MOMENTS IN REINFORCED CONCRETE STRUCTURES UNDER BENDING WITH TORSION

2021 ◽  
Vol 95 (3) ◽  
pp. 27-46
Author(s):  
VL.I. KOLCHUNOV ◽  
◽  
A.I. DEMYANOV ◽  
M.V. PROTCHENKO ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Computational Model ◽  
Cross Sections ◽  
Neutral Axis ◽  
Reinforced Concrete Structures ◽  
The Third ◽  
Straight Line ◽  
The Family ◽  
Third Stage ◽  
Concrete Blocks

The moments in reinforced concrete during bending with torsion were determined, the new first hypothesis of linear deformations and its filling of the diagram during bending with torsion for the analytical second functional as a function of three functions - an exponent, a straight line and a parabola curve. A simple new method is found (from the family of mesh methods) and a summed function of additional deplanation is proposed. The new second hypothesis of angular deformations and its filling of the diagram in reinforced concrete during bending with torsion is constructed. The analytical first general undefined functional is a function of functions, as well as transitions, operations between functions. At the same time, a spatial triple integral of arguments from longitudinal deformations for the first hypothesis was obtained, as well as the third and fourth functionals (indefinite and definite) from moments (bending and twisting) with the projection of the coefficients of the diagram of "deformations - stresses" of compressed concrete and the filling coefficients of the diagrams of compressed concrete for their shoulders to the neutral axis for a field of small squares. The bending and torque moments from the compressed area of concrete and working reinforcement are determined (folded for their levels or expanded into algebraic functions from the synthesis of the computational model of reinforced concrete blocks). In this case, we have new functionals (from the first to the fourth functional), proposed hypotheses (first and second), as well as cross sections (from small squares) to a spatial crack. There are also jumps (cracks) lateral, normal, etc., from the first - third stage of average deformations of concrete and working reinforcement.

scholarly journals Natural infection of Deroceras laeve (Mollusca: gastropoda) with metastrongylid larvae in a transmission focus of abdominal angiostrongyliasis

2002 ◽  
Vol 44 (1) ◽  
pp. 53-54 ◽  
Author(s):  
Rafael Lucyk MAURER ◽  
Carlos GRAEFF-TEIXEIRA ◽  
José Willibaldo THOMÉ ◽  
Luís Antônio CHIARADIA ◽  
Hiroko SUGAYA ◽  
...  
Keyword(s):  
Epidemiological Study ◽  
Natural Infection ◽  
Southern Brazil ◽  
Intermediate Hosts ◽  
Santa Catarina ◽  
Crop Pest ◽  
The Third ◽  
The Family ◽  
Third Stage ◽  
First Time

Angiostrongylus costaricensis is a nematode parasitic of rodents. Man may become infected by ingestion of the third stage larvae produced within the intermediate hosts, usually slugs from the family Veronicellidae. An epidemiological study carried out in a locality in southern Brazil (western Santa Catarina State) where these slugs are a crop pest and an important vector for A. costaricensis has documented for the first time the natural infection of Deroceras laeve with metastrongylid larvae. This small limacid slug is frequently found amid the folds of vegetable leaves and may be inadvertently ingested. Therefore D. laeve may have an important role in transmission of A. costaricensis to man.

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.

The Family Group in Golden Hamsters: Its Formation and Break-Up

Behaviour ◽  
1961 ◽  
Vol 17 (2-3) ◽  
pp. 81-94 ◽  
Author(s):  
T.E. Rowell
Keyword(s):  
Small Groups ◽  
Experimental Tests ◽  
Natural Conditions ◽  
Play Fighting ◽  
The Third ◽  
Contact Behaviour ◽  
The Family ◽  
Third Stage ◽  
Three Stages ◽  
Break Up

