scholarly journals Heat Engineering Heterogeneity Of The Outer Walls Of Earthquake-Resistant Buildings

2020 ◽  
Vol 02 (12) ◽  
pp. 1-8
Author(s):  
Shipacheva E.V. ◽  
◽  
Pirmatov R. Kh. ◽  
Turdalieva M.K. ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Thermal Protection ◽  
Experimental Studies ◽  
Heat Fluxes ◽  
Heat Engineering ◽  
Earthquake Resistant ◽  
Aerated Concrete ◽  
Shielding Properties ◽  
Heat Shielding ◽  
Concrete Elements

When assessing the level of energy efficiency of civilian buildings, a special place is given to establishing the level of thermal protection of their external enclosing structures. Significant discrepancies in the results of theoretical and experimental studies of heat fluxes through the outer walls of buildings erected in seismic areas are associated with the design features of fences - the presence of reinforced concrete elements in them: anti-seismic belts at the level of floors, cores at intersections of walls and along the edges of large window openings ... In addition, in recent years, external walls have become widespread, which are filling of bricks or aerated concrete blocks between the main structural elements of the frame - monolithic reinforced concrete columns and crossbars. The introduction of reinforced concrete elements into the structure of the external wall fencing provides strength, rigidity and stability of buildings, guarantees its seismic resistance. At the same time, reinforced concrete inclusions are significant “cold bridges” in warmer brick or aerated concrete masonry. Such heat engineering heterogeneity of earthquake-resistant outer walls significantly complicates the process of determining their heat-shielding properties. This, in turn, leads to errors in the design of heating systems, which inevitably affects the thermal comfort of the premises, the formation of condensation and mold zones in the cold zones of the inner surface of the fences. The article presents the results of theoretical and experimental studies to determine the heat-shielding properties of external heat-engineering heterogeneous walls of earthquake-resistant buildings. The most reliable method for calculating the reduced resistance to heat transfer of an inhomogeneous external structure and the coefficient of its thermal inhomogeneity have been established.

scholarly journals MATHEMATICAL MODELING OF DESTRUCTION OF FIBERGLASS-BASED THERMAL-PROTECTION MATERIAL

2020 ◽  
pp. 71-78
Author(s):  
D.Ya. Barinov ◽  
◽  
P.S. Marakhovskij ◽  
A.V. Zuev ◽  
◽  
...  
Keyword(s):  
Thermal Protection ◽  
Experimental Studies ◽  
Thermophysical Characteristics ◽  
Capsule Type ◽  
Typical Trajectory ◽  
Material Sample ◽  
Heat Shielding ◽  
Physical And Mathematical Models ◽  
The Mathematical Model ◽  
Shielding Material

The paper proposes physical and mathematical models of heat and mass transfer in fiberglass used as a destructive heat-shielding material for capsule type descent vehicles. To provide the mathematical model with the initial data, experimental studies of the thermophysical characteristics of the material and the kinetic parameters of destruction have been carried out. There has been made a simulation of the destruction of a material sample during descent in the Earth's atmosphere along a typical trajectory for various areas of the heat shield; as a result, the dependences of temperatures on the flight time and the depth of the coked layer have been determined.

Using of Plastic Hinges in the Calculation of Buildings against Progressive Collapse under Fire Exposure

2018 ◽  
Vol 878 ◽  
pp. 115-120
Author(s):  
Levon Avetisyan
Keyword(s):  
Reinforced Concrete ◽  
Progressive Collapse ◽  
Experimental Studies ◽  
Fire Exposure ◽  
Reinforced Concrete Frame ◽  
Dynamic Calculation ◽  
Plastic Hinges ◽  
Concrete Frame ◽  
In Fire ◽  
Concrete Elements

This article presents a study of the strength of a 25-storey reinforced concrete frame against progressive collapse in fire conditions. Taking into account the angles of disclosure of plastic hinges as norming for the strength of reinforced concrete elements, a computer technology program has been developed and included in PR Wolfram Mathematica 10 for the dynamic calculation of compressed reinforced concrete elements under fire exposure on the basis of the conducted experimental studies. Dynamic calculation of the strength of eccentrically compressed reinforced concrete columns was carried out, with operation in normal conditions and under high temperatures. The diagram «moment-curvature» and the graph of the change of the static and dynamic strength of the column depending on the temperature were developed. Nonlinear dynamic analysis of a 25-storey reinforced concrete frame was conducted, taking into account the changes of the dynamic characteristics of reinforced concrete elements in fire and, the estimation of resistance of the frame was given.

