Multicriterion optimization of quality indicators of the cross section of a reinforced-concrete element

1993 ◽  
Vol 28 (6) ◽  
pp. 568-572
Author(s):  
A. F. Kregers ◽  
G. A. Teters ◽  
Yu. G. Melbardis
Keyword(s):  
Reinforced Concrete ◽  
Quality Indicators ◽  
Cross Section ◽  
Concrete Element ◽  
Multicriterion Optimization ◽  
The Cross

SETTING A DIAGRAM APPROACH TO CALCULATING VIBRATED, CENTRIFUGED AND VIBROCENTRIFUGED REINFORCED CONCRETE COLUMNS WITH A VARIATROPIC STRUCTURE

2020 ◽  
pp. 22-34
Author(s):  
Л. Р. Маилян ◽  
С. А. Стельмах ◽  
Е. М. Щербань ◽  
М. П. Нажуев
Keyword(s):  
Experimental Data ◽  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Cross Section ◽  
Concrete Columns ◽  
Reinforced Concrete Columns ◽  
The Cross ◽  
Concrete Elements ◽  
Diagram Approach

Состояние проблемы. Железобетонные элементы изготавливаются, как правило, по трем основным технологиям - вибрированием, центрифугированием и виброцентрифугированием. Однако все основные расчетные зависимости для определения их несущей способности выведены, исходя из основного постулата - постоянства и равенства характеристик бетона по сечению, что реализуется лишь в вибрированных колоннах. Результаты. В рамках диаграммного подхода предложены итерационный, приближенный и упрощенный способы расчета несущей способности железобетонных вибрированных, центрифугированных и виброцентрифугированных колонн. Выводы. Расчет по диаграммному подходу показал существенно более подходящую сходимость с опытными данными, чем расчет по методике норм, а также дал лучшие результаты при использовании дифференциальных характеристик бетона, чем при использовании интегральных и, тем более, нормативных характеристик бетона. Statement of the problem. Reinforced concrete elements are typically manufactured according to three basic technologies - vibration, centrifugation and vibrocentrifugation. However, all the basic calculated dependencies for determining their bearing capacity were derived using the main postulate, i.e., the constancy and equality of the characteristics of concrete over the cross section, which is implemented only in vibrated columns. Results. Within the framework of the diagrammatic approach, iterative, approximate and simplified methods of calculating the bearing capacity of reinforced concrete vibrated, centrifuged and vibrocentrifuged columns are proposed. Conclusions. The calculation according to the diagrammatic approach showed a significantly better convergence with the experimental data than that using the method of norms, and also performs better when using differential characteristics of concrete than when employing integral and particularly standard characteristics of concrete.

Flexural capacity and design of hybrid FRP-steel-reinforced concrete beams

2019 ◽  
Vol 23 (7) ◽  
pp. 1290-1304
Author(s):  
Yang Yang ◽  
Ze-Yang Sun ◽  
Gang Wu ◽  
Da-Fu Cao ◽  
Zhi-Qin Zhang
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Concrete Beams ◽  
Reinforced Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Hybrid Fiber ◽  
Steel Reinforced Concrete ◽  
Reinforced Polymer ◽  
The Cross

This study presents a design method for hybrid fiber-reinforced-polymer-steel-reinforced concrete beams by an optimized analysis of the cross section. First, the relationships among the energy consumption, the bearing capacity, and the reinforcement ratio are analyzed; then, the parameters of the cross section are determined. Comparisons between the available theoretical and experimental results show that the designed hybrid fiber-reinforced-polymer-steel-reinforced concrete beams with a low area ratio between the fiber-reinforced polymer and the steel reinforcement could meet the required carrying capacity and exhibited high ductility.

scholarly journals GENERAL CASE OF REINFORCED CONCRETE ROD ELEMENTS CALCULATION USING THE DIAGRAM METHOD

2021 ◽  
Vol 93 (1) ◽  
pp. 26-37
Author(s):  
O.V. RADAYKIN ◽  
◽  
L.S. SABITOV ◽  
L.SH. AKHTYAMOVA ◽  
T.P. ARAKCHEEV ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Longitudinal Force ◽  
Internal Force ◽  
The Other ◽  
Bending Moments ◽  
Diagram Method ◽  
The Cross ◽  
Three Components

In SP 63.13330 the general calculation case for the diagram method is oblique off-center compression, which takes into account only three components of internal force factors in the cross section: the longitudinal force-Nz – and two bending moments relative to the corresponding axes – Mx and My. The other three components-the QX and Qy transfer forces and the MZ torque – are left out of consideration. In addition, for this case, the search in the available literature, including the founders of the diagram method, for the output of calculation formulas was not successful – in all sources they are given in ready-made form without evidence. This article is intended to try to fill in these gaps. For this purpose, based on the expressions for rod displacements that are generally accepted in mechanics, in particular on the Mora integral of displacements, the resolving expressions of the diagram method are obtained in the most general form.

scholarly journals Application of Nanoindentation and 2D and 3D Imaging to Characterise Selected Features of the Internal Microstructure of Spun Concrete