AbstractI. Behaviour of the golden hamster during normal parturition is described. 2. This is compared with behaviour of mothers who did not rear their litters because of faulty response to suckling attempts by the pups. Absence of milk at the nipples is suggested as a cause for this unwillingness to nurse. 3. Pups which are not born in the nest are often abandoned. 4. Pups born dead are often treated as food, but live pups are not eaten until after parturition is over. 5. Litters do not form into the characteristic compact unit until they have fed and been brooded. 6. Three stages in family break-up are recognised: (i) At about twentyfive days the mother begins to wean her litter, stops rebuilding the old nest, and may build a smaller one elsewhere. It is possible she would normally leave her litter at this point. (ii) During their fifth week the pups stop trying to suckle and showing contact behaviour ; they begin to sleep in small groups, and seem to try to escape from the mother's cage. At this time the mother attacks them occasionally. (iii) With sexual maturity of the females (six weeks) play-fighting stops, and marking was not seen. If a female becomes pregnant she becomes dominant in a few days, but does not dare fight the mother. 7. It is likely that the third stage is an artefact of captivity and that the litter would be left by the mother in stage (i) and would largely disperse during stage (ii) in natural conditions. 8. The interpretations of observations described are necessarily tentative, and need experimental tests before they can be accepted.

The Construction of the Diagrammatic Deformation Model for Calculating the Core Reinforced-Concrete Structures in Finite Increments under Joint Action of Load Increments and Variable by Cross Sections Low and Ultra Low Subzero Temperatures

2021 ◽  
Vol 887 ◽  
pp. 665-671
Author(s):  
N.I. Karpenko ◽  
S.N. Karpenko ◽  
D.Z. Kadiev ◽  
G.A. Moiseenko
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Computer Calculation ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
The Core ◽  
Use Of Time ◽  
Subzero Temperatures ◽  
Iteration Methods

The use of the nonlinear deformation model in computer calculation methods involves the use of time-consuming step-iteration methods for solving systems of resolving equations with problems of convergence. To eliminate these difficulties, the physical relations of the deformation model are established in finite increments. The article considers the construction of such a model in finite increments as applied to the calculation of the core reinforced-concrete structures in the overall case of oblique bending and oblique eccentric compression or tension, taking into account the action by the cross sections of low subzero temperatures.

A solution to the thermal problem of fire resistance of spun reinforced concrete columns

2021 ◽  
Vol 30 (2) ◽  
pp. 49-70
Author(s):  
I. I. Palevoda ◽  
D. S. Nekhan
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Cross Sections ◽  
Fire Resistance ◽  
Concrete Structures ◽  
Concrete Columns ◽  
Full Scale ◽  
Reinforced Concrete Structures ◽  
Thermal Problem ◽  
Reinforced Concrete Columns

Introduction. Spun reinforced concrete columns are widely used in the present-day international construction practice. Known formulas, used to calculate temperatures of cross sections of reinforced concrete structures, needed to assess their fire resistance limit, are successfully applied to homogeneous structures that have solid sections. However, they are inapplicable to spun reinforced concrete columns due to their structural features. The purpose of this work is to develop a method for solving a thermal problem of spun reinforced concrete columns and adapt existing calculation formulas.Materials and methods. This work addresses the heating of spun reinforced concrete structures in case of fire. Ansys Workbench was employed to perform the computer simulation needed to study the influence of the characteristics of spun reinforced concrete columns on their heating. Results and discussion. In the course of the theoretical studies, the effect, produced by column cavities, the heterogeneity of spun concrete and thin walls of these structures on the heating of their cross sections was assessed with regard for the results of full-scale fire tests of spun reinforced concrete columns. Correction coefficients were obtained in order to take account of these factors. A regression equation was derived as a result of the simulation performed in the context of a full-scale factorial experiment involving coefficient khol, which takes into account the rising temperature of hollow reinforced concrete structures in comparison with solid ones. Khet heating acceleration coefficient is applicable to spun reinforced concrete structures due to the heterogeneity of concrete in the cross section. This coefficient represents a function of the wall thickness. Coefficient kth, which allows for the heating acceleration in the course of crack opening in thin-walled structures, varies in the range of 1.00…1.40. The concrete cracking temperature is 550 °C.Conclusion. A new method allows to solve the thermal problem of fire resistance of spun reinforced concrete columns. The engineering formula used to calculate the temperature in a cross-section was adapted. The results of computer-aided simulation and calculation of temperature values, performed using the adapted formula, show acceptable convergence with the experimental data.

Calculation Models of the Bearing Capacity of Span Reinforced Concrete Structure Support Zones

2019 ◽  
Vol 968 ◽  
pp. 209-226
Author(s):  
Vasyl M. Karpiuk ◽  
Yulia A. Syomina ◽  
Diana V. Antonova
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Cross Sections ◽  
Concrete Structure ◽  
Strain State ◽  
Complex Stress ◽  
Deformation Analysis ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Structure

Experience gained in design, erection and operation of span reinforced concrete structures has proved that practically all of them are subject to complex stress-strain state. At that, the researchers pay considerable greater attention to calculation of strength, deformation analysis and determination of crack resistance in normal cross-sections than to calculation of their support zones, including oblique sections, which results are generally taken into account for determining the section dimensions and the quantity of the cross reinforcement.

