modern diagram method.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45341739","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 : 2022-12-15DOI: 10.22363/1815-5235-2022-18-6-564-572
S. Savin, N. Fedorova
Environmental impacts on reinforced concrete structures may cause a decrease of in resource of their robustness under design and unforeseen actions. The research in this field mainly focusses on investigation of the behavior of bending elements as eccentrically compressed and damaged by corrosion reinforced concrete elements such as columns require more intensive investigation. Thus, the study has the purpose to assess the influence of the depth of corrosion on the bearing capacity of eccentrically compressed reinforced concrete columns of building frames, as well as to evaluate the time for exhaustion of load capacity. The phenomenological model, which was proposed by V.M. Bon- darenko, has been adopted in order to account long-term processes of corrosion damage. The study established an increase in the depth of corrosion damage leads to a decrease in the bearing capacity of eccentrically compressed reinforced concrete columns since the effective cross-sectional depth decreases which makes column more flexible. The relative cross-sectional depth lost strength resistance resource due to corrosion varies depending on the current stress-strain state of the reinforced concrete column that is adaptation mechanism of the structure to long-term actions. The exposure of building structural systems under environmental damage depends significantly on the parameters of the action as well as the stress-strain state of the structural element. The paper established that it may differ by several times depending on avalanche or clogging damage scenario.
{"title":"Stability exposure of building structural systems under environmental damage","authors":"S. Savin, N. Fedorova","doi":"10.22363/1815-5235-2022-18-6-564-572","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-6-564-572","url":null,"abstract":"Environmental impacts on reinforced concrete structures may cause a decrease of in resource of their robustness under design and unforeseen actions. The research in this field mainly focusses on investigation of the behavior of bending elements as eccentrically compressed and damaged by corrosion reinforced concrete elements such as columns require more intensive investigation. Thus, the study has the purpose to assess the influence of the depth of corrosion on the bearing capacity of eccentrically compressed reinforced concrete columns of building frames, as well as to evaluate the time for exhaustion of load capacity. The phenomenological model, which was proposed by V.M. Bon- darenko, has been adopted in order to account long-term processes of corrosion damage. The study established an increase in the depth of corrosion damage leads to a decrease in the bearing capacity of eccentrically compressed reinforced concrete columns since the effective cross-sectional depth decreases which makes column more flexible. The relative cross-sectional depth lost strength resistance resource due to corrosion varies depending on the current stress-strain state of the reinforced concrete column that is adaptation mechanism of the structure to long-term actions. The exposure of building structural systems under environmental damage depends significantly on the parameters of the action as well as the stress-strain state of the structural element. The paper established that it may differ by several times depending on avalanche or clogging damage scenario.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45640784","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 : 2022-12-15DOI: 10.22363/1815-5235-2022-18-5-428-437
S. Lisichkin, S. S. Kotitsyna
The authors present the results of the analysis of field observations of the condition of the base slab of the water intake structure of hydroelectric power plant (including the stresses in the reinforcement in the areas of intersection with the vertical joints and the width of the opening of these joints). The aim of the study is to control the condition of the reinforced concrete structure of the foundation slab of the water inlet of the hydroelectric power plant, as well as to develop measures to strengthen the bottom section of the foundation slab in the areas of vertical interblock joints. In order to control the stress and strain of the base plate of the water intake of hydroelectric power plant, string control and measuring equipment was installed: on reinforcement rods - reinforcement dynamometers PSAS, on vertical interblock joints - displacement sensors PLPS. The field observations of the stress state of the reinforcement of the base slab of the water intake structure of hydroelectric power station showed that high values of tensile stresses, exceeding the design resistance of A500C class reinforcement (435 MPa), occurred in the reinforcement rods (directed along the flow), crossing the lower vertical interblock joints. There was also fixed the width of opening of the vertical interblock joint, reaching 1.28 mm. There was a necessity to strengthen the lower section of the foundation slab of the water intake structure of hydroelectric pumped storage power plant. For this purpose, inclined reinforcing bars (anchors) crossing the lower vertical interblock joints were installed. The outlet sections of the buttresses of the slab of the downstream section of the inlet to the downstream parapet were increased.
