IMPROVEMENT OF THE METHOD OF CALCULATING THE STRESS-STATE AND STRENGTH OF REINFORCED CONCRETE STRUCTURES OF HYDRAULIC CORNER RETAINING WALLS WITH INTER-BLOCK JOINTS TAKING

2021 ◽  
pp. 62-69
Author(s):  
S. E. LISICHKIN ◽  
◽  
O.D. RUBIN ◽  
F. A. PASHCHENKO ◽  
N. S. KHARKOV
Keyword(s):  
Reinforced Concrete ◽  
Retaining Wall ◽  
Concrete Structures ◽  
Retaining Walls ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Structures ◽  
Wall Structures ◽  
Long Time ◽  
Characteristic Features ◽  
Inclined Cracks

Corner retaining walls are one of the most common structures of waterworks. Most of them were designed and built several decades ago and have been in operation for a long time. In some cases, there is a deviation from the design prerequisites and the strengthening of reinforced concrete structures of retaining walls is required. The main reason for these deviations is incomplete consideration of the characteristic features of retaining wall structures (including horizontal inter-block joints and secondary inclined cracks), as well as the nature of the loads acting on them. As a result, design horizontal transverse reinforcement is practically not installed in retaining walls that is not required by calculation based on traditional calculation methods.Traditional reinforcement schemes for retaining walls do not provide for the presence of horizontal inter-block joints and horizontal transverse reinforcement. As a result of the research carried out,the method for calculating the stress-strain state and strength of reinforced concrete structures of corner retaining walls with inter-block joints has been improved taking into account secondary stresses. Reinforcement schemes for retaining walls have also been improved.

STIFFNESS OF REINFORCED CONCRETE STRUCTURES UNDER BENDING WITH TRANSVERSE AND LONGITUDINAL FORCES

2021 ◽  
Vol 98 (6) ◽  
pp. 5-19
Author(s):  
VL.I. KOLCHUNOV ◽  
◽  
O.I. AL-HASHIMI ◽  
M.V. PROTCHENKO ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Concrete Structures ◽  
Bending Moment ◽  
Reinforced Concrete Structures ◽  
The Matrix ◽  
Local Shear ◽  
The Difference ◽  
Inclined Cracks ◽  
Opening Width

The authors developed a model for single reinforced concrete strips in block wedge and arches between inclined cracks and approximated rectangular cross-sections using small squares in matrix elements. From the analysis of the works of N.I. Karpenko and S.N. Karpenko the "nagel" forces in the longitudinal tensile reinforcement and crack slip , as a function of the opening width and concrete deformations in relation to the cosine of the angle . The experimental " nagel " forces and crack slip dependences for the connection between and in the form of an exponent for the reinforcement deformations and spacing are determined. The forces have been calculated for two to three cross-sections (single composite strips) of reinforced concrete structures. On the bases of accepted hypothesis, a new effect of reinforced concrete and a joint modulus in a strip of composite single local shear zone for the difference of mean relative linear and angular deformations of mutual displacements of concrete (or reinforcement) are developed. The hypothesis allows one to reduce the order of the system of differential equations of Rzhanitsyn and to obtain in each joint the total angular deformations of concrete and the "nagel" effect of reinforcement. The curvature of the composite bars has a relationship from the total bending moment of the bars to the sum of the rigidities. The stiffness physical characteristics of the matrix from the compressed concrete area and the working reinforcement are obtained in a system of equations of equilibrium and deformation, as well as physical equations.

scholarly journals The Mechanical Properties of Centrifuged Concrete in Reinforced Concrete Structures

2020 ◽  
Vol 10 (10) ◽  
pp. 3570
Author(s):  
Romualdas Kliukas ◽  
Ona Lukoševičienė ◽  
Arūnas Jaras ◽  
Bronius Jonaitis
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Concrete Strength ◽  
Concrete Structures ◽  
High Strength ◽  
Reinforcement Ratio ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Structures ◽  
Test Results ◽  
Moduli Of Elasticity

This article explores the influence of transverse reinforcement (spiral) and high-strength longitudinal reinforcements on the physical-mechanical properties of centrifuged annular cross-section elements of concrete. The test results of almost 200 reinforced, and over 100 control elements are summarizing in this article. The longitudinal reinforcement ratio of samples produced in the laboratory and factory varied from 1.0% to 6.0%; the transverse reinforcement ratio varied from 0.25% to 1.25%; the pitch of spirals varied from 100 mm to 40 mm and the concrete strength varied from 25 MPa to 60 MPa. Experimental relationships of coefficients for concrete strength, moduli of elasticity and limits of the longitudinal strain of centrifuged concrete in reinforced concrete structures in short-term concentrically compression were proposed.

