Determination of the degree of impact for compressed-bending elements taking into account physical and geometric nonlinearity from conventional means of destruction

Introduction. Currently, various types of conventional means of destruction (CMD) attack buildings and lead to varying uses: civil and industrial. CMD often damages individual building structures, such as slabs, columns, beams, etc. Hence, assessing the category of technical condition (TC) of building structures is an urgent task for survey engineers. This problem is solved by introducing the data obtained from the survey results into the verification calculation. The subject of the study is the method of strength calculation of damaged building structures from CMD using the example of a rod element with a compressive-bending stress-strain state (SSS). The purpose of the study is to determine the degree of impact of the CMD of the specified element, taking into account the various nonlinearities of the material.

Materials and methods. The paper discusses a method of numerical calculation for beyond design impact from conventional means of destruction, which takes into account not only the features of the physical and mechanical characteristics of building materials, but also the physical and geometric nonlinear work of the building structure being examined. The physical nonlinearity of reinforced concrete is considered in this article on the basis of the requirements of building codes of the Russian Federation, such as СP 63.13330 and the Manual for СP 63.13330. During the numerical calculation, the following methods are used: the method of initial parameters and the method of simple iterations (or the numerical iteration method). The initial parameters method determines the linear and angular displacements of the rod. The iteration method is used to solve a system of equations, which, with a given accuracy, determines the value of the next approximation based on the approximate value.

Results. The proposed method for determining the forces in the cross-section of a bar compression-flexural element and the method of initial parameters make it possible to obtain reasonable results of numerical calculations taking into account residual deformations and the deformed model of concrete and steel.

Conclusions. The developed method of strength calculation is a verification calculation of existing building structures. For simplicity and convenience of performing verification calculations, the algorithm of this technique is automated in the language VBA (Visual Basic for Applications).

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