{"title":"Peculiarities of the condition of the foundation slab of the pumped storage power plant water intake","authors":"S. Lisichkin, S. S. Kotitsyna","doi":"10.22363/1815-5235-2022-18-5-428-437","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-5-428-437","url":null,"abstract":"The authors present the results of the analysis of field observations of the condition of the base slab of the water intake structure of hydroelectric power plant (including the stresses in the reinforcement in the areas of intersection with the vertical joints and the width of the opening of these joints). The aim of the study is to control the condition of the reinforced concrete structure of the foundation slab of the water inlet of the hydroelectric power plant, as well as to develop measures to strengthen the bottom section of the foundation slab in the areas of vertical interblock joints. In order to control the stress and strain of the base plate of the water intake of hydroelectric power plant, string control and measuring equipment was installed: on reinforcement rods - reinforcement dynamometers PSAS, on vertical interblock joints - displacement sensors PLPS. The field observations of the stress state of the reinforcement of the base slab of the water intake structure of hydroelectric power station showed that high values of tensile stresses, exceeding the design resistance of A500C class reinforcement (435 MPa), occurred in the reinforcement rods (directed along the flow), crossing the lower vertical interblock joints. There was also fixed the width of opening of the vertical interblock joint, reaching 1.28 mm. There was a necessity to strengthen the lower section of the foundation slab of the water intake structure of hydroelectric pumped storage power plant. For this purpose, inclined reinforcing bars (anchors) crossing the lower vertical interblock joints were installed. The outlet sections of the buttresses of the slab of the downstream section of the inlet to the downstream parapet were increased.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45103207","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 : 2022-12-15DOI: 10.22363/1815-5235-2022-18-6-515-524
A. Kolesnikov, Antonina V. Osadchaya
The authors deal with the structures of buildings in the form of shallow shells with some damage. The derivation of equations is given taking into account the geometric nonlinearity of the work of a thin-walled structure. A technique for solving systems of equations using the Bubnov - Galyorkin method is given. The work of the structure with various ways of fixing the edges is simulated. Damage is specified by changing the modulus of elasticity in an arbitrary section of the structure. The influence of the shape and location of the defect on the value of the critical load is investigated. The results of the studies carried out are given in a dimensionless form and illustrated by graphs, which makes it convenient to use them in engineering calculations. Recommendations are given for correcting the shape and thickness of coating structures in the form of shallow shells in order to maintain their bearing capacity in the event of defects. The proposed method can be used to determine and investigate the stress-strain state of structures in the form of shallow shells, taking into account the geometric nonlinearity of work in the presence of defects in them. The constructed graphs of the dependence of the critical load on various parameters make it possible to evaluate the operation of structures, taking into account changes in various factors at various stages of the structure's operation. The use of varying characteristics of the reduction in the modulus of elasticity, which appears because of the occurrence of a defect, shows results that are close to real conditions.
{"title":"Stability of shallow shells with local changes in strength characteristics","authors":"A. Kolesnikov, Antonina V. Osadchaya","doi":"10.22363/1815-5235-2022-18-6-515-524","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-6-515-524","url":null,"abstract":"The authors deal with the structures of buildings in the form of shallow shells with some damage. The derivation of equations is given taking into account the geometric nonlinearity of the work of a thin-walled structure. A technique for solving systems of equations using the Bubnov - Galyorkin method is given. The work of the structure with various ways of fixing the edges is simulated. Damage is specified by changing the modulus of elasticity in an arbitrary section of the structure. The influence of the shape and location of the defect on the value of the critical load is investigated. The results of the studies carried out are given in a dimensionless form and illustrated by graphs, which makes it convenient to use them in engineering calculations. Recommendations are given for correcting the shape and thickness of coating structures in the form of shallow shells in order to maintain their bearing capacity in the event of defects. The proposed method can be used to determine and investigate the stress-strain state of structures in the form of shallow shells, taking into account the geometric nonlinearity of work in the presence of defects in them. The constructed graphs of the dependence of the critical load on various parameters make it possible to evaluate the operation of structures, taking into account changes in various factors at various stages of the structure's operation. The use of varying characteristics of the reduction in the modulus of elasticity, which appears because of the occurrence of a defect, shows results that are close to real conditions.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41444533","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 : 2022-12-15DOI: 10.22363/1815-5235-2022-18-5-458-466
Mathieu Gil-oulbé, T. Daou, Ousmane Mariko
Geometers have proposed more than 600 analytical surfaces for implementation. The largest number of these surfaces is used in architecture and mechanical engineering. Although digital architecture and free form architecture are now increasingly influencing the design of long-span shell structures and curved buildings, the research and application of analytical surfaces continues on an increasing scale. The purpose of the research is to study the state of affairs in the application of analytical surfaces in the construction and engineering industries and to clarify the classes of surfaces that have found application in the study of physical phenomena or in solving purely mathematical problems, but not used in other areas of human activity. Another goal is to find analytical surfaces promising for application in architecture and mechanical engineering, which are still little known to architects and engineers. It has been established that, as before, designers take new analytical surfaces to implement their creative ideas from well-studied classes of surfaces of revolution, transfer and umbrella, minimal, ruled, wavy surfaces.