scholarly journals Experimental studies of reinforced concrete structures of hydraulic structures strengthened with prestressed transverse reinforcement

2020 ◽  
Vol 16 (6) ◽  
pp. 504-512
Author(s):  
Oksana V. Zyuzina
Keyword(s):  
Reinforced Concrete ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Hydraulic Structures ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Structures ◽  
Joint Work ◽  
Transverse Cracks ◽  
Construction Joints ◽  
Concrete Model

Relevance. When repairing hydraulic structures, it is often necessary to face the task of strengthening them. Among the methods of strengthening retaining structures, the most interesting are those that allow to immediately include reinforcement elements in joint work with the structure and carry out work without removing the backfill soil from the rear edge. When choosing repair materials, attention should be paid to corrosion-resistant composite materials, the use of which in hydraulic engineering is not yet standardized, but the scope of their application is expanding every year. The main aim of experimental research is to strengthen the reinforced concrete structures of hydraulic structures, including those with interblock construction joints and transverse cracks, using prestressed transverse reinforcement. Methods. The investigations were carried out on a reinforced concrete model of a beam type reinforced with prestressed transverse reinforcement in the zone of inclined cracks formation. The model was made taking into account the typical tasks encountered during the repair of long-term operating retaining hydraulic structures with open seams and cracks, insufficient transverse reinforcement, low reinforcement coefficient, and initial deflection. Results. The task of strengthening a special reinforced concrete model using prestressed transverse reinforcement was realized. Experimental data were obtained on the nature of deformation and destruction, the opening of interblock construction joints and cracks, and the stresses in the reinforcement. Recommendations are given for strengthening the operated low-reinforced concrete structures of hydraulic structures with interblock construction joints with prestressed reinforcement.

scholarly journals Development of a method for calculating the stress state in horizontal sections of hydraulic engineering angular-type retaining walls

2019 ◽  
Vol 15 (5) ◽  
pp. 339-344
Author(s):  
Oleg D. Rubin ◽  
Sergey E. Lisichkin ◽  
Fedor A. Pashenko
Keyword(s):  
Reinforced Concrete ◽  
Stress State ◽  
Retaining Wall ◽  
Retaining Walls ◽  
Theory Of Elasticity ◽  
Hydraulic Engineering ◽  
Reinforced Concrete Structure ◽  
Characteristic Features ◽  
The 1960S ◽  
As Stress

Angular retaining walls are widespread in hydraulic engineering. They are characterized by large dimensions, small percentages of reinforcement, block cutting along the height of the structure. The bulk of the existing retaining walls were built in the 1960s-1980s. The regulatory documents that were in force during this period had certain shortcomings that caused the non-design behavior of a number of retaining walls. Improvement of calculation methods for reinforced concrete structures of retaining walls is required, within the framework of which a more complete account of the characteristic features of their behavior is needed. The aim of the work is to improve methods for calculating reinforced concrete retaining walls of a corner type. Methods of research carried out to improve the calculation of reinforced concrete retaining walls of the corner type included, among others, the classical methods of resistance of materials, the theory of elasticity, and structural mechanics. To determine the actual stress-strain state of the natural structures of retaining walls, visual and instrumental methods for examining retaining walls were used, including the method of unloading reinforcement. Results. To determine the stress state in the elements of the reinforced concrete structure of the retaining wall (in concrete and in reinforcement), a methodology was developed for calculating the stress state of retaining walls, which allows to determine the components of the stress state (stress in concrete in the compressed zone, as well as stress in stretched and compressed reinforcement) in horizontal sections of the vertical cantilever part of the retaining walls.

scholarly journals Foundations for shear wall structures

1980 ◽  
Vol 13 (2) ◽  
pp. 171-181
Author(s):  
J. R. Binney ◽  
T. Paulay
Keyword(s):  
Reinforced Concrete ◽  
Seismic Response ◽  
Concrete Structures ◽  
Shear Wall ◽  
Design Criteria ◽  
Reinforced Concrete Structures ◽  
Type Design ◽  
Wall Structures

After defining design criteria in general for foundations
of earthquake resisting reinforced concrete structures, principles 
are set out which govern the choice of suitable foundation systems
for various types of shear wall structures. The choice of
foundation systems depends on whether the seismic response of the superstructure during the largest expected earthquake is to be elastic or inelastic. For inelastically responding superstructures, preferably the foundation system should be designed to remain elastic. For elastically responding superstructures, suitable foundation systems may be energy dissipating, elastic or of the rocking type. Design criteria for each of these three foundation types are suggested.

scholarly journals The features of stress-deformation state of the lock chamber walls

Vestnik MGSU ◽  
2019 ◽  
pp. 473-483
Author(s):  
Oleg D. Rubin ◽  
Sergey E. Lisichkin ◽  
Valeriy B. Nikolaev ◽  
Dmitry S. Bashkirov
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Negative Consequences ◽  
Design Work ◽  
Normative Documents ◽  
Deformation State ◽  
Stress Deformation ◽  
Lock Chamber ◽  
Characteristic Features

Introduction. Reinforced concrete walls of lock installations are critical structures, since a decrease in their level of safety in the course of long-term operation can lead to negative consequences. Characteristic features of such structures determine their stress-deformation state and bearing capacity. So, an integral part of the lock chamber walls are inter-block construction joints (both horizontal and vertical), the presence of which is taken into account by regulatory and methodical documents existing in the recent decades. Materials and methods. There are used analytical methods for processing results of observing stress-deformation state of massive reinforced-concrete lock chamber walls as well as computational procedures and normative documents. Results. The analysis of the condition of a number of lock chamber walls of such domestic objects as Canal named in honour of Moscow, Kashkhatau hydroelectric power station, Pavlovsky lock, etc. has been conducted for this work. A special character of crack formation and stress-deformation state is noted, which required urgent measures for their strengthening and repair. The analysis of normative document provisions is performed for the documents existing at the time of design work on the most of these installations and ones in effect at the present time. Conclusions. The characteristic features are revealed for reinforced concrete structures of the lock chamber walls, which determine the features of their stress-deformation state. Due to the imperfection of the normative documents that were in effect during the designing the most of such structures, an off-design state arose in a number of cases that required urgent measures to strengthen and repair them. Improvement work is going on at the directions of methodology for calculating the stress-deformation state and strength of reinforced concrete structures in the lock chamber walls.

scholarly journals Experimental-theoretical studies of hydrotechnical angular-type retaining walls

2021 ◽  
Vol 17 (1) ◽  
pp. 82-91
Author(s):  
Fedor A. Pashchenko
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Retaining Walls ◽  
Variable Load ◽  
Reinforced Concrete Structures ◽  
Stress Strain ◽  
Term Operation ◽  
Stress Strain State

Relevance. Retaining walls are common structures that are part of waterworks. They have the characteristic features of hydraulic structures, such as large dimensions, low percentages of reinforcement (up to 1.0%), horizontal interblock joints. The listed features determine the nature of the work and the stress-strain state of the retaining walls. The main loads on the rear faces of the retaining walls are loads from the action of the backfill soil. The incomplete consideration of the design features and the nature of the loads action in the design of a number of retaining walls that are in the stage of long-term operation has caused the need to strengthen them. One of the reinforcement methods was to install reinforcement rods in drilled inclined holes in the zones of horizontal interblock joints. It was necessary to conduct experimental studies of reinforced concrete retaining walls under the action of various loads, in particular conside- ring the reinforcement by inclined rods. The aim of the experimental research was to study the effect of variable load on the stress-strain state of these structures, among others with due regard to inclined reinforcement installed in the zones of horizontal interblock joints. When solving the set tasks, proven experimental methods of researching reinforced concrete structures of hydrotechnical structures were used. Results. Experimental data from the study of models of retaining walls, including those with reinforcement by inclined reinforcement, at different locations of the resultant load on rear faces of models were obtained. An experimental substantiation of the reinforcement of reinforced concrete structures of retaining walls with an inclined reinforcement crossing horizontal construction joints has been carried out.

scholarly journals Stress-strain state of reinforced concrete structures of the LN-1 and LN-2 retaining walls of Zagorskaya PSPP taking into account the opening of interblock joints and the formation of secondary cracks

2021 ◽  
Vol 17 (4) ◽  
pp. 324-334
Author(s):  
Nartmir V. Khanov ◽  
Fedor A. Pashchenko
Keyword(s):  
Finite Element ◽  
Reinforced Concrete ◽  
Strain State ◽  
Retaining Walls ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Structures ◽  
Finite Element Models ◽  
Computational Studies ◽  
Stress Strain ◽  
Stress Strain State

Relevance. The lower retaining walls of the water intake of the Zagorskaya PSPP perform the important function of protecting the pressure water conduits from the collapse of the soil massif. Two of them (LN-2 and LN-3) were reinforced with anchor rods. Considering the long period of operation (more than 25 years), certain deviations in the work during examinations and field observations were revealed. So, on the front face of the walls, extended horizontal cracks were recorded (opening of horizontal interblock joints and the emergence of secondary oblique cracks on the front surface of the walls). To carry out computational studies of the stress-strain state of the downstream retaining walls was required. The purpose of the work was to determine the stress-strain state of the lower retaining walls of the water intake of the Zagorskaya PSPP taking into account the opening of interblock joints and the formation of secondary oblique cracks. Methods. Computational studies of the stress-strain state of retaining walls were carried out within the framework of the method of numerical modeling of reinforced concrete structures of hydraulic structures based on finite element models. In finite element models, structural features of retaining walls were reproduced, including anchor rods, horizontal interblock joints, actual reinforcement, secondary oblique cracks. Results. The stress-strain state of the retaining walls was obtained. The stresses in the longitudinal and transverse reinforcement were determined, including when the structure was changed due to anchor rods. In horizontally transverse reinforcement, tensile stresses exceeding the yield point are recorded. It took the development of measures to strengthen the lower retaining walls.

Damage to concrete structures due to the January 17, 1995, Hyogo-ken Nanbu (Kobe) earthquake

1996 ◽  
Vol 23 (3) ◽  
pp. 757-770 ◽  
Author(s):  
Denis Mitchell ◽  
Ronald H. DeVall ◽  
Katsumi Kobayashi ◽  
René Tinawi ◽  
W. K. Tso
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Transverse Reinforcement ◽  
Reinforced Concrete Structures ◽  
Concrete Construction ◽  
Kobe Earthquake ◽  
Short Columns ◽  
Insufficient Amount ◽  
Abrupt Changes ◽  
History Of

A brief history of the detailing changes following different Japanese earthquakes is presented. The design steps for reinforced concrete structures, as prescribed in the 1981 Japanese building code, are described. Observations on the damage and the collapse of reinforced concrete structures caused by the 1995 Hyogo-ken Nanbu earthquake are reported. Failures occurred in older structures built before the improved 1981 code. Deficiencies observed include discontinuities due to the change between composite steel and reinforced concrete construction and reinforced concrete construction in columns, poor detailing of transverse reinforcement in columns, lack of transverse reinforcement in beam–column joints, insufficient amount of vertical and horizontal reinforcement in walls, presence of significant torsional eccentricities, abrupt changes in stiffness over the height of buildings, and the use of "short" columns or "short" beams exhibiting high shear-to-moment ratios. The excellent performance of structures designed using the 1981 Japanese code is described. Key words: earthquake, Kobe, concrete structures, codes, damage, design.

scholarly journals Forced electric heating use for guaranteed quality of concrete clutching, restoring reinforced concrete structures

2021 ◽  
Vol 2131 (5) ◽  
pp. 052066
Author(s):  
V Molodin ◽  
S Leonovich ◽  
S Shpanko
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
Electric Heating ◽  
Cohesive Strength ◽  
Temperature Gradients ◽  
Cement Stone ◽  
Reinforced Concrete Structures ◽  
Guaranteed Quality ◽  
Long Time

Abstract Concrete adhesion is a decisive factor in restoring performance of reinforced concrete structures. Peeling of the repair concrete is observed, during the structures restoring that have been in operation for a long time in aggressive conditions. The studies of the carbon dioxide effect on cement stone showed crystalline framework destruction of the material and a decrease in its cohesive strength. This has a significant effect on grip. The use of forced heating of the repair mixture when it is placed in contact with the restored structure leads to the temperature gradients that enhance thermal diffusion and thus the impregnation of the damaged cement stone with the liquid phase from the repair concrete mixture. Crystallizing, the cement dissolution products form a new crystalline structure in the damaged cement stone, which enhances its cohesive strength and binds the repair concrete to the intact concrete structure of the restored structure, ensuring adhesion quality.

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