Viktor Levin a, Leonid Steblyanko b
Numerical Analysis of the Stress-Strain State of the Prestressed Prefabricated Reinforced Concrete I-beam as Subject of Mechanics of Deformed Solid Body
a Donbas National Academy of Civil Engineering and Architecture, b SSL «Evrograd»
Abstract. The article presents the results of analysis of the stress-strain state of prestressed precast reinforced concrete I-beam, the mathematical modeling of which was carried out by means of mechanics of a deformable solid. The long-term deformations preceding loading due to prestressing, elastic-plastic deformation, and the formation of cracks under the main loading are taken into account. Models of material deformation are accepted: before cracking – deformation theory of plasticity of flat-stressed concrete by Kruglov-Kozachevsky (it takes into account the elastic-plastic nature of volumetric and shear deformation) and full deformation diagrams of reinforcement; after crack formation – Karpenko’s model for reinforced concrete (it takes into account such effects as uneven distribution of deformations along the axis of the reinforcing bar crossing the crack, the peculiarities of deformation of the concrete strip between cracks, the pin effect in the reinforcement, the symmetry of the force tensor in reinforced concrete with asymmetric stress tensors in reinforcement and concrete separately, etc.). The method of incomplete discretization is applied in the form of the method of the original Mileikovsky equations; it leads to a boundary value problem for a system of ordinary differential equations of the first order, solved by the highly efficient Godunov method.
Keywords: reinforced concrete I-beam, concrete, reinforcement, stresses, deformations, cracks, creep, elastoplastic deformations, uneven distribution of deformations, loading, and deflection.
Sergii Mashtaler
Analysis of the Stress-Strain State of the Foundation for the Cooling Device of Steelmaking Production with the Option of Using High-Strength Steel Fiber Concrete
Donbas National Academy of Civil Engineering and Architecture
Abstract. The results of the analysis of the technical state of the columnar foundation of the refrigeration unit of the continuous casting machine (CCM) of the SP «Metalen», as well as theoretical studies of the effectiveness of the use of high-strength steel-fiber-reinforced concrete for the the construction of the foundations of CCM, using software package «Lira-SAPR 2017», are presented in this article. An example of using the diagrammatic method in calculating the foundation, taking into account the actual operating mode of the structure under conditions of exposure to high temperatures, is considered. Numerical results of the influence of the nonuniformity of temperature and shrinkage deformations on the parameters of the stress-strain state of the structure are obtained. Numerical studies have established, that the use of high-strength steel-fiber reinforced concrete of class B100 with μsfb = 2,5 % instead of concrete of class B40 under the combined effect of force and high temperature and shrinkage actions, taking into account the physical nonlinearity of materials, leads to a decrease in compressive and tensile stresses by up to 25 %, while the maximum crack width is lesser than 0,1 mm, which does not exceed maximum permissible values.
Keywords: columnar foundations, stress-strain state, temperature and humidity effects, high-strength steel fiber concrete.
Vitaly Datsenko a, Andrey Gerbutov b, Viktoriya Zubova a
Expanding the Functionality of Side-loading Garbage Trucks by Using a Grappling Hook
a Donbas National Academy of Civil Engineering and Architecture, b Snezhnyansky Mining Technical school
Abstract. The paper considers the issue of improving the efficiency of technology and means of mechanization of collection and transportation of solid household waste from places of their unauthorized accumulation. The analysis of modern methods of waste management was made, during which it was established that the costs of waste transportation prevail over other costs during their further processing or disposal. Research, held in the city Snezhnoe showed that more than 40 % of unauthorized waste generation sites are located near public roads, while the distance from the roadway is usually no more than 5 meters. Based on the analysis of the design features of side-loading garbage trucks and their load-grabbing devices, a technology for eliminating unauthorized landfills using side-loading garbage trucks equipped with a quick-release grab is proposed. The design justification of the possibility of using the proposed removable equipment was made by creating a 3D model of the grab and its strength analysis in the APM FEM environment.
Keywords: solid household waste, transportation, grabs, garbage truck, container, and manipulator.
Yurii Novichkov, Artem Kravchenko
Justification of Hardware for the Technological Process of Processing liquid Pyrolysis Products of Automotive Tires
Donbas National Academy of Civil Engineering and Architecture
Abstract. The paper considers the issue of improving the efficiency of the technological line for processing liquid pyrolysis products of motor-vehicle and tractor tires in order too btain high-quality secondary products in the form of furnace fuel. The analysis of the composition of the technological equipment necessary for the operation of a promising technological line is carried out. In accordance with the requirements of compliance with the technology of processing motor-vehicle and tractortires, as well as to ensure the reliability and mechanization of production, the technical parameters of the mixing apparatus are determined. A module for calculating the material balance indicators of the production line has been developed, and the dependences of the volume of liquid product requirements on the performance and type of pyrolysis reactor have been obtained. It is established that in order to create industrial and environmental safety during the operation of the technological complex, the proposed technological scheme must be supplemented with an intermediate storage tank for raw-resin.
Keywords: automotive tires, processing, pyrolysis, furnace fuel, mixer, mixing apparatus, calculation module.
Dmitriy Belitskiy, Nikita Nosach, Gleb Matko
Stand for Studying the Processes of Destruction of Reinforced Concrete Pillars and Preparation for Disposal
Donbas National Academy of Civil Engineering and Architecture
Abstract. The article discusses the relevance of recycling and recycling of reinforced concrete structures. A number of domestic and foreign publications on this topic are considered. The existing technologies of recycling of reinforced concrete structures are determined. It is indicated that the degradation processes occurring in reinforced concrete structures associated with corrosion of reinforcement reduce its adhesion to concrete by 60…70 %. The technology of destruction of long-length reinforced concrete structures (poles, supports of power lines) by bending with subsequent cleaning of the reinforcement from the stuck concrete by vibration-shock action is proposed. It has been developed the equipment that allows you to prepare and dispose of reinforced concrete products. The article presents a design diagram and a photo of a manufactured stand for destroying reinforced concrete pillars and preparing them for disposal. The tests have proved the effectiveness of the developed equipment.
Keywords: recycling, technology, stand, reinforced concrete product, bending moment, vibration, recycling.