{"title":"Analytical surfaces for architecture and engineering","authors":"Mathieu Gil-oulbé, T. Daou, Ousmane Mariko","doi":"10.22363/1815-5235-2022-18-5-458-466","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-5-458-466","url":null,"abstract":"Geometers have proposed more than 600 analytical surfaces for implementation. The largest number of these surfaces is used in architecture and mechanical engineering. Although digital architecture and free form architecture are now increasingly influencing the design of long-span shell structures and curved buildings, the research and application of analytical surfaces continues on an increasing scale. The purpose of the research is to study the state of affairs in the application of analytical surfaces in the construction and engineering industries and to clarify the classes of surfaces that have found application in the study of physical phenomena or in solving purely mathematical problems, but not used in other areas of human activity. Another goal is to find analytical surfaces promising for application in architecture and mechanical engineering, which are still little known to architects and engineers. It has been established that, as before, designers take new analytical surfaces to implement their creative ideas from well-studied classes of surfaces of revolution, transfer and umbrella, minimal, ruled, wavy surfaces.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46884309","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 : 2022-12-15DOI: 10.22363/1815-5235-2022-18-5-467-474
S. Yakupov, Guzial Kh. Nizamova
Among thin-walled structures, including building structures and constructions, shells of complex geometry are effective in their rigidity and strength characteristics, which are also distinguished by architectural harmony. For a wider application of shells of complex geometry, it is necessary to reliably assess their stress-strain state. In this case, an integral part of the calculation is the parametrization stage of the median surface of shells of complex geometry. There are shells of complex geometry of canonical and non-canonical forms. For shells of non-canonical shape, the median surface cannot be defined by analytical formulas. At the same time, difficulties arise at the stage of specifying (parameterizing) the shape of the median surface. The task becomes more complicated when the shell fragment has a complex contour and one or more surface points have fixed coordinates. For building structures, this is, for example, the presence of additional internal supports. Information about the spline version of the FEM is presented. Some well-known parametrization methods are noted. The approach of parametrization of a minimal surface of a complex shape bounded by four curved contours and a given (fixed) coordinate of one inner point of the surface is considered. An algorithm for constructing a spatial network, as well as determining coordinates, metric tensor components and Christoffel symbols necessary for solving parametrization problems in the spline version of the finite element method is described.
{"title":"Surface parameterization complex geometry","authors":"S. Yakupov, Guzial Kh. Nizamova","doi":"10.22363/1815-5235-2022-18-5-467-474","DOIUrl":"https://doi.org/10.22363/1815-5235-2022-18-5-467-474","url":null,"abstract":"Among thin-walled structures, including building structures and constructions, shells of complex geometry are effective in their rigidity and strength characteristics, which are also distinguished by architectural harmony. For a wider application of shells of complex geometry, it is necessary to reliably assess their stress-strain state. In this case, an integral part of the calculation is the parametrization stage of the median surface of shells of complex geometry. There are shells of complex geometry of canonical and non-canonical forms. For shells of non-canonical shape, the median surface cannot be defined by analytical formulas. At the same time, difficulties arise at the stage of specifying (parameterizing) the shape of the median surface. The task becomes more complicated when the shell fragment has a complex contour and one or more surface points have fixed coordinates. For building structures, this is, for example, the presence of additional internal supports. Information about the spline version of the FEM is presented. Some well-known parametrization methods are noted. The approach of parametrization of a minimal surface of a complex shape bounded by four curved contours and a given (fixed) coordinate of one inner point of the surface is considered. An algorithm for constructing a spatial network, as well as determining coordinates, metric tensor components and Christoffel symbols necessary for solving parametrization problems in the spline version of the finite element method is described.","PeriodicalId":32610,"journal":{"name":"Structural Mechanics of Engineering Constructions and Buildings","volume":" ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46141505","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 : 2022-12-15DOI: 10.22363/1815-5235-2022-18-5-407-416
I. Belutsky, S. Kudryavtsev, Igor V. Lazarev
Steel-reinforced concrete spans in road bridges have been widely used since the late 1950s, in the configuration of large-span bridges built across significant water barriers. To date, the issue of the need to reconstruct such span structures, including those designed and built according to the project “43282 km” developed by TsNIIPSK, is becoming increasingly relevant. The authors analyze the stages of the production of works of a particular object, developed for the implementation of the entire complex of works on its reconstruction using the method of force regulation. The presented order of work was successfully implemented during construction of the bridge over Kabarga River in Primorsky Krai. This made it possible to preserve the existing structure of the span (main beams and braces), replacing the worn-out reinforced concrete slab with a new - metal orthotropic one, while ensuring that the conditions of strength and stability of the flexural-torsional shape of solid-walled beams are met, in the process of dismantling the existing roadway slab and constructing a new one. Considering that steel-reinforced concrete bridges are built across large water barriers and have a very significant cost due to their large length, reconstruction using existing supports can significantly reduce the cost of construction, so, the possibility of upgrading the existing steel-reinforced concrete span structure is, undoubtedly, relevant. Based on the structural and technological measures presented by the authors, it is possible to carry out and effectively implement work on the reconstruction of the existing steel-reinforced concrete bridges that do not fully meet modern requirements for load capacity and throughput.
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