Methods of mathematical modeling and urban space organization

The use of digital technologies and methods of mathematical modeling allows modern architects to design the cities that have their own unique style and harmoniously fit into the environment. It is necessary to widely introduce three-dimensional modeling methods into practice for more effective urban space creation and development

Calculation of shallow polymer shell taking the creep into account

In this paper, we obtain the equations allowing the calculation of shallow shells taking the creep into account under an arbitrary law of relationship between creep deformations and stresses. We also consider the methodology of calculation of polymeric membranes, the material of which is subject to a nonlinear equation of Maxwell-Gurevich

Side busking of the cantilever beam with narrow rectangular cross section

The problem of lateral buckling of a cantilever strip with a constant narrow cross section loaded with a concentrated force at the end of the span is considered. In the study of lateral buckling of beam energy method was used. For the case of load application in the center of gravity, the problem is reduced to a generalized secular equation. The relationship between the magnitude of the critical force and the position of the point of application of the load. A comparison of the results obtained by the authors with an analytical solution using infinite series and a numerical iterative method is shown

Calculation of shallow polymer shell taking the creep into account

In this paper, we obtain the equations allowing the calculation of shallow shells taking the creep into account under an arbitrary law of relationship between creep deformations and stresses. We also consider the methodology of calculation of polymeric membranes, the material of which is subject to a nonlinear equation of Maxwell-Gurevich

Features of compressed rods calculations with account of initial imperfections and creep effects

The article presents solutions to the problem of rod buckling, taking into account creep effects. Trigonometric series, the finite difference method in combination with the programming language MATLAB, as well as the finite element method in the ANSYS software package were used in the solutions. The behavior of the rods is researched for two types of relations between strain and stress during creep, with strains in an explicit and implicit form. When solving, the criterion of initial imperfections with their different values is used, as well as the tangential-modular theory. The results obtained for the two creep models are compared. The conclusion is made about the accuracy of the results of calculations in ANSYS with the presence of a combination of geometric and physical nonlinearity for various creep models

Creep calculation for a three-layer beam with a lightweight filler

In the article the technique of calculation of a three-layer beam with a lightweight filler taking into account the creep of the middle layer is given. The problem reduces to a second-order differential equation, which is solved numerically by the method of finite differences. An example of a calculation is presented for a hinged at the ends beam under the action of a uniformly distributed load. The linear Maxwell-Thompson equation is used as the creep law. Solution was performed in software package Matlab

DETERMINATION OF CONCRETE RHEOLOGICAL PARAMETERS USING NONLINEAR OPTIMIZATION METHODS

The article proposes a method for processing concrete creep curves based on the nonlinear equation of V.M. Bondarenko. The experimental data of A.V. Yashin is used. The problem of finding rheological parameters and the nonlinearity function is posed as a nonlinear optimization problem. The objective function represents the sum of the squared deviations of the experimental values of the creep strain from the theoretical values for all creep curves for one concrete at different stress levels. The minimum of the objective function is found using the interior point method, the surrogate optimization method, the pattern search method, the genetic algorithm, and the particle swarm method. It has been established that the first of these methods has the greatest efficiency. The proposed approach provides high quality approximation of experimental curves at all stress levels. It is shown that for concrete the nonlinearity of creep deformations is more pronounced than the nonlinearity of instantaneous deformations, and the same function cannot be used to describe these two types of nonlinearity

Metal structures diagnosis by truncated cone indentation

The method of the steel structures diagnosis is considered with nondestructive test by truncated cone indentation. Recently, great interest in the nondestructive evaluating of the steel mechanical properties at real structures is developed in many applied problems. Dynamic indentation method is one of the most effective because of compatibility and accuracy. For this purpose static and dynamic problem of axisymmetric elastic-plastic truncated cone indentation is solved and the results are compared with finite element analysis and experimental data. The method of nondestructive evaluating of mechanical characteristics is suggested and devise of the realization of the method is tested at real structures

Calculation of orthotropic plates for creep taking into account shear deformations

A system of differential equations is obtained for calculating the creep of orthotropic plates taking into account the deformations of the transverse shear. The basic hypothesis is a parabolic change in tangential stresses over the thickness of the plate. An example of the calculation is given for a GRP plate hinged on the contour under the action of a uniformly distributed load

Harmony and disharmony as the architectural appearance features of the city

Architecture in the world obeys the laws of symmetry and asymmetry, harmony and disharmony, and, of course, the principles of the golden section. The use of digital technology and innovation allows modern architects to design the structures that have a harmonious style and harmoniously fit into the environment. It is necessary to widely introduce the three-dimensional modeling methods into practice for more effective modern cities’ architectural appearance creation