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1016 ◽  
Author(s):  
Jarosław Michałek ◽  
Michał Pachnicz ◽  
Maciej Sobótka
Keyword(s):  
Cross Section ◽  
Longitudinal Axis ◽  
Concrete Mixture ◽  
Wall Structure ◽  
Outer Side ◽  
Micro Computed Tomography ◽  
Concrete Element ◽  
The Cross ◽  
Paste Content ◽  
Spun Concrete

The spinning of concrete is a process in which concrete mixture is moulded and compacted under the action of the centrifugal force arising during the fast rotational motion of the mould around its longitudinal axis. As a result of the spinning of the liquid concrete mixture, an element annular in cross section, characterised by an inhomogeneous layered wall structure, is produced. The heavier constituents tend towards the cross-section wall’s outer side, while the lighter components tend towards its inner side. The way in which the particular constituents are distributed in the element’s cross section is of key importance for the macro properties of the manufactured product. This paper presents procedures for investigating spun concrete and interpreting the results of such investigations, which make it possible to characterise the microstructure of the concrete. Three investigative methods were used to assess the distribution of the constituents in the cross section of the element: micro-computed tomography (µCT), 2D imaging (using an optical scanner) and nanoindentation. A procedure for interpreting and analysing the results is proposed. The procedure enables one to quantitatively characterise the following features of the microstructure of spun concrete: the mechanical parameters of the mortar, the aggregate content, the pore content, the cement paste content, the aggregate grading and the size (dimensions) of the pores. Special attention is devoted to the determination of the variation of the analysed quantities in the cross section of the element. The result of the application of the investigative procedures is presented for an exemplary spun concrete element. The proposed procedures constitute a valuable tool for evaluating the process of manufacturing spun concrete elements.

scholarly journals Manufacturing of fiber-reinforced concrete bridge arches

2021 ◽  
Vol 48 (3) ◽  
pp. 99-105
Author(s):  
M. R. Nakhaev
Keyword(s):  
Reinforced Concrete ◽  
Cross Section ◽  
Bending Moment ◽  
High Strength ◽  
Fiber Reinforced Concrete ◽  
Concrete Bridge ◽  
Fiber Reinforced ◽  
Reinforced Concrete Bridge ◽  
The Cross ◽  
High Strength Fiber

Objective. A new method of manufacturing arches for a fiber-reinforced concrete bridge in the form of an analogue of permanent formwork is considered. Within the framework of this work, research results have been obtained that confirm the effectiveness of the system for the construction of bridge arches of various configurations.Method. The proposed developments will improve the strength characteristics of the bridge arch for small and medium bridges by optimizing the shape and size of the cross section in accordance with the change in the bending moment along the length of the arch. At the same time, reduce its metal consumption by several times.Result. The results obtained confirmed the effectiveness of electrostatic spraying of dry concrete mixture with simultaneous moisture up to moisture, which contributes to the work of capillary forces for compaction of concrete layers and the manufacture of a profiled strong shell (analogue of non-removable reinforced formwork) from reinforced fiber-reinforced concrete.Conclusion. By varying the shape and dimensions of the cross- section, the thickness of the shell and the degree of its reinforcement, as well as filling this shell with high-strength fiber-reinforced concrete, it is possible to design and manufacture bridge arches for various loads.

scholarly journals APPLICATION OF STEPWISE AND ITERATIVE METHOD IN THE CALCULATION OF BENDING PRESTRESSED PRECAST AND MONOLITHIC ELEMENTS TAKING INTO ACCOUNT PHYSICAL NONLINEARITY

2020 ◽  
pp. 12-27
Author(s):  
Polina Davidenko ◽  
Yasser Garib Sami ◽  
Andrey Shevchenko
Keyword(s):  
Reinforced Concrete ◽  
Iterative Method ◽  
Cross Section ◽  
Rational Design ◽  
Variational Principles ◽  
Structural Mechanics ◽  
Physical Nonlinearity ◽  
Method Of Calculation ◽  
Existing Structures ◽  
The Cross

precast and monolithic reinforced concrete structures with and without prestressing armature voltages are used as newly designed independent ones, and are the result of work to strengthen existing structures by increasing the cross section. In both cases, the cross-section of such elements is considered as a two-layer, and the resulting composite element operates under load in conditions distributed between the layers of internal forces, the mechanism and the actual value of the distribution of which depends on the physical and mechanical characteristics, the design scheme and the parameters of the contact interaction of the layers. When calculating and designing prestressed reinforced concrete precast and monolithic elements, the shear seam compliance is usually not taken into account, which complicates the analysis of the actual stress-strain state of the structure and contains a certain undisclosed potential for its rational design. One of the possible directions in solving the problem, taking into account the shift of the contact seam, is the use of variational principles of structural mechanics in the calculation of structures such as composite cross-section rods. In the framework of this work, the questions of practical applicability in the structural analysis of composite reinforced concrete precast-monolithic rod of variation principles of structural mechanics based on the method of V.Z. Vlasov – I.E. Mileykovsky in the form of displacements in combination with the stepwise-iterative method of calculation are considered. The results of numerical calculations by the proposed method are presented, which allows to take into account the specifics of the shear bonds of the precast and monolithic layer, to carry out practical accounting of the seam compliance, as well as to take into account the physical nonlinearity of the characteristics of materials, which allows the rational design of precast monolithic structures.

Sign in / Sign up

Export Citation Format

Share Document