scholarly journals Experimental research methodology crack opening width of reinforced concrete elements

2006 ◽  
Vol 27 (1) ◽  
Author(s):  
В.И. Колчунов ◽  
Масуд Нур Эддин
Author(s):  
Olena Vasylivna Romashko-Maistruk ◽  
Vasyl Mykolayovych Romashko

The article highlights the most important studies results of the mechanism of normalcracks formation and opening in stretched reinforced concrete elements during their deformation. Acritical analysis of the existing methods and ways for calculating normal cracks level formation andopening, in which the reinforcement to concrete adhesion is taken into account directly or indirectly,is carried out. The main advantages and disadvantages of each of these methods are indicated. It hasbeen experimentally confirmed that the crack formation process is generally leveled. The mainfeatures and patterns of cracking in stretched reinforced concrete elements and structures arerevealed. The main characteristics of the prototypes are given, according to the test results of whichit was established that in practical calculations of the reinforced concrete elements crack resistance,it is usually possible to restrict oneself to two levels of normal cracking. For the indicated crackinglevels, the corresponding load level, step and crack opening width are established. The expediencyof using in practical calculations the nonlinear function of the reinforcement with concrete averageadhesion stresses is also substantiated. Based on the studies results carried out, the existing methodsfor calculating the normal cracks formation and opening in reinforced concrete elements andstructures were evaluated from the standpoint of local disadvantage of the reinforcement to concreteadhesion.General and simplified methods for calculating normal cracks level formation and opening inreinforced concrete elements have been developed. In them, the direct integration of the expressionfor the concrete and reinforcement mutual displacements is proposed to be replaced not by thenumerical integration of the indicated expression, but by the successive accumulation of the indicateddisplacements. Corresponding statistical comparisons of the calculations results by these methodswith experimental data are carried out. The effectiveness of the developed methods for calculatingnormal cracks level formation and opening by comparing them with existing methods is estimated.


Author(s):  
S. Merkulov ◽  
E. Akimov

The inability of using this type of reinforcement as a cross on the support sections of the bent elements is one of the reasons limiting the wide use of composite rod reinforcement. To ensure the strength of bent elements along inclined sections, it is proposed to bend the rods of the working longitudinal working reinforcement, and geometric parameters of bends for some types of composite reinforcement are proposed, depending on the diameter of the rod. To develop a method for calculating the strength of inclined sections, it is necessary to develop experimentally justified prerequisites that take into account the features of joint operation of composite rod reinforcement in inclined sections. The article offers a method for experimental study of the strength and crack resistance of reinforced concrete bending elements with non-metallic composite rod reinforcement, including the design of prototypes, the installation scheme of devices during testing. The developed method allows to determine the parameters of strength and crack resistance of inclined sections of bent elements. The tasks of experimental studies of concrete elements reinforced with composite rod reinforcement are to determine the regularity of changes in the stress-strain condition of concrete and composite reinforcement during loading, to determine the nature of the destruction of elements along the inclined section, to obtain data on the strength and crack resistance of elements.


2018 ◽  
Vol 7 (3.2) ◽  
pp. 275
Author(s):  
Тatiana Nikiforova ◽  
Olga Gukasian ◽  
Nataliia Mahas

In this work the experimental research cycle is described. This cycle is an affect studying of the most widespread concrete defect types, such as concrete core weakening is an inclusion of the "weak" concrete, the presence of emptiness, concrete heterogeneous by the height. The research of the manufacturing conditions affect of combine concrete core structures and the elements of physical and mechanical characteristics changing are on the experimental research base. On the researches testing base of samples with special form and given sizes the concrete strength value is appreciated. The different variants of strength decreasing on the researched element height are analyzed by the conducted testing results of the steel reinforced concrete structures. As a result of the conducted tests, the work conditions coefficient and the steel reinforced concrete elements concreting technology were formulated.  


2019 ◽  
Vol 974 ◽  
pp. 614-619
Author(s):  
Valeria A. Pshenichkina ◽  
Fedor F. Leychu ◽  
Kseniya N. Sukhina ◽  
Vyacheslav V. Drozdov

The article discusses the methodology for the reinforced concrete structures’ probabilistic deformation calculation. The uniform deformation criteria for assessing the reliability of reinforced concrete structures in the operation stage for strength, stiffness and crack opening are proposed. Taking into consideration the relatively high degree of heterogeneity of reinforced concrete as a building material, each criterion is determined with a predetermined provision.


2021 ◽  
Vol 3 (2) ◽  
pp. 64-74
Author(s):  
I. Korneieva ◽  
◽  
D. Kirichenko ◽  
O. Shyliaiev ◽  
◽  
...  

The results of experimental studies of deformability and crack resistance of models of aerodrome slabs made of reinforced concrete and steel-fiber concrete, made on the basis of serial slab PAG-18 taking into account the scale factor, are presented. Two series of slabs were tested - two models of reinforced concrete and two models with one-percent dispersed reinforcement. The load was applied in steps, the instrument readings were recorded twice at each step and the crack opening width was measured starting from the moment of the first crack formation. Dial gauges, deflectometer and microscope MPB-3 were used as measuring instruments. In accordance with the normative documents acting in Ukraine, one of two possible loading schemes was considered - with the loading by the concentrated force applied in the span part of a plate which had a hinged support along its short sides. Plate models were tested on a specially made stand. Each load step ended with a five-minute dwell time, at the beginning and the end of which readings were taken on the measuring instruments. The deformations at the same levels were measured with dial gauges. The process of crack formation was observed with a Brinell tube in the places of the greatest crack opening. Breaking load for fiber concrete slab was 1.52 times higher than for reinforced concrete slab, and the moment of cracking initiation was 1.22 times higher. The process of cracking in the fiber concrete slab begins at higher loads than in the reinforced concrete slab. The initial crack opening width of the slabs is almost the same, and the final crack opening width of all the cracks in the fiber concrete slab is significantly lower than in the reinforced concrete slab. The deformations in steel-fiber concrete slabs when the load is applied in the span, both for compressed and stretched fibers, are higher than in reinforced concrete slabs. The experimental studies indicate that dispersed reinforcement of airfield slabs with steel fiber leads to their higher crack resistance.


2018 ◽  
Vol 230 ◽  
pp. 02028 ◽  
Author(s):  
Vasyl Romashko ◽  
Olena Romashko

The separate experimental investigations results and the major drawbacks of existing methods of calculating the reinforced concrete elements crack resistance are considered in detail, taking into account the process of multilevel formation and crack opening. Based on the basic provisions of the deformation and strength model of concrete and reinforced concrete resistance, an engineering method for calculating the formation and disclosure of normal cracks in the reinforced concrete elements and structures at the operational stages of their deformation is proposed. It is implemented on the system of generally accepted static, geometric and physical relations of a deformed solid mechanics. The simplicity of the proposed calculation method is due to the use of the nonlinear function of the average stresses of the reinforcement bond with concrete on the sections of the reinforced concrete element between adjacent cracks. The main advantages of the developed calculation method in comparison with others are outlined.


Author(s):  
Л. Р. Маилян ◽  
С. А. Стельмах ◽  
Е. М. Щербань ◽  
М. П. Нажуев

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.


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