scholarly journals Impact of rockfill dam structure heterogeneity on reinforced concrete face stress-strain state

2019 ◽  
pp. 5-5 ◽  
Author(s):  
Mikhail Sainov ◽  
Igor Egorov ◽  
Konstantin Pak
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Longitudinal Force ◽  
Heterogeneous Structure ◽  
Stress Strain ◽  
Stress Strain State ◽  
Rockfill Dam ◽  
Deformation Properties ◽  
The Face ◽  
Concrete Face

Introduction. One of the main principles in designing modern ultra-high rockfill dams with reinforced concrete face is the principle of zoning rockfill of various quality in the dam body. It envisages that rockfill in the shell upper part should be compacted very carefully in order to minimize to the maximum the deflections of the reinforced concrete face. In the shell lower part it is allowed placing heterogeneous rockfill with less degree of compaction. Analysis of the results of field observations over settlements of the already constructed dams shows that this pattern of zoning may lead to considerable irregularity in distribution of rockfill deformation moduli between the upstream and the downstream parts of the dam. Numerical modeling of the existing Aguamilpa dam carried out by use arlier showed that this effect may be caused by unfavorable stress-strain state of the reinforced concrete face threatening with crack formation. Were come ended using dams of homogenous structure. However, this conclusion caused doubts of some experts. More detailed studies who see results are described in this article were conducted in order to confirm or disprove this conclusion. Materials and methods. The studies were conducted by finite element method on the example of 100 m high rockfill dam. Different alternatives of rockfill deformation properties in the shell upstream and downstream parts were considered. Results. Analysis of the results of studies confirmed the conclusions made earlier about the features of the rockfill dam reinforced concrete face stress-strain state. It was revealed that increase of rockfill deformation in the dam shell downstream part leads to appearance of additional tensile longitudinal force in the face. It increases the risk of appearance of through transversal cracks in the face. However, the heterogeneous structure of the dam shell may not have a decisive impact on stress values because the value of bending moment plays a great role. Conclusions. The results of the fulfilled study as well as modern dam construction practice show the necessity of modifying the traditional pattern of rockfill zoning in the dam body. It is necessary to provide decrease of differences in rockfill deformation of the upstream and downstream parts of the dam.

scholarly journals IMPACT OF DAM ROCKFILL CREEP ON REINFORCED CONCRETE FACE STRESS-STRAIN STATE

2019 ◽  
Author(s):  
Mikhail P. Sainov ◽  
Andrey Yu. Kirichenko
Keyword(s):  
Reinforced Concrete ◽  
Rheological Model ◽  
Strain State ◽  
Time Dependent ◽  
Favorable Effect ◽  
Stress Strain ◽  
Stress Strain State ◽  
Operation Period ◽  
The Face ◽  
Concrete Face

Introduction. Rockfill deformations are developed during long time. It is known that most intensive they are during construction period, but their increment continues also during operation period due to creep. Therefore, creep may affect the reinforced concrete face stress-strain state. Nevertheless, search for the scientific and technical information showed that the problem of creep impact on the face strength is poorly studied. Materials and methods. Studies of stress-strain state were conducted with the aid of numerical modeling by finite element method. They were carried out on the example of in-situ Toulnustouc dam, which deformations during the operation period are known by the results of field measurements. For simulation of the time-dependent dam, deformation increment process there was chosen a rheological model of soil and a technique was worked out for calculating the dam stress-strain state. At plotting the rheological model, the use was made of the simplest exponential relationship of time-dependent deformations. Results. The parameters of the rockfill model were determined by selection from condition of matching between the dam design displacements and the field data. For the considered dam, the rockfill creep has not resulted in cardinal changes in the reinforced concrete face stress-strain state. Conclusion. It was revealed that increase of the dam settlements due to creep has a favorable effect: they create additional compressive longitudinal force in the face.

scholarly journals Role of transverse joints in regulation of the reinforced concrete face stress-strain state

Vestnik MGSU ◽  
2018 ◽  
pp. 1533-1545
Author(s):  
Aleksei A. Podvysotckii ◽  
Mikhail P. Sainov ◽  
Vladislav B. Soroka ◽  
Roman V. Lukichev
Keyword(s):  
Numerical Modeling ◽  
Reinforced Concrete ◽  
Strain State ◽  
Tensile Force ◽  
Bending Moments ◽  
Stress Strain ◽  
Tensile Stresses ◽  
Stress Strain State ◽  
Transverse Joint ◽  
The Face

Introduction. Deals with the results of studying effectiveness of arranging transverse joints in the face as the means of regulation of its stress-strain state. At present reinforced concrete faces are constructed without being cut height-wise and transverse joints may be arranged only at the end of the dam construction stages. This is validated by the fact that experience in construction of flexible (discontinuous) faces has not demonstrated the required level of safety of this structural design. However, in the dams of the up-to-date structural designs, maintaining the face integrity is not guaranteed: cracks appeared in reinforced concrete faces at a number of high dams. Formation of cracks in faces should be attributed to presence of tensile stresses, whose values exceed concrete tensile strength. To prevent seal failure of the seepage-control element it is feasible to provide arrangement of the transverse joint in the face section where tensile stresses may be expected. Materials and methods. The studies were conducted on the example of a 100 m high dam with the aid of numerical modeling. Rockfill was considered as a lineally deformed material, but computations were conducted for a wide range of the soil linear deformation modulus: from 60 to 480 МPа. Steel reinforcement was considered in the face. Transverse joints were modelled with the aid of contact finite elements. Results. By the results of numerical modeling the tensile stresses appear in the uncut face due to bending deformations and deformations of longitudinal extension. The most hazardous is the face lower section. At this section the longitudinal tensile force and considerable moment are acting. Transverse joints are feasible to be arranged in this particular section of the face. Conclusion. It was revealed that the main positive effect of the transverse joint arrangement is in decreasing the value of longitudinal tensile force perceived by the face. Impact of the transverse joint on bending moments has a local effect and covers the section of the limited length. Moreover, at arranging joints the values of bending moments may increase. We may recommend arrangement of a transverse joint in the face which is parallel to the perimeter joints only in the face lower part which is subject to longitudinal deformation.

scholarly journals Concrete-faced rockfill dams: experience in study of stress-strain state

Vestnik MGSU ◽  
2019 ◽  
pp. 207-224 ◽  
Author(s):  
Vladislav B. Soroka ◽  
Mikhail P. Sainov ◽  
Denis V. Korolev
Keyword(s):  
Numerical Modeling ◽  
Reinforced Concrete ◽  
Strain State ◽  
Stress Strain ◽  
Linear Character ◽  
Stress Strain State ◽  
Operation Conditions ◽  
Numerical Studies ◽  
Deformation Properties ◽  
The Impact

Introduction. At present the urgent problem in hydraulic construction is establishing the causes of crack formation in seepage-control reinforced concrete faces at a number of rockfill dams. For solving this problem the studies are conducted of stress-strain state (SSS) of concrete-faced rockfill dams which are fulfilled by different methods. Materials and methods. Gives a review and analysis of the results of studies of stress-strain state of concrete-faced rockfill dams (CFRD) fulfilled by different authors over the last 15 years. The results of analytical, experimental and numerical studies are considered. Descriptions are given of the models used for simulation of non-linear character of rockfill deformation at numerical modeling of dam SSS. Results. Analysis showed that solving the problem of CFRD SSS causes a number of methodological difficulties. At present the only method permitting study of CFRD SSS is numerical modeling. The rest methods do not permit considering the impact of important factors on SSS. Large complications are caused by scarce knowledge of rockfill deformation properties in real dams. Conclusions. It was revealed that at present SSS of reinforced concrete faces has been studied insufficiently. The results of conducted studies do not give full and adequate understanding about operation conditions of reinforced concrete faces. Impact of various factors on the face SSS has not been studied. Besides, there are contradictions in the results of studies obtained by different authors. Differences in the results are based on objective and subjective reasons. A considerable obstruction for numerical studies is complicated modeling of rigid thin-walled reinforced concrete face behavior at large deformations inherent to rockfill. The obtained results of studies often do not permit conducting full analysis of SSS of concrete-faced rockfill dams.

Investigation of the Stress-Strain State of a Steel Column Base Connection for Seismic Regions

2022 ◽  
Vol 906 ◽  
pp. 93-98
Author(s):  
Tigran Dadayan ◽  
Lusine Karapetyan
Keyword(s):  
Reinforced Concrete ◽  
Strain State ◽  
Main Type ◽  
Industrial Building ◽  
Stress Strain ◽  
Concrete Foundation ◽  
Stress Strain State ◽  
Steel Base ◽  
Steel Column ◽  
Seismic Regions

Currently, the main type of connection between a steel column and a reinforced concrete foundation is a steel base, which is often economically unprofitable due to its size, number or diameter of anchor bolts. Not only in Armenia, but also in most countries, a steel base is the main type of connection between a steel column and a reinforced concrete foundation. The usage of other types of connections is associated with both new calculation methods and technological problems. The possibility of computation and design of the connection of a steel column with a reinforced concrete foundation in seismically active regions using shear studs is considered in this work, a reinforced concrete section with longitudinal reinforcement is used for this type of connection which ensures a smooth transfer of forces from the column to the foundation. Based on the example of the connection of a single-story industrial building column shows the change in the stress-strain state of the connection under axial force and bending moments for seismic regions. Not only the feature and construction technology of the connection considered in the work, but also proposes a calculation method with future possibility of its subsequent inclusion in the building codes of the Republic of Armenia.

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