Nikolay Senkin, Tatyana Belyakova, Dmitry Malchikov, Valery Vasilyev
The Actual Operation of Steel Structures of Overhead Power Lines with a Voltage of 35 kV and Above
St. Petersburg State University of Architecture and Civil Engineering
Abstract. Modern computer technology and software allow the design of industrial and power grid facilities, taking into account additional clarifying factors. Therefore, research work on the study of the actual operation of steel structures of industrial buildings and electrical grid structures becomes relevant. The analysis of the results of full-scale tests of overhead power transmission lines structures is carried out, through which unknown facts are revealed that indicate the actual operation of power grid structures. Factors such as the displacement of foundations, the presence of significant deviations of the overhead line supports from the vertical and the uneven settlement of the foundations, the refinement of the design schemes of the above-foundation structures of the supports with different forms of connection of braces with chords, with rigid, hinged and elastic attachment of the chords to the foundations will ensure the development of more reliable and economical structural and technological solutions for steel poles of overhead power lines.
Keywords: overhead power line, support, tower, calculation model, actual work, joint work of structures and foundations.
Vadim Gubanov, Sergey Mishura, Elena Olenich
Reinforcement of the Plate Assembly of Steel Chimneys
Donbas National Academy of Civil Engineering and Architecture
Abstract. This article discusses the analysis of the impact of damage in the process of wear and reinforcement on the stress-strain state of the chimney lapel assembly. The defects and damages of the chimney are given on the basis of a survey of the technical condition of building structures. A computational model of the laminar assembly of the chimney with shells in the LIRA-SAPR 2021 PC has been developed, taking into account the identified defects and damages. A method has been developed for reinforcing the lapel assembly without a significant change in the structural forms and design schemes. The results of numerical studies of the stress-strain state of the lapel assembly at the design stage, after long-term operation and with strengthening of the chimney are presented. The influence of the thickness of the reinforcement elements on the change in stresses in the lap joint of the chimney is considered.
Keywords: stress state, steel chimney, guys, design scheme, lapel knot, reinforcement of structures.
Alexander Golikov a, Fedor Leychu b
Damageability and Actual Operation of Steel Structures of Beam-Type Coatings as Part of Building Frame Structures
a Institute of Architecture and Construction, Volgograd State Technical University,
b JSC «VNIKTIneftehimoborudovanie»
Abstract. Coverings of concert halls, assembly halls, meeting rooms and similar premises of civil buildings, as a rule, are made with spans of more than 15 m using steel as a material for supporting structures. The operation of coating structures is carried out in most cases with limited access for inspection and control of the technical condition, and in some objects, the bearing structures of the coating are not available for maintenance and control. Taking into account the cyclical nature of the development of modern society, characterized by periods of sharp declines and smooth rises, and relying on the experience established in the process of monitoring the technical condition of a number of buildings and structures, we note that in the life cycle of most structures there are periods of violations of normal operation and the absence of scheduled preventive repairs. During these periods, the destruction of the protective coatings of the surface of the structures, the violation of the tightness of the roofing, followed by the systematic soaking of the load-bearing structures and the accelerated process of degradation of the properties of materials over time, especially at the contact boundary of steel with concrete and brickwork. At the end of such periods, when the normal operation of structures is resumed, the actual models of the geometry of individual structures, the properties of materials of load-bearing structures, as well as the nature of the action of loads, differ from the models incorporated in the project. In the materials of this work, on the example of coatings of three buildings, a characteristic of the development of damages and some of the most characteristic parameters of the actual operation of steel structures of beam-type coatings as part of building frame structures are presented.
Keywords: load-bearing steel building structures, coating structures, defects, damage, work under load, stress-strain state, frame, loads and effects, bearing capacity, operation, repair and restoration measures, reinforcement.
Aleksandr Beglov a, Rudolf Sanzharovsky b, Tatyana Ter-Emmanuilyan c
Theory of Reinforced Concrete Calculation – Unique Experiments of Donetsk Scientists and Mistakes of World Theory
a Administration of St. Petersburg, b Eurasian National University L. N. Gumilyova, c Russian University of Transport
Abstract. This article analyzes the main provisions of the considered theory of concrete creep. Using the rules of mathematics, the principles of mechanics and the results of solid experiments, reveal: the fallacy of the superposition principle, which ultimately leads to the construction of incorrect kernels of integral equations; illegal substitution of instantaneous non-linear properties of concrete by creep properties (minute creep); non-stationary instantaneous elastic properties of concrete, turning into a model of Maxwell’s theory of creep, leading to an error of up to 300 %; only linear creep is considered, leading to an error of 200…500 %; the principle of «algebraization» of integral equations, naturally, leads to significantly contradictory results in the calculations of structures. It was revealed that the main provisions of the theory under consideration grossly violate the rules of mathematics, the principles of mechanics and the results of solid experiments.
Keywords: theory of concrete creep, overlay principle, instantaneous elastic deformations, long-term resistance of reinforced concrete, modern building codes, principles of the Eurocode.