Investigation of fatigue fracture processes for vibration reliability

International Scientific and Technical conference "The Progressive Technics, Technology and Engineering Education" ◽

10.20535/2409-7160.2021.xxii.238919 ◽

2021 ◽

Author(s):

Maksym Delembovskyi

Keyword(s):

Reinforced Concrete ◽

Fatigue Fracture ◽

Concrete Structures ◽

Reinforced Concrete Structures ◽

Main Task ◽

Construction Site ◽

High Quality ◽

Vibration Reliability ◽

Technical Solutions ◽

Fracture Processes

One of the important stages of obtaining reinforced concrete structures at a construction site, undoubtedly, is their manufacture. The process of creating reinforced concrete structures requires the use of appropriate technical solutions. One of these solutions is vibration pads, which perform the main task when creating high-quality reinforced concrete structures. The efficiency of the vibrating platforms is the key to ensuring the stable implementation of the complete technological process in the manufacture of reinforced concrete structures.

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STRENGTH OF LOW-REINFORCED CONCRETE STRUCTURES WITH THE INTERBLOCK CONSTRUCTION JOINTS REINFORCED BY PRESTRESSED BASALT-COMPOSITE BARS

Prirodoobustrojstvo ◽

10.26897/1997-6011-2021-1-53-62 ◽

2021 ◽

pp. 53-62

Author(s):

O. D. RUBIN ◽

◽

S. E. LISICHKIN ◽

O. V. ZYUZINA

Keyword(s):

Reinforced Concrete ◽

Experimental Studies ◽

Concrete Structures ◽

Hydraulic Structures ◽

Reinforced Concrete Structures ◽

External Reinforcement ◽

Block Construction ◽

Construction Joints ◽

Technical Solutions ◽

Composite Reinforcement

Many slightly reinforced concrete structures of operating hydraulic structures need strengthening. Traditional methods of strengthening (by reinforced concrete, metal structures, etc.) have significant disadvantages. A method of strengthening by external reinforcement systems based on carbon fiber which is effective in cases where there is an access to the tension zone of the reinforced structures begins to spread. The authors propose to strengthen slightly reinforced concrete structures of the operated hydraulic structures with pre-stressed basalt composite reinforcement placed in the pre-drilled holes in the concrete of the reinforced structures. To substantiate the proposed technical solutions there was carried out a set of experimental studies of characteristic slightly reinforced concrete structures of hydraulic facilities (including those with inter-block construction joints) reinforced with pre-stressed basalt composite reinforcement. The results of experimental studies have shown the effectiveness of strengthening low-reinforced concrete structures of operating hydraulic facilities with inter block construction joints by means of pre-stressed: longitudinal basalt composite reinforcement and transverse reinforcement.

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Design of precast reinforced concrete structures of frame buildings: a new set of rules

Promyshlennoe i Grazhdanskoe Stroitel stvo ◽

10.33622/0869-7019.2019.04.04-09 ◽

2019 ◽

pp. 4-9 ◽

Cited By ~ 1

Keyword(s):

Reinforced Concrete ◽

Concrete Structures ◽

Reinforced Concrete Structures ◽

Building Frames ◽

Fine Grained ◽

Rigid Frame ◽

Floor Slabs ◽

Frame Buildings ◽

Spatial System ◽

Precast Elements

Currently, prefabricated reinforced concrete structures are widely used for the construction of buildings of various functional purposes. In this regard, has been developed SP 356.1325800.2017 "Frame Reinforced Concrete Prefabricated Structures of Multi-Storey Buildings. Design Rules", which establishes requirements for the calculation and design of precast reinforced concrete structures of frame buildings of heavy, fine-grained and lightweight structural concrete for buildings with a height of not more than 75 m. The structure of the set of rules consists of eight sections and one annex. The document reviewed covers the design of multi-story framed beam structural systems, the elements of which are connected in a spatial system with rigid (partially compliant) or hinged joints and concreting of the joints between the surfaces of the abutting precast elements. The classification of structural schemes of building frames, which according to the method of accommodation of horizontal loads are divided into bracing, rigid frame bracing and framework, is presented. The list of structural elements, such as foundations, columns, crossbars, ribbed and hollow floor slabs and coatings, stiffness elements and external enclosing structures is given; detailed instructions for their design are provided. The scope of the developed set of rules includes all natural and climatic zones of the Russian Federation, except seismic areas with 7 or more points, as well as permafrost zones.

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Improvement Of Curvilinear Diagrams Of Concrete Deformation

Promyshlennoe i Grazhdanskoe Stroitel stvo ◽

10.33622/0869-7019.2019.08.99-104 ◽

2019 ◽

pp. 99-104

Keyword(s):

Reinforced Concrete ◽

Peak Load ◽

Experimental Studies ◽

Concrete Structures ◽

Deformation Model ◽

Reinforced Concrete Structures ◽

Significant Difference ◽

Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

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