scholarly journals Design Model Of Bending Reinforced Concrete Elements Under Action Of Transverse Forces Under Conditions Of Increased And High Temperatures

2020 ◽  
Vol 02 (10) ◽  
pp. 17-24
Author(s):  
Mahkamov Y.M. ◽  
Keyword(s):  
Reinforced Concrete ◽  
Crack Resistance ◽  
High Temperatures ◽  
Experimental Studies ◽  
Calculation Model ◽  
Design Model ◽  
Stress Strain ◽  
Concrete Elements

In this article, the calculation of the strength and crack resistance of bending elements operating under conditions of high and high temperatures and transverse forces are proposed to be carried out according to a calculation model developed based on an analysis of experimental studies that takes into account more correctly the physics of the stress-strain phenomenon of the element.

scholarly journals Improved engineering method for calculating the strength of the supporting areas of reinforced concrete elements

2018 ◽  
Vol 230 ◽  
pp. 02014 ◽  
Author(s):  
Olena Krantovska ◽  
Mykola Petrov ◽  
Liubov Ksonshkevych ◽  
Sergii Synii ◽  
Pavlo Sunak
Keyword(s):  
Reinforced Concrete ◽  
Comparative Analysis ◽  
Cross Sections ◽  
Experimental Studies ◽  
Engineering Calculation ◽  
Standard Methods ◽  
Refined Method ◽  
Eurocode 2 ◽  
The World ◽  
Concrete Elements

According to the results of experimental studies, empirical dependencies were obtained (obtained from the appropriate mathematical models). The advanced (refined) method of engineering calculation of express-estimation of the strength of sloping cross sections of elements of flexible reinforced concrete structures on the basis of comparative analysis of the obtained empirical dependencies and standard accepted methods in the world was developed (nine basic norms are taken: DSTU B.V.2.6-156:2010 (Ukraine), previously operating SNiP 2.03.01-84*, SNB 5.03.01-02 (Belarus), SR 63.13330.2012 (Russia), Eurocode 2, 2004 (European Union), ACI 318-M14 (USA), AIJ Code, 2007 (Japan), CSA 23.3-04 (Canada), DIN 1045-1 (Germany). The coefficient of variation of bearing capacity and accident ratio according to the results of calculations of standard methods are determined. Their comparative analysis is carried out and informative graphic figures are presented.

scholarly journals Numerical and experimental studies of bent elements of basalt fiber reinforced concrete with prestressed glass composite reinforcement under static and short-term dynamic loads

2019 ◽  
Vol 221 ◽  
pp. 01026
Author(s):  
Vasilii Plevkov ◽  
Konstantin Kudyakov
Keyword(s):  
Reinforced Concrete ◽  
Experimental Studies ◽  
Basalt Fiber ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Dynamic Effects ◽  
Glass Composite ◽  
Short Term ◽  
Concrete Elements ◽  
Composite Reinforcement

The article shows studies of bending basalt fiber reinforced concrete elements with pre-stressed glass composite reinforcement under static and short-term dynamic effects. Main results of numerical and experimental studies are presented. It is experimentally established and theoretically confirmed that a significant increase in the strength and crack resistance of the normal sections of concrete bent elements is observed when using basalt fiber reinforcement and pre-stressed glass composite reinforcement.

scholarly journals ANALYSIS OF STRENGTHENING OF COMPRESSED REINFORCED CONCRETE STRUCTURES USING REINFORCED CONCRETE JACKETS / GNIUŽDOMŲJŲ GELŽBETONINIŲ KONSTRUKCIJŲ STIPRINIMO GELŽBETONINIAIS APVALKALAIS ANALIZĖ

2011 ◽  
Vol 3 (2) ◽  
pp. 76-84
Author(s):  
Saulius Pilkavičius
Keyword(s):  
Reinforced Concrete ◽  
Carrying Capacity ◽  
Theoretical Calculations ◽  
Experimental Studies ◽  
Calculation Methods ◽  
Advantages And Disadvantages ◽  
Calculation Algorithms ◽  
Capacity Calculation ◽  
Basic Equations ◽  
Concrete Elements

This article investigates two chosen calculation methods of compressed reinforced concrete elements strengthened using reinforced concrete jackets. Shortly describe carrying capacity calculation algorithms of these calculation methods. Present elements basic equations and dependences of carrying capacity. For calculation methods of carrying capacity comparison and adjustment executed carrying capacity experimental studies of compressed fiber reinforcement concrete elements strengthened using reