To Determination of Stresses in the Stretched Armature of Extracredly Compressed Elements in the Limit Condition

2019 ◽  
Vol 974 ◽  
pp. 556-563
Author(s):  
Evgeniy N. Peresypkin ◽  
Sergey E. Peresypkin
Keyword(s):  
Reinforced Concrete ◽  
Linear Dependence ◽  
Boundary Value ◽  
Limit State ◽  
Limit Condition ◽  
Equal Strength ◽  
Points Of View ◽  
Concrete Elements

The problem of determining stresses in a stretched reinforcement of inflexible eccentric-compressed reinforced concrete elements is considered when the height of the compressed zone in the limit state exceeds its boundary value corresponding to the condition of equal strength of the section. Instead of the generally accepted linear dependence of the stresses under consideration on the height of the compressed zone, an elliptic relationship more expedient from different points of view has been proposed.

scholarly journals Analyzing of Coatings on Steel - Reinforced Concrete Elements by Mobile NMR

2016 ◽  
Vol 62 (1) ◽  
pp. 65-82 ◽  
Author(s):  
J. Orlowsky
Keyword(s):  
Reinforced Concrete ◽  
Potential Effect ◽  
Building Site ◽  
Steel Reinforced Concrete ◽  
Mobile Nmr ◽  
The Individual ◽  
First Time ◽  
Concrete Elements ◽  
Non Destructive

Abstract A large number of infrastructural concrete buildings are protected against aggressive environments by coating systems. The functionality of these coating systems is mainly affected by the composition and thickness of the individual polymeric layers. For the first time ever, a mobile nuclear magnetic resonance (NMR) sensor allows a non-destructive determination of these important parameters on the building site. However, before this technique can be used on steel-reinforced concrete elements, the potential effect of the reinforcement on the measurement, i.e. the NMR signal, needs to be studied. The results show a shift of the NMR profile as well as an increase of the signals amplitude in the case of the reinforced samples, while calculating the thickness of concrete coating leading to identical results.

scholarly journals TO DETERMINATION OF THE CRACKING MOMENT FOR BENDING REINFORCED CONCRETE ELEMENTS WITH ACCOUNT OF PLASTIC DEFORMATIONS OF CONCRETE IN THE TENSION AREA

2018 ◽  
Vol 3 (3) ◽  
pp. 30-38
Author(s):  
О.В. Радайкин ◽  
Oleg Radaykin
Keyword(s):  
Reinforced Concrete ◽  
Deformation Model ◽  
Conventional Concrete ◽  
Class A ◽  
Standard Calculation ◽  
Plasticity Coefficient ◽  
Concrete Elements ◽  
Nonlinear Deformation Model ◽  
Good Agreement

At the standard calculation of the cracking moment for bending reinforced concrete elements the plasticity coefficient γ is normally used, which according to SP 63.13330.2012 is 35% less than in the old SNiP 2.03.01-84*. The question arises, what is the reason for such a noticeable difference and which of the methods gives more reliable results? This article seeks to answer this question. For this purpose the physical meaning of the coefficient γ was considered in detail, with the usage of a nonlinear deformation model of a normal section. A calculation formula for γ depending on an element’s reinforcement degree was obtained, which is valid for conventional concrete of B15-B35 class. A comparison of the calculated cracking moment according to the proposed method with experiments by the other authors was carried out. A good agreement of results was observed.

scholarly journals Strength criterion for a plane stress reinforced concrete element under a special action

Vestnik MGSU ◽  
2020 ◽  
pp. 1513-1522
Author(s):  
Natalia V. Fedorova ◽  
Vu Ngoc Tuyen ◽  
Igor A. Yakovenko
Keyword(s):  
Reinforced Concrete ◽  
Progressive Collapse ◽  
Concrete Strength ◽  
Limit State ◽  
Strength Criterion ◽  
Structural Systems ◽  
Variable Loading ◽  
Concrete Element ◽  
Theory Of Plasticity ◽  
Concrete Elements

Introduction. Problem solving focused on the protection of buildings and structures from progressive collapse and minimization of resources, needed for this purpose, is becoming increasingly important. In many countries, including Russia, this type of protection is incorporated into national regulatory documents, and, therefore, any research, aimed at developing effective ways to protect structural systems from progressive collapse under special actions, is particularly relevant. In this regard, the present article aims to formulate effective strength criteria for such anisotropic materials as reinforced concrete to analyze plane stressed reinforced concrete structures exposed to sudden structural transformations caused by the removal of one of bearing elements. Materials and methods. To solve this problem, a variant of the generalized theory of plasticity of concrete and reinforced concrete, developed by G.A. Geniev, is proposed for application to the case of variable loading of a plane stressed reinforced concrete element. The acceptability of generalization of the strength criterion, pursuant to the theory of plasticity of concrete and reinforced concrete under static loading, and the applicability of this criterion to variable static-dynamic loading of reinforced concrete are used as the main hypothesis. An algorithm of an approximate method is presented as a solution to this problem; it allows to analyze the considered stress-strain state of plane stressed reinforced concrete elements. Results. The numerical analysis of the obtained solution, compared with the results of the experimental studies, was used to evaluate the designed strength criterion for reinforced concrete elements located in the area where the column is connected to the girder of a monolithic reinforced concrete frame in case of a sudden restructuring of a structural system. It is found out that the qualitative nature of the destruction pattern of the area under research, obtained in experiments, corresponds to the destruction pattern, identified by virtue of the analysis performed using the proposed criterion. Conclusions. The variant of the reinforced concrete strength criterion designated for the variable loading of a plane stressed reinforced concrete element and an algorithm for its implementation, based on the theory of plasticity of concrete and reinforced concrete developed by G.A. Geniev, is applicable to the analysis of a special limit state of reinforced concrete elements of structural systems of frames of buildings and structures.

scholarly journals ASSESSMENT OF THE DEPTH AND RATE OF CORROSION IN STEEL REINFORCEMENT OF REINFORCED CONCRETE CULVERTS

2020 ◽  
Author(s):  
Alexandr Vasiliev ◽  
Svetlana Daškevič
Keyword(s):  
Reinforced Concrete ◽  
Protective Layer ◽  
Corrosion Damage ◽  
Steel Reinforcement ◽  
Operating Conditions ◽  
Protective Properties ◽  
Open Atmosphere ◽  
Concrete Elements ◽  
Corrosion State

Based on the results of many research years on concrete carbonisation: both immediately after manufacture (using heat-moisture treatment) and in reinforced concrete elements operated for the periods of various length (in an open atmosphere); the effect of carbonisation on the change in the protective properties of concrete in relation to steel reinforcement; for determination of the dependence of the corrosion state of steel reinforcement on the degree of concrete carbonisation in the area of steel reinforcement; the obtained regression dependences of the change (by time in the cross section) of the degree of concrete carbonisation of various classes in strength, – the analysis of the time of the onset of the boundary values of the degrees of concrete carbonisation (strength classes C12/15–C30/37) for the operating conditions of the open atmosphere was performed. Based on it, the regression dependences of the time variation of the depth of corrosion damage of steel reinforcement were construed (for fixed thicknesses of the concrete protective layer). The obtained nature of dependences made it possible to offer, in a general form, the regression dependences of the depth of corrosion damage and corrosion rate of steel reinforcement for concretes (strength classes C12/15–C30/37) for operating conditions in open atmosphere.

scholarly journals DETERMINATION OF REGULATORY RELIABILITY FOR DEFORMATION OF REINFORCED-CONCRETE FLEXIBLE STRUCTURES

2019 ◽  
Vol 21 (5) ◽  
pp. 115-126
Author(s):  
E. P. Gerasimov
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
Structural Reliability ◽  
Limit State ◽  
Flexible Structures ◽  
Probabilistic Methods ◽  
Methods Of Calculation ◽  
State Method ◽  
Definition Of

Strength, stiffness, crack resistance requirements must be specified for any structure. These requirements are provided by the appropriate calculations. Compliance with all requirements ensures the design reliability. But due to the fact that structural analysis is performed by the limit state method, the numerical value of the reliability cannot be determined. This can be done only by applying probabilistic methods of calculation. One of the major obstacles to the use of probabilistic methods is the lack of standardized values of the structural reliability (normative reliability).Although probabilistic methods of calculation were developed in late in the 20th century, the assignment of normative reliability values encountered serious obstacles. The most serious obstacle was the consideration of the failure consequences as some consequences were quantifiable. On the other hand, much work concerned the assignment of normative structural reliability based on their bearing capacity. Only few works related to the reliability normalization using deformation and crack resistance.This paper deals with the regulatory definition of reliability using the deformation of reinforced-concrete bendings based on physiological requirements. A method for determining the normative reliability based on human sensitivity to fluctuations is proposed. The normative reliability of precast slabs is determined using the proposed method.

Special Limit Condition Of Reinforced Concrete Structures And Its Normalization

2020 ◽  
pp. 4-9
Keyword(s):  
Reinforced Concrete ◽  
Limit State ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Functional Requirements ◽  
Limit States ◽  
Limit Condition ◽  
Load Bearing ◽  
Significant Strength ◽  
Special Limit

One of the ways to improve the resilience of buildings in the event of failure of the bearing structure or emergency, seismic effects is a more complete account of the behavior of elements and their mates at short-term action of loads and dynamics of change of the scheme of the bearing system of the building. To do this, it is advisable to allow more cracks to open, the development of deflections and partial destruction of some sections, which contradicts the current criteria for the first and second limit states that ensure the operational suitability of structures and buildings. Therefore, it is necessary to introduce specific standards of a special limit state for structures. A special limit state is the stage of operation of the structure after reaching the load-bearing capacity for the first and the deformation limits for the second limit states. Exceeding this state, in which the structures do not fully meet the functional requirements, leads to their collapse. The implementation of this limit state is most appropriate in load-bearing systems with a high degree of static indeterminability and constructive interaction of all bearing elements. The introduction and consideration of a special limit stress-strain state of reinforced concrete structures make it possible to detect significant strength and deformation reserves, even after significant fragmentation of the compressed concrete zone and, as a result, reducing the working section of the structure. As the main criteria of a particular limit state for reinforced concrete structures, it is recommended to adopt: the ultimate deformations of compressed concrete and tensile reinforcement with higher values than permissible under normal conditions; as well as the deflections of elements, provided that the minimum allowable length of the zone of bearing and anchorage of reinforcement.

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