The results of experimental studies examining the performance of reinforced concrete slabs under low-velocity impact loads are presented. Im-pact loads were generated on specimens using a freely falling weight, striking the specimens at their midpoint. These tests showed that the impact behavior of the slabs differs significantly from their static behavior. Displacement pro-files and force distributions change significantly due to the high inertial forces during impact. Test data were collected using well-equipped instrumentation to understand the behavior of reinforced concrete slabs under impact loads. This data can be used in further research and serve as a starting point for the development of analysis and design methods for impact loads. Studying the behavior of reinforced concrete slabs subjected to impact loads requires a well-designed experimental program accompanied by numerical and analyti-cal studies. Experimental studies are crucial for validating analytical and nu-merical methods. This study investigates the behavior of reinforced concrete slabs tested under various impact loads and compares the results with the be-havior of identical specimens tested under static loads.

The article presents the main provisions of the method for calculating the residual life of a reinforced concrete beam on a soil base under conditions of nonlinear and non-equilibrium deformation under dynamic loading with conditions of long-term operation. The process of deformation is considered from a phenomenological position based on the method of integral assessments. An estimated estimate of the residual life during long-term operation of a reinforced concrete beam on a non-linearly deformable soil base is presented, taking into account corrosion damage in different periods of operation in order to ensure safety. The calculation of the residual life of a rein-forced concrete beam at different periods of long-term operation is given. The proposed calculation method considering the real properties of materials under conditions of external deformation and, along with taking into account the residual life, will make it possible to obtain safer and more economical structures.

The present work contains a proposal according to which the internal force (bending moment) in iron-concrete beams is determined without prestressing the longitudinal armature, depending on the opening width of normal cracks. The force is determined by the formula, which was obtained by converting the existing formula of the current joint venture to calculate the opening width of a normal crack. In this case, a coefficient is introduced into the proposed formula. 

Monolithic concreting works are carried out year-round. One of the challenges is construction work in the winter season, specifically the effect of subzero temperatures on the concrete hardening process in the structure. This is because the mixing water that has not reacted with the cement freezes, expanding in volume by 9 %. As a result, internal stresses arise in the concrete, leading to a disruption of its structure. This article presents the problem of determining temperature and mass fields in a flat monolithic reinforced concrete structure during winter concreting. The initial heat and mass transfer equations and boundary conditions are presented, allowing for the modeling of eight real-world situations that arise during concreting. During operation, building and structural systems may be subjected to various types of accidental actions, creating a risk of complete or partial collapse.

The paper considers the problem of local failure of a reinforced concrete slab subjected to impact by a heavy steel projectile. This problem is of practical importance in the design and safety assessment of protective structures, including facilities in the nuclear industry and other special-purpose structures. The relevance of the study is determined by the need for computationally efficient models capable of accounting for the influence of reinforcement on penetration parameters and damage patterns under moderate velocity impact loading. The aim of the study is to develop and justify a mixture-based mathematical model of reinforced concrete for predicting local damage and penetration depth. A numerical approach is used in which reinforced concrete is represented as a homogeneous two-phase medium reflecting the combined action of the concrete matrix and reinforcing steel. The model is calibrated using published experimental data for the impact of a composite steel projectile with a mass of about 330 kg and a velocity of about 30 m/s on a reinforced concrete slab. The calculations made it possible to determine the kinematic parameters of projectile motion, penetration depth, and the main features of target failure. The results show that the proposed model reproduces the main characteristics of reinforced concrete slab perforation with satisfactory accuracy and can be used for engineering assessment of the impact resistance of reinforced concrete structures.