In the study, experimental and theoretical studies were carried out to assess the influence of the shapes of dents in the tank wall on the stress-strain state of the defect zone. By testing fragments of a cylindrical tank, it was found that the most appropriate expression is (5), which could take into account the leaching of the tank wall, resulting in a decrease in the stress concentration index. At the same time, during theoretical studies in this paper, it was found that polynomials determined the stress concentration coefficient, where the obtained analytical expression data were compared with the data determined numerically in the ANSYS program, and it was found that the spread was from 2% to 10%. According to the results of a numerical study of the stress-strain state of the dent zone in the tank wall, graphical dependences of the stress concentration coefficient on the dimensionless depth of the dent for various values of the dimensionless radius of the dents and do not exceed 2% of the indicators that are obtained. At the conclusion of the experimental and numerical studies, a conclusion was made about the degree of influence of the geometric dimensions of the dents on the stress concentration index.

In the study, experimental and theoretical studies were carried out to assess the influence of the vertical mounting joint zone of the tank on the stress-strain state of the defect zone. Thus, experimental tests of models of a tank wall fragment with an imperfection of the mounting joint evaluated the stress-strain state of the mounting joint zone and established the dependence of the stress concentration in the joint zone on the deflection, the width of the zone and the thickness of the tank wall. It is shown that with a 50 mm bending boom, the annular stresses increase by 1.3 times than with a 30 mm bending boom and the meridional stresses increase by 1.16 times. The same nature of the increase is observed with the stress concentration indicator. By numerical analysis of the stress-strain state of tanks with joint imperfections in the ANSYS medium, the stress-strain state of the tank is estimated for various values of the joint bending parameters ς and ξ. The dependences of the stress concentration coefficient on the geometric dimensions of the imperfection, radius and thickness of the tank wall are also obtained. From the results of calculating the stress concentration coefficient, with an increase in the dimensionless parameters ς and ξ, the values of the stress concentration coefficient K_σ increase by 1.35 times. As a result of the calculations, an interpolation polynomial (5), approximating the stress concentration coefficient K_σ, is obtained, which can be used to estimate the strength, durability and residual resource of the tank. In addition, the obtained results can be used to normalize the limiting dimensions of the imperfection of the joint and to establish the values of the coefficient, taking into account the peculiarities of the work of structures at stress concentrations.

The paper presents the results of experimental studies of the features of the operation of prestressed shells, taking into account the various structural parameters of the prestress. It is established that when the winding angle changes from perpendicular to the shell axis to 75° and 65°, the circumferential stresses decrease 1.4 times and 1.2 times, respectively, and the axial stresses increase five and three times, which are two and four times lower than the circumferential, from which it can be concluded that the reduction in the winding angle to the longitudinal the axis of the shell has a positive effect on the stress state of the structure. The study also found that with an increase in the diameter of the winding wire from 1 to 2 mm and a change in the winding angle, the same nature of the stress distribution is observed, but the values of the stress state parameter change, so the efficiency increases up to 25% due to an increase in the winding thickness, depending on the pitch, angle and thickness of the winding, which favorably affects the strength and the bearing capacity of the structure as a whole by increasing the value of the stress state parameter. Thus, the results of the analysis will allow us to use in more detail the possibility of controlling the stress–strain state of the prestressed shell by changing the design parameters, and the results obtained can be used in design or construction, as well as when increasing the strength characteristics of the structure, which allows us to create a high-tech design optimal for these operating conditions, which can positively complement the studies conducted earlier in this direction.

Precise meanings of thermophysical processes taking place in air gaps have decisive importance in composite cladding structure systems’ calculation and modeling. The climatic load conditions in Kazakhstan can significantly affect the microclimate of premises in general. In this work, a review study is carried out to obtain the relevant scientific literature on enclosing structures with air gaps under various climatic conditions. The review mainly covers research institutes from Sweden, Norway, France, Saudi Arabia, Russia, and China. On the issue of the air gap parameter’s influence on thermophysical processes, 16 papers were analyzed, and on the issue of air infiltration, 12 papers were analyzed. However, the review shows a lack of research in this area under various climatic conditions. At the same time, experience has shown that the principle of multilayer protection from climatic influences creates a favorable microclimate in buildings, but due to a possible temperature drop, wall structures made of composite building materials can be quite favorable under some conditions, and under others they may be less favorable. Therefore, working out a new energy-saving design with air gaps for climatic conditions with large temperature fluctuations during summer and winter is an urgent task.

In this work, two new face structures of the open-air protection fence were investigated, where a method was proposed for analyzing the condensation of water vapor in the protection fence to search for a condensation zone. Another method for calculating the amount of condensed vapor in a multiwall protection fence with closed gap spacings was proposed. The analytical results illustrated that the magnitude of the range of temperature variations of the worked-out structures with gap spacings and without heat-reflecting screens was 7.14% lower, while the existence of heat-reflective screens reduced this value to 27.14%. The investigation of the water vapor transmission magnitude demonstrated that the steam permeability strength of the interior side and retaining walls of the developed buildings amounts to the standard one, while the usage of a locked air space with a thermo-reflective panel allows the movement of the appropriate condensing region over the external face of the fencing. Mass analysis of the precipitated vapor during the heating time of 1 m² of the retaining wall showed that in face structures in closed gap spacings with heat-reflective screens, the mass of the precipitated vapor was 24.8% greater relative to that of the face without heat-reflective screens. Moreover, the examination of the absence of distillation in the oxygenated gap spacing proved that, in the gap spacing in the considered face structures, the condensate does not fall out such that there is no aggregation of humidity according to the annual balance. Furthermore, the drying time of the face structure with heat-reflecting screens was 17.9% longer than that of the traditional one. The research results can complement the works performed earlier by the authors, as well as be applied in the engineering and construction of buildings to save thermal power, considering the climatic features of the development region.

This article presents one part of a study on the dynamic deformation and fracture of sections of steel gas pipelines with an external crack-like defect under the action of internal pressure. This work was performed on the basis of finite-element simulations using a cylindrical shell model executed by ANSYS-19.2 on the example of the section of the steel gas pipeline “Beineu–Bozoy–Shymkent” in the Republic of Kazakhstan. The propagation of the incipient crack-like defect along the pipeline and the resulting dynamic fracture in its tip area were investigated. The options of pipeline loading by working and critical internal pressure were both considered. It was found that, within the time of 1.0 ms, the formed crack expanded in the circumferential direction up to the maximum value, which depended on the value of the internal pressure. A further growth of cracks occurred along the longitudinal direction. At the operating pressure, the initial length of the crack increased by a factor of 5.6, while the equivalent stresses increased by a factor of 1.53 within 3.5 ms. Within the time of 3.75 ms, the equivalent stresses stopped growing due to the gas decompression. Specifically, there was a stop to the crack growth along the longitudinal direction. Vice versa, at the maximum pressure, the pipeline fracture did not change qualitatively, while at the time of the process, it decreased up to 3.5 ms. The finite-element results of the stress–strain state and pipeline fracture in the crack tip area at the working pressure showed that, within the time of 1.0 ms, the distance between the crack walls reached 23 mm at the free edge. Conversely, within the time periods of 2.25 and 3.5 ms, it increased two and three times, respectively. The crack elongation in the longitudinal direction occurred 5.8 times with time. Together, within the time of 3.5 ms, the equivalent stresses increased twice, after which the growth of the crack stopped due to the gas decompression. Moreover, studies on the growth of the crack-like defect in its tip area at the maximum pressure showed that additional considerations on the pressure on the crack edges led to an increment of 3.6% of the crack length. The results of this work can be used for the development of measurements for operating gas pipelines in the field of structural reinforcement.