卷 21, 编号 3 (2025)

A numerical method for analyzing fast-flowing dynamic behavior of a system of bodies during their contact interaction is investigated. The research method is based on the analysis of solution convergence when the finite element grid is condensed and the time step is reduced. The algorithm and the corresponding computer program were developed by the authors. The problem is considered in a geometrically and physically nonlinear formulation, large elastic and plastic deformations are considered. The finite element method is used. The simplest triangular finite element with a linear displacement field is used. The initial grid of finite elements is assumed to be uniform; in the process of plate deformation, it is greatly modified, since large displacements are simulated. Plane strain is considered. The criterion for the onset of plastic shear is shear stress achieving a certain limit set in the conditions of the problem. The relationship between strain and stress implemented in the program implies taking into account the strain history of the material at a given point, and not just the current value of strain. The model also allows to consider unloading, if such is the case. The calculation model is focused on the correct consideration of geometry with large displacements and rotation angles, allows consideration of free flight of the components of the model, their contact interaction. In terms of integrating the equations of motion, the program relies on an explicit calculation scheme with Adams extrapolation. The application of the described algorithm is based on the example problem of a flying short beam (plate) hitting a rigid stop. The example considers impact interaction, rebound from the stop, and free flight of the vibrating beam. The elastic and inelastic behavior of the material is compared. The wave nature of the solution is demonstrated. The example is comprehensively analyzed, in particular, convergence is investigated when the grid is doubled and the time step is reduced. The maximum number of finite elements is 204800. The numerical algorithm has a number of features: constant stress acquisition and storage for planes oriented along the fixed global axes, and the possibility of shear deformation at any of the critical planes. It is concluded that it is impossible to achieve convergence for accelerations when the grid is condensed, and it is concluded that this impossibility is not fatal for the method. As an alternative, it is proposed to determine the acceleration of the center of mass of the beam or any fragment of the model.

A cable of finite stiffness is a model for a wide range of load-bearing structures, such as large-span suspended roofs of public and industrial buildings. At the same time, a new class of engineering structures has appeared relatively recently, designed to create an insurmountable physical obstacle to unauthorized movement of vehicles. The main elements that ensure the overall strength and rigidity of such structures are ring-shaped steel sections, which resist lateral impact. In this regard, there is a need to solve problems of optimal design of these elements. The objective of this study is to create a method that allows setting and solving the designated problems. The developed method is based on single-criterion multiparameter conditional optimization, the Bubnov-Galerkin method, as well as integral and differential calculus of multivariate functions. Verification of the proposed modeling technology is carried out. Discrepancies in the values of the adopted criteria for assessing the accuracy of the obtained results stay within the permissible errors in solving engineering problems. Using the developed method, the studies were conducted and the influence of the ratio of the internal to external diameter of the ring section on the weight and size characteristics, as well as the behavior of the bending-rigid cable under the action of a short-term dynamic load was revealed.

Large-span roof structures allow creating spacious rooms without using intermediate supports, which is important for a flexible planning system of industrial and public buildings. Typically, such structures are made of metal or reinforced concrete trusses or arches. The object of the study is a new ridged structure of a wooden plank roof panel for industrial buildings with spans of 24 and 30 m. The width of the panel without rafter structures is 2.4 m. The connection of individual boards and elements with each other in the panel is provided by nails and bolts, which compares favorably with glued wooden structures. It is possible to assemble the structure directly on the construction site. There is no need to deliver a large-scale product to the installation site. The article provides a detailed analysis of design solutions, presents calculation methods, as a result of which it is determined that the proposed structure meets the condition of bending rigidity. A simple to manufacture and to install system is described, based on the use of wooden boards and panels, which provide the nec-essary overall stability of the structure, making it an attractive option for use in various climatic regions. The results of the studies confirm the high potential for further implementation of such technology in real design practice.

This study investigates the seismic vulnerability of non-code-compliant reinforced concrete (RC) buildings compared to code-based structures. The research uses linear elastic and nonlinear pushover analyses (NPA) to evaluate critical seismic performance parameters such as natural periods, mass participation, base shear, capacity curve, ductility ratio, overstrength factor, collapse mechanics, and nonlinear hysteretic damping (NHD). Structures designed following standards like NBC 205 (old), RUD 205 new, and Indian standard IS 1893 are analyzed against non-code-compliant building samples (NES1-NES6) to highlight performance gaps. The findings reveal that code-compliant buildings demonstrate significantly higher seismic resistance, greater flexibility, effective earthquake energy dissipation, higher ductility, overstrength factor, and base shear capacity. Non-code-compliant buildings often exhibit soft-story failure, with initial damage observed in the columns, highlighting their vulnerability during seismic events. Meanwhile, code-compliant RC buildings (RUD) designed with seismic principles demonstrate better seismic performance, adhering to the “strong column, weak beam” philosophy and superior strength-to-capacity ratios, higher overstrength factors, and enhanced ductility ratios, highlighting their resilience under seismic loads. The results conclude that addressing the code provisions ensures earthquake-resistant buildings with warranted ductile behavior for structural systems, enabling the achievement of the intended collapse mechanism.