Computational model of textile-reinforced concrete structures

2004 ◽  
Vol 82 (23-26) ◽  
pp. 1971-1979 ◽  
Author(s):  
S. Holler ◽  
C. Butenweg ◽  
S.-Y. Noh ◽  
K. Meskouris
Keyword(s):  
Reinforced Concrete ◽  
Computational Model ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Textile Reinforced Concrete

scholarly journals CALCULATION SCHEME OF REINFORCED CONCRETE STRUCTURES OF CIRCULAR CROSS-SECTION UNDER BENDING WITH TORSION

2021 ◽  
Vol 17 (3) ◽  
pp. 63-82
Author(s):  
Vladimir Kolchunov ◽  
Sergey Bulkin
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Concrete Structures ◽  
Circular Cross Section ◽  
Shear Stresses ◽  
Reinforced Concrete Structures ◽  
Dowel Action ◽  
The Moment ◽  
External Forces ◽  
Spatial Section

The developed design diagram of the ultimate resistance of reinforced concrete structures in bending with torsion of circular cross-sections most fully reflects the features of their actual exploitation. For a spatial crack of a diagonal large ellipse, sections are taken in the form of a swirling propeller with concave and convex spatial parabolas from the first and second blocks between vertical transverse circular sections from the beginning to the end of the crack. For practical calculations in compressed and tensioned concrete, a polyline section of three sections is considered: two longitudinal trapezoids and the third middle section of the radius curve of a small ellipse close to forty-five degrees. When calculating unknown forces, solutions of the equations of equilibrium and deformations of the sections are made up to the end of the crack passing through the moment points for the resultant moments and the projections of internal and external forces. Shear torsional stresses along the linear longitudinal sections of the trapezoid were presented, as well as normal and shear stresses located on the end cross-sections at a distance x from the support. The height of the compressed area of concrete decreases with an increase in bending moments in the spatial section between the first and third cross-sections. It is found in their relationships and connections. The dowel action of reinforcement is determined using a special model of the second level with discrete constants. The static loading scheme was considered from the standpoint of an additional proportional relationship between the torques along the length of the bar in the spatial section and the first and third transverse sections. For a dangerous spatial crack, when projected onto the horizontal axis, the length C was found from a diagonal large ellipse of a round bar.

scholarly journals On direct determination of shear force taken up by concrete in oblique cross-sections of reinforced concrete structures

2021 ◽  
Vol 34 (02) ◽  
pp. 1039-1048
Author(s):  
Aleksei N. Morozov
Keyword(s):  
Reinforced Concrete ◽  
Cross Sections ◽  
Shear Force ◽  
Concrete Structures ◽  
Direct Determination ◽  
Computation Method ◽  
Reinforced Concrete Structures ◽  
Normal Section ◽  
Stress Block

A method has been presented for the direct determination of shear force in oblique cross-sections of reinforced concrete structures using a classic formula Q=bzτ, when the main problems of determining the shear force in oblique cross-sections are related to finding cleaving stresses in concrete and the shape of a stress-block of normal stresses in the design section, with no principles of practical division between the forms of failure in oblique sections due to concrete compression or shear. This work incorporates a criterion for dividing the forms of failure due to concrete compression or shear, based on the assumed shape of a compression stress-block with a segment cut away in a normal section, passing through the top of an inclined crack. The height of the compressed area in this normal section is defined from simultaneous solution of the equations of equilibrium in the moments in normal and oblique sections, from testing the experimental beams made of concrete and gas-concrete. This work deals with seeking the approaches for solving the above-mentioned problems in practice. The data of testing beams from gas-concrete and heavy-weight concrete have been used. Strain gauges were used to measure concrete and reinforcement deformities, computer processed thereafter. The studies have been considered on determination of cleaving stresses in oblique sections, further verified according to this method on certain alternative schemes of their application. A practical method for finding the shear force depending on the value of a shear span has been proposed. The work can encourage active discussion of this computation method.

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