No abstract

This work is devoted to the study of the influences of various parameters on the bearing capacities of compressed reinforced concrete columns of varying flexibilities damaged during operation. Experimental tests of pilot samples were carried out, and results were analyzed on the basis of which it was established that significant longitudinal bending was observed in the direction of the x-axis. By analyzing the influences of the angle and depth of damage on the behavior and nature of the destruction in the experimental samples, three main destruction patterns were identified. An analysis of the experimental and statistical models showed that the greatest influences on the bearing capacity of the samples were the depth of the damage and the angle of the cut, and the effect of the height of the samples was virtually negligible. A model of calculation for the residual bearing capacities of compressed damaged reinforced concrete elements of different flexibilities was developed. The results of the comparison testify to the good coincidence of the theoretical values with the values obtained from the actual experiment (the difference of an average of no more than 29.8%), indicating that the proposed method can be applied in building practice.

Methods for determining the characteristic values of climate loads at the location of a building have been perfected. Based on comparative analysis, the method of levelling the values of climate loads with an exponential or triangular weight function is recommended. For four climate loads, appropriate equalization intervals are determined, ensuring the maximum amount of weather data taken into account, while maintaining their uniformity. In construction, the determination of the climate load is important for the location of the building. When prescribing building standards, the values of the climate load are determined according to the data of weather stations in relative proximity, which provides values within the limits of reliability. Such an approach can lead to an overestimation of the characteristic values of climate loads and consequently increase the consumption of the construction materials of the building or, in the opposite case, decrease the unnecessarily high-energy consumption to condition the space inside the building.

This work presents a proposed engineering method for calculating the bearing capacity of the supporting sections of continuous monolithic reinforced concrete tape beams, which combine pressed or driven reinforced concrete piles into a single foundation design. According to the mechanics of reinforced concrete, it is recommended to consider the grillage to be a continuous reinforced concrete beam, which, as a rule, collapses according to the punching scheme above the middle support (pile caps), with the possible formation of a plastic hinge above it. The justification for the proposed method included the results of experimental studies, comparisons of the experimental tensile shear force with the results of calculations according to the design standards of developed countries, and modeling of the stress-strain state of the continuous beam grillage in the extreme span and above the middle support-pile adverse transverse load in the form of concentrated forces. The work is important, as it reveals the physical essence of the phenomenon and significantly clarifies the physical model of the operation of inclined sections over the middle support. The authors assessed the influence of design factors in continuous research elements, and on the basis of this, the work of the investigated elements under a transverse load was simulated in the Lira-Sapr PC to clarify the stress-strain state and confirm the scheme of their destruction adopted in the physical model by the finite element method in nonlinear formulation. Based on the analysis and comparison of the experimental and simulation results, a design model was proposed for bearing capacity near the supporting sections of continuous reinforced concrete beams and high grillages that is capable of adequately determining their strength.

The article is devoted to studies about the stress-strain state and the residual bearing capacity of inclined sections of reinforced concrete beams with concrete damages in the compressed zone near support areas. The developed method of calculating the bearing capacity of the inclined sections of damaged beams is described. The numerical test of prototypes was performed in the LIRA-CAD 2017 software complex. A comparison of the results of laboratory tests, a numerical experiment and calculation results by the proposed method is shown. It is stressed that with an increase in the area of damage, the bearing capacity decreases. The nature of the change in the stress-strain state under the presence of damage is described. It is pointed out that in the damaged samples, there is an inclination of the neutral axis in the cross section of the element – it tilts, the neutral axis becomes, almost, parallel to the front of the damage.