The stress values at the crack tip in bending reinforced concrete beams are considered. The stress state is analytically determined with an initial and propagating crack. Equations of the equilibrium of a part of the beam cut along the crack line are compiled. These equations are reduced to a system of two nonlinear algebraic equations using the plane-sections hypothesis. The equations determine the stress zone’s height and the nominal stress at the crack tip for a beam with an initial crack and the crack length. The rest of the stress state parameters are expressed regarding the zone stress height and the nominal stress or crack length. The same equation system determines the external moment starting from which the crack length increases. The analytical method for determining the stress intensity factor (SIF) with an initial and growing crack in bent reinforced concrete beams is proposed. The method is based on the assumption that the size of the stress concentration zone at the crack tip is determined by the equality of the nominal and local stresses at the end of this zone. The method determines the value of the external moment starting from which the crack length increases. The stress zone’s size is determined by the coincidence of the local stress with the nominal stress. The same problem is solved in a three-dimensional formulation by the FE method, considering the stress field’s peculiarities at the crack tip. The calculation results coincide with the analytical solutions.

This article analyzes the causes of the collapse of a high-rise chimney in Petropavlovsk. A study of the factors of long-term (over 60 years) operation of a high-altitude (H=150 m) chimney was carried out. The analysis of the constructive solution of the pipe was carried out, and the study of the operating conditions was performed. To theoretically assess the technical condition and stress-strain state factors (SSS) of the collapsed chimney, automated verification calculations were carried out based on the actual parameters and characteristics obtained during the last technical inspection. An automated verification calculation of SSS factors determining the bearing capacity of an object (its strength, rigidity, reliability, and durability) has been performed. Theoretically, the physical wear of the object has also been carried out. Based on the study of the available technical documentation and conducting a continuous, detailed instrumental examination of the facility, the expert organization established the significant causes that led to the pipe accident.

For the first time in research practice, the performance of pile foundations is examined in conjunction with a comprehensive geotechnical assessment of soil conditions during construction on problematic territories. The study is based on the results of technical inspections and aims to identify the causes of deformations in the load-bearing structures of buildings. Particular challenges arise in the development of areas located on the sites of former quarries that were later backfilled with loose, uncompacted soils. The analysis revealed significant errors made during geotechnical investigations, which resulted in unacceptable settlements and structural damage. These findings indicate the need to revise existing design approaches and to strengthen quality control over geotechnical surveys. This issue becomes particularly relevant in the context of the transition to Eurocode-based design, which requires a more accurate adaptation of international standards to local geological conditions.

The paper presents an algorithm for calculating key statistical parameters, including correlation dependences, correlation coefficients, and a method of checking the presence of a linear dependence. A quadratic regression equation is obtained, regression curve graphs are constructed, distribution functions and probability densities with the procedure for their normalization are calculated. The main statistical parameters of random variables are also calculated: mathematical expectation, variance, standard deviation, and quantiles of various levels. The proposed regression analysis algorithm can be used to assess safety and reliability of building structures, which allows analyzing their operation in a probabilistic form. Based on the theoretical and applied results of the work, prospects are opened for further development of probabilistic analysis methods for safety of construction projects as a whole, taking into account their complex structure and interaction of various structural elements.

Technobius is a peer-reviewed open-access journal that publishes original research articles of experimental and technical nature in the field of construction and building materials