The response of the structure and the joint operation of the elements emergency impacts, contact zone, will depend not only on the type of impact, but also on the structural design impactor, amount of motion, angle of of the building. The calculation of the transverse frame of a single-storey in-rotation, support displacement dustrial building, a multi-storey frame of a building with a ligament frame in the event of a vehicle collision, as well as the failure of the outer and inner columns of this building and a building with an incomplete frame in the event of an artillery shell impact is considered sequentially.

At first, we analyze the joint operation of the elements of a one-story industrial building with solid reinforced concrete columns, covered with reinforced concrete beams, on which are laid ribbed prefabricated floor slabs. The slabs form a rigid covering disk in the horizontal plane, but, as it is supposed, do not resist vertical displacements of individual beams in case of failure of one of their supporting columns.

Longitudinal reinforcement couplings, and particularly overlap-coupling, have various levels of ductility. This can influence the response parameters of reinforced concrete structures under dynamic loading by means of changes in the deformability of structures. The study investigates the resistance of reinforced concrete flexural members with overlap reinforcement coupling under dynamic loading in accidental design situations. It provides numerical modeling of reinforced concrete beams using the finite element method in a physically nonlinear three-dimensional formulation, taking into account the parameters of the bond-slip diagram. Based on the results of numerical modeling, the influence of longitudinal reinforcement overlaps couplings on the load-bearing capacity and ductility of reinforced concrete flexural members under dynamic loading arising in an accidental design situation has been assessed. It was established that the ultimate static load, determined based on energy balance, was 0.87 of the failure loads for both the flexural member with overlapping longitudinal reinforcement and the member with continuous reinforcement bars along its entire length. At the same time, the ratio between total and conventionally elastic deformations was 13.4 % higher for the structure with reinforcement coupling.

This study investigated the differences between reinforcement with St 37 steel bars and Damascus steel bars. The studied beams were made of high-performance concrete (HPC) reinforced with St 37 steel re-bars (SSR) of 10, 12 and 14, as well as 150-, 250-and 350-layers of Damascus steel rebars (DSR). The flexural strength tests results showed that HPC beams with 250-layers of DSR (with an average tensile strength of 857.27 MPa) can withstand an average flexural load of 52.19 kN, while HPC beams with SSR of 10 (with an average tensile strength of 485.34 MPa) can withstand an average of 69.52 kN. HPC beams with SSR, due to the ribbed structure of the steel rebars, are capable to withstand high flexural loads, whereas due to the absence of ribs on the surface of the DSR, HPC beams with it are capable to withstand low flexural loads, although the tensile strength of DSR is higher than that of SSR. The ribbed structure of the steel rebars is of fundamental importance for increasing the flexural strength, as it ensures the bond strength between the steel rebar and the concrete.

In 1749, L. Euler, building on the ideas of Jakob and Daniel Bernoulli, formulated beam theory in an exact formulation with the hypothesis of plane sections. Later, P.-S. Girard linearized the curvature, simplifying the derivation of analytical solutions, and B.P.E. Clapeyron expressed it in terms of derivatives of the deflection function. As a result, the Euler ± Bernoulli model split into two classes: the linear (classical) formulation with Girard’s curvature and the so-called "exact" geometrically nonlinear formulation with Euler ± Clapeyron curvature. This work demonstrates that the class of geometrically nonlinear problems is a methodological fallacy. The function y(x), traditionally interpreted as the deflection function, is in fact a mapping of a topological space onto a plane in the Cartesian system and describes the distance from the topological abscissa to the neutral axis of the deformed beam. The initial segment of the topological abscissa is nearly rectilinear, which justifies the use of the classical model for small deformations. However, for large deformations, even the "exact" curvature formula proves to be incorrect. A new force component ³ the restoring potential P ³ is introduced, which closes the system of equations and links the rotation angles to the external transverse load. The generalization of beam theory in rectilinear and curvilinear (topological) coordinate systems using a generalized variable i has revealed a deep connection between these computational spaces and enables the reconstruction of the exact geometry of the deformed beam based on classical Euler ± Bernoulli solutions. Thus, this work resolves the fundamental problem posed by Jakob Bernoulli (1694), establishing a generalized beam theory in which linearity and the hypothesis of plane sections are preserved throughout the entire range of elastic behavior.

During operation, crane structures are subject to multidirectional impacts: movement of the crane along the crane track, braking of the crane bridge directed along the crane rail, braking of the crane trolley directed perpendicular to the crane rail. This creates alternating stresses that can cause fatigue failure. In the elements of overhead crane beams and brake structures, fatigue cracks appear and gradually develop, which can ultimately lead to the complete failure of the structures. Another reason for the onset of the limit state of crane structures may be mechanical damage (wear of rubbing parts) and contact with an aggressive environment (corrosion). The aim of the work is to establish patterns of failure occurrence, study the influence of external and internal factors on reliability, establish quantitative characteristics and methods for assessing the reliability of crane structures. For this purpose, it is proposed to develop effective methods for calculating crane structures that have been damaged during operation, taking into account the specifics of the impacts on them and the properties of materials using CAE packages.