Introduction.

The author solves a number of problems, including the substantiation of the required reliability level for steel-concrete beams in a reconstructed building, design parameters applicable to steel-concrete beams, use of probabilistic methods in the reliability assessment of steel-concrete beams, and reliability assessment of steel-concrete beams.

Materials and methods.

The engineering data, used in the reliability analysis, included steel beam examination and testing results, obtained by the Koucherenko Central Research and Development Institute of Steel Structures in 2017. The analysis was performed for the cases that took account of or failed to take account of the behaviour of a cast-in-plaсe reinforced concrete floor slab. A method of statistic simulation has proven that the probability values of snow loads set for Moscow by Construction regulations 20.13330.2016 are far below the true ones. This discrepancy reduces the reliability of the contour beams of the construction facility analyzed in this article.

Results.

B-12, B-45, B-49 and B-61 types of beams were used to compare the testing results with probabilistic calculations. Selected calculation results are provided in the article. An 8 mm deflection, caused by the temporary design load of 2.4 kN/m2ensures the normal operation of a structure with a probability of 0.9973.

Conclusions.

A comparison between experimentally and analytically obtained deflection values has proven that the design model must have steel-concrete beams, rather than steel ones. Whenever a building structure is designed, its reliability level must be identified. The reliability of structures, having any criticality rating, depends on the values of the resistance probability in terms of their construction materials and the loads applied to them. Contour steel-concrete beams comply with the technology requirements and reliability values pre-set in the project documentation. Calculation results are validated by their convergence with the experimental data. Probabilistic methods should become a must in structural design. This measure can reduce the risk of failure or cut project costs.

Introduction.

Today thin-walled structures are widely used in the construction industry. The analysis of their rigidity, strength and stability is a relevant task which is of particular practical interest. The article addresses a method for the numerical analysis of stability of an axially-compressed i-beam rod subjected to the axial force and the bimoment. An axially compressed i-beam rod is the subject of the study.

Materials and methods.

Femap with NX Nastran were chosen as the analysis toolkit. Axially compressed cantilever steel rods having i-beam profiles and different flexibility values were analyzed under the action of the bimoment. The steel class is C245. Analytical data were applied within the framework of the Euler method and the standard method of analysis pursuant to Construction Regulations 16.13330 to determine the numerical analysis method.

Results.

The results of numerical calculations are presented in geometrically and physically nonlinear settings. The results of numerical calculations of thin-walled open-section rods, exposed to the axial force and the bimoment, are compared with the results of analytical calculations.

Conclusions.

Given the results of numerical calculations, obtained in geometrically and physically nonlinear settings, recommendations for the choice of a variable density FEM model are provided. The convergence of results is estimated for different diagrams describing the steel behavior. The bearing capacity of compressed cantilever rods, exposed to the bimoment, is estimated for the studied flexibility values beyond the elastic limit. A simplified diagram, describing the steel behaviour pursuant to Construction regulations 16.13330, governing the design of steel structures, is recommended to ensure the due regard for the elastoplastic behaviour of steel. The numerical analysis method, developed for axially-compressed rods, is to be applied to axially-compressed thin-walled open-section rods. National Research Moscow State University is planning to conduct a series of experiments to test the behaviour of axially-compressed i-beams exposed to the bimoment and the axial force. Cantilever i-beams 10B1 will be used in experimental testing.

Introduction.

The article addresses background gamma radiation in residential premises of apartment buildings in Vladivostok. This study is based on earlier research undertakings focused on the sick building syndrome (SBS), which proves its high relevance. The research is focused on the intensity of background gamma radiation in the residential premises of apartment buildings in Vladivostok. New data obtained in the course of the field experiments, the scale of their analysis, the coverage of substantive issues concerning radiation intensity and its monitoring in residential buildings guarantee the novelty of this research project. These findings also have a practical value that deals with environmental safety.

Materials and methods.

Onsite examinations were conducted in the form of background gamma radiation measurements taken in versatile apartment buildings, built at different times and made of different materials.

Results.

This section contains analytical information about the lack of influence of the location of apartment buildings on background radiation inside the apartments examined within the framework of this research project. Measurement results represent a range of values depending on construction materials used. Principal regularities, derived from the measurement results, are based on the time of operation of residential buildings, which is of practical importance.

Conclusions.

Patterns of influence of building parameters on background radiation inside apartments allow to assess the condition of residential buildings. Background radiation information can be entered into BIM databases and used to formulate the approach to the design of buildings and urban infrastructure so that they were focused on their residents and users. Background radiation research findings, entered into the database and contributed to design algorithms which are customized to the needs of urban residents, will enable designers to project the overall quality of the living environment encompassing the built environment analyzed in this article and other nearby buildings and structures located in Vladivostok.

Introduction.

This work is devoted to study the microbiological composition of the air 110 dwellings in the city of Vladivostok and the assessment of the impact of various factors on the microbiological condition of premises. The study is aimed at obtaining information about the real sanitary and hygienic conditions of the exploited residential area and identifying patterns of changes in environmental indicators from design decisions, building parameters and conditions of its operation. Research statistics are the result of field research with laboratory processing of the samples obtained. The relevance of scientific work also lies in the possibility of further factor analysis and verification of sanitary norms and rules with the practice of real design and operation of residential buildings.

Materials and methods.

Surveys were conducted on the basis of air sampling with subsequent assessment of the content of bacteria in the air of apartment buildings of different types, built at different times from different materials.

Results.

The section presents analytical data on the content of three main groups of bacteria in the air of residential premises located on the territory of Vladivostok. Based on the accumulated data, a comparative analysis was carried out to establish a correlation between the number of microorganisms in the air and the city area, the type of building material of the house, the density of apartment occupancy, and the presence of pets.

Conclusions.

Data on the influence of apartment occupancy density on the sanitary and microbiological situation were obtained. The assessment of the influence on the density of microbiological contamination of such factors as: the presence of pets, the type of building materials from which buildings are built, as well as the territorial location of the surveyed apartments.

Introduction.

Forensic structural engineering dates back to the late 20th century. Since then its theoretical and methodological fundamentals have been developed, and considerable practical experience has been accumulated. Nowadays, it is one of the most in-demand type of expert investigations performed in the course of judicial proceedings in Russia; therefore, it has boosted a significant inflow of specialists into forensic investigation organizations. At present, their total staffing exceeds ten thousand specialists. However, the professional training of forensic engineering experts is often heavily and rightly criticized by investigators, judges, and parties to judicial proceedings, defending their legitimate interests. The ever growing number of forensic expert investigations, ordered by the courts, and the growing complexity of tasks to be tackled by experts, have pre-determined the need for an effective expert training system, so that the qualification of experts could meet the rising demands of present-day court proceedings. The objective of this study is to develop the basic principles of this system.

Materials and methods.

This article is based on the assumption that the special features of activities, performed by forensic experts, determine, to a great extent, the essential principles of effective teaching of this discipline, as well as the major problems arising in the course of student training. The authors describe a combination of didactic methods (oral, printed and verbal, illustrative methods, etc.), teaching techniques and tools used to address these problems.

Results.

A coherent overview of features of a forensic structural engineering investigation (FSEI), including the procedural nature of its performance, the predominantly regulatory character of forensic investigations, as well as the practical value of FSEI findings substantially improve the efficiency of training highly qualified specialists. The statistics indicate that over 99 % of students can successfully complete training programs.

Conclusions.

A comprehensive, substantive procedural approach to the explanation of educational materials has proven to be effective. This approach is tailored to the specific nature of forensic activities, and it should be fully integrated into the process of training forensic engineering experts.