Systems of Approximating Functions when Using Variational Methods for Calculating Thin-Walled Building Structures

The question of the use of approximating functions in the calculation of thinwalled building structures is investigated and the requirements that they must satisfy are analyzed. A rule is formulated that allows one to distinguish between the principal boundary conditions and natural ones. It is show...

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Main Author: Vladimir V. Karpov
Format: Article
Language:English
Published: Peoples’ Friendship University of Russia (RUDN University) 2025-07-01
Series:Structural Mechanics of Engineering Constructions and Buildings
Subjects:
Online Access:https://journals.rudn.ru/structural-mechanics/article/viewFile/45220/25134
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author Vladimir V. Karpov
author_facet Vladimir V. Karpov
author_sort Vladimir V. Karpov
collection DOAJ
description The question of the use of approximating functions in the calculation of thinwalled building structures is investigated and the requirements that they must satisfy are analyzed. A rule is formulated that allows one to distinguish between the principal boundary conditions and natural ones. It is shown that the approximating functions must satisfy the principal boundary conditions, while the natural boundary conditions are included in the equilibrium equations and are satisfied automatically when solving a boundary value problem. The accuracy of their fulfillment depends on the accuracy of the solution of the problem itself. An example shows what errors can result from the use of approximating functions that satisfy the specified boundary conditions, but do not satisfy the completeness conditions. Some systems of functions for which the completeness condition in the energy space has been proven are considered. Using the example of Legendre orthogonal polynomials, a technique is given for forming approximating functions that satisfy the specified boundary conditions and the completeness conditions of a system of functions. The efficiency of using the obtained approximating functions in solving boundary value problems using the Galerkin method is shown.
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spelling doaj-art-dbf8c3dfed1f420db09a00d0cbe8e7fc2025-08-20T03:15:27ZengPeoples’ Friendship University of Russia (RUDN University)Structural Mechanics of Engineering Constructions and Buildings1815-52352587-87002025-07-0121213815410.22363/1815-5235-2025-21-2-138-15421078Systems of Approximating Functions when Using Variational Methods for Calculating Thin-Walled Building StructuresVladimir V. Karpov0https://orcid.org/0000-0001-7911-4067Saint Petersburg State University of Architecture and Civil EngineeringThe question of the use of approximating functions in the calculation of thinwalled building structures is investigated and the requirements that they must satisfy are analyzed. A rule is formulated that allows one to distinguish between the principal boundary conditions and natural ones. It is shown that the approximating functions must satisfy the principal boundary conditions, while the natural boundary conditions are included in the equilibrium equations and are satisfied automatically when solving a boundary value problem. The accuracy of their fulfillment depends on the accuracy of the solution of the problem itself. An example shows what errors can result from the use of approximating functions that satisfy the specified boundary conditions, but do not satisfy the completeness conditions. Some systems of functions for which the completeness condition in the energy space has been proven are considered. Using the example of Legendre orthogonal polynomials, a technique is given for forming approximating functions that satisfy the specified boundary conditions and the completeness conditions of a system of functions. The efficiency of using the obtained approximating functions in solving boundary value problems using the Galerkin method is shown.https://journals.rudn.ru/structural-mechanics/article/viewFile/45220/25134approximationgalerkin methodprincipal boundary conditionsnatural boundary conditionscompleteness of functionslegendre polynomialsconvergence
spellingShingle Vladimir V. Karpov
Systems of Approximating Functions when Using Variational Methods for Calculating Thin-Walled Building Structures
Structural Mechanics of Engineering Constructions and Buildings
approximation
galerkin method
principal boundary conditions
natural boundary conditions
completeness of functions
legendre polynomials
convergence
title Systems of Approximating Functions when Using Variational Methods for Calculating Thin-Walled Building Structures
title_full Systems of Approximating Functions when Using Variational Methods for Calculating Thin-Walled Building Structures
title_fullStr Systems of Approximating Functions when Using Variational Methods for Calculating Thin-Walled Building Structures
title_full_unstemmed Systems of Approximating Functions when Using Variational Methods for Calculating Thin-Walled Building Structures
title_short Systems of Approximating Functions when Using Variational Methods for Calculating Thin-Walled Building Structures
title_sort systems of approximating functions when using variational methods for calculating thin walled building structures
topic approximation
galerkin method
principal boundary conditions
natural boundary conditions
completeness of functions
legendre polynomials
convergence
url https://journals.rudn.ru/structural-mechanics/article/viewFile/45220/25134
work_keys_str_mv AT vladimirvkarpov systemsofapproximatingfunctionswhenusingvariationalmethodsforcalculatingthinwalledbuildingstructures