Deformation of Steel-Reinforced Concrete Round Thin Slabs Taking into Account the Compliance of the Support Contour

2021 ◽  
Vol 887 ◽  
pp. 680-690
Author(s):  
Kh.S. Razzokov
Keyword(s):  
Reinforced Concrete ◽  
Stress State ◽  
Strain State ◽  
Experimental Studies ◽  
Concrete Slabs ◽  
Governing Equations ◽  
Short Term ◽  
Steel Reinforced Concrete ◽  
Normalized Parameters

The paper presents the governing equations of bending of nonlinearly deformable, axisymmetrically loaded round, thin reinforced concrete and steel concrete slabs, taking into account the work of a non-deformable and pliable support contour. Based on the results of theoretical and experimental studies, the stress-strain state of reinforced concrete and steel-concrete slabs under short-term and long-term loadings was estimated. The nature of stress state is revealed in the stages of cracking and destruction of plates. The work of the slabs in the field of elastic, elastoplastic and plastic stages of work is estimated. Using the method of limiting equilibrium, a method for calculating steel-concrete slabs for strength with normalized parameters.

scholarly journals Determination of features of composite steel and concrete slab behavior under fire condition

2021 ◽  
Vol 6 (7 (114)) ◽  
Author(s):  
Valeriia Nekora ◽  
Stanislav Sidnei ◽  
Taras Shnal ◽  
Olga Nekora ◽  
Iryna Dankevych ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Temperature Distribution ◽  
Fire Resistance ◽  
Temperature Regime ◽  
Strain State ◽  
Concrete Slabs ◽  
Standard Temperature ◽  
Steel Reinforced Concrete ◽  
Steel Sheets ◽  
Reinforced Concrete Slabs

Methods for calculating the fire resistance of steel-reinforced concrete slabs made using profiled steel sheets under the influence of a standard temperature regime for more than 120 minutes are considered and analyzed. Research has been carried out to determine the heating parameters and the stress-strain state of steel-reinforced concrete slabs made using profiled steel sheets under fire conditions for more than 120 minutes. The results of this study allow to obtain indicators of temperature distribution for assessing the fire resistance of such structures for fire resistance classes above REI 120. Accordingly, the results obtained are a scientific basis for improving the existing method for calculating the fire resistance of steel-reinforced concrete slabs made using profiled steel sheets. The temperature distribution in the cross-section of structures was obtained using a general theoretical approach to solving the problem of heat conduction using the finite element method. Using the obtained temperature distributions, the parameters of the stress-strain state were determined based on the method of limiting states. To carry out the calculations, appropriate mathematical models were created that describe the effect of the standard temperature regime of a fire, to determine the temperature distribution at every minute in the sections of steel-reinforced concrete slabs with profiled steel sheets. A method is proposed for dividing the section into zones to take into account the decrease in the indicators of the mechanical properties of concrete and steel. A simplified method for the design assessment of steel-reinforced concrete slabs made using profiled steel sheets is proposed, which is consistent with the current EU standards and can be effectively used to analyze their fire resistance when establishing their compliance with the fire resistance class REI 120 and higher.

Improvement Of Curvilinear Diagrams Of Concrete Deformation

2019 ◽  
pp. 99-104
Keyword(s):  
Reinforced Concrete ◽  
Peak Load ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Deformation Model ◽  
Reinforced Concrete Structures ◽  
Significant Difference ◽  
Deformation Diagrams

Problems when calculating reinforced concrete structures based on the concrete deformation under compression diagram, which is presented both in Russian and foreign regulatory documents on the design of concrete and reinforced concrete structures are considered. The correctness of their compliance for all classes of concrete remains very approximate, especially a significant difference occurs when using Euronorm due to the different shape and sizes of the samples. At present, there are no methodical recommendations for determining the ultimate relative deformations of concrete under axial compression and the construction of curvilinear deformation diagrams, which leads to limited experimental data and, as a result, does not make it possible to enter more detailed ultimate strain values into domestic standards. The results of experimental studies to determine the ultimate relative deformations of concrete under compression for different classes of concrete, which allowed to make analytical dependences for the evaluation of the ultimate relative deformations and description of curvilinear deformation diagrams, are presented. The article discusses various options for using the deformation model to assess the stress-strain state of the structure, it is concluded that it is necessary to use not only the finite values of the ultimate deformations, but also their intermediate values. This requires reliable diagrams "s–e” for all classes of concrete. The difficulties of measuring deformations in concrete subjected to peak load, corresponding to the prismatic strength, as well as main cracks that appeared under conditions of long-term step loading are highlighted. Variants of more accurate measurements are proposed. Development and implementation of the new standard GOST "Concretes. Methods for determination of complete diagrams" on the basis of the developed method for obtaining complete diagrams of concrete deformation under compression for the evaluation of ultimate deformability of concrete under compression are necessary.

Long-Term Deformations of Strengthened Reinforced Concrete Linear Elements

2016 ◽  
Vol 691 ◽  
pp. 51-60 ◽  
Author(s):  
Martin Krizma ◽  
Lubomir Bolha
Keyword(s):  
Reinforced Concrete ◽  
Long Term Results ◽  
Short Term ◽  
Limit States ◽  
Linear Elements ◽  
Repeated Load ◽  
The Moment ◽  
Concrete Elements ◽  
Fiber Fabric

The issue of strengthening the damaged linear reinforced concrete elements have been engaged since 2008. We focused on the analysis of resistance and the characteristics of limit states of serviceability in the damaged and subsequently strengthened elements at a short-term loading. In the introduction phase, the strengthening of the elements was carried out with the following procedures – installation of an overlayer on the coupling board or a combination of the board and use of glass – fiber fabric (GFRP). The strengthening was also affected by the type of contact (reinforced/non-reinforced) – the deformed element/coupling board and its effect on resistance, type of deformation and serviceability. In the non-reinforced contact, we applied some of the types of adjustments to the surface of the strengthened element. At the moment, we are dealing with the effects of time and repeated load on the strengthened elements. The results correspond to the reinforced contact. The values are compared with the short-term results of the strengthened beams and with the long-term results of the beams prepared for strengthening.

scholarly journals Nonlinear creep in a steel-reinforced concrete beam

2020 ◽  
Vol 17 (5) ◽  
pp. 108-116
Author(s):  
S. O. Chepilko ◽  
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Reinforced Concrete Beams ◽  
Nonlinear Creep ◽  
Short Term ◽  
Nonlinear Integral Equations ◽  
Steel Reinforced Concrete ◽  
Linear Creep ◽  
Resolving System

Problems of taking into account nonlinear creep in steel- reinforced concrete beams are considered basing on the integral equation of viscous-elastic-plasticity of concrete. There has been obtained the resolving system of nonlinear integral equations, a linearization of this system has been carried out, its asymptotic solutions have been written out for the theory of elastic heredity case. The analysis of taking into account nonlinear creep has been performed compared with the linear creep equations and an instantaneous (short-term) loading allowing for concrete’s nonlinear diagram.

Effects of short- and long-term treatments of sardine (Sardina pilchardus) protein hydrolysates on blood lipid concentrations and antioxidant status, in rats fed cholesterol-enriched diets

2022 ◽  
Vol 11 (6) ◽  
pp. 733-745
Author(s):  
Nora Athmani ◽  
Allaoui Amine ◽  
Nasri Moncef ◽  
Boualga Ahmed
Keyword(s):  
Experimental Studies ◽  
Blood Lipid ◽  
Protein Hydrolysates ◽  
High Cholesterol ◽  
Short Term ◽  
Hypercholesterolemic Diet ◽  
Short And Long Term ◽  
Antioxidant Enzymes Activities ◽  
Radical Attack

Hypercholesterolemia is a major risk factor of cardiovascular diseases (CVD). A limited number of experimental studies have shown that sardine protein hydrolysates (SPH) could be a very useful natural compound to prevent hy-percholesterolemia by both improving the lipoprotein profile and modula-ting oxidative stress. In the present study, the effect of short and long term treatments with SPH were examined on serum lipid contents, lipid peroxida-tion and antioxidant enzymes activities in rats fed cholesterol-enriched diet. At day 0, rats were divided into five groups. The group of day 0 was the stan-dard group, and the four remaining groups were divided into two parts of two groups each consuming for 14 or 28 days an hypercholesterolemic diet, and treated (HC-SPH) or not (HC) by gavage with SPH. Compared with day 0, serum TC contents were increased at day 14 and remained unchanged at day 28 in HC-SPH group. These values were decreased in HC-SPH versus HC. Liver and heart TBARS concentrations were increased at day 14 then diminished at day 28 in HC-SPH group. Liver and heart SOD and CAT activities were decrea-sed at short term then remained unchanged at long term in HC-SPH group. In addition, these activities were enhanced in HC-SPH versus HC. In conclusion, these results indicate the potential effects of short and long term treatments of SPH to improved cholesterolemia and reduced radical attack in rats fed high-cholesterol diets.

Experimental studies on continuous reinforced concrete slabs under single and multi-compartment fires with cooling phase

2020 ◽  
Vol 111 ◽  
pp. 102915 ◽  
Author(s):  
Yong Wang ◽  
Jiachao Wu ◽  
Zhaohui Huang ◽  
Jian Jiang ◽  
Guanglin Yuan ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Experimental Studies ◽  
Concrete Slabs ◽  
Compartment Fires ◽  
Reinforced Concrete Slabs ◽  
Cooling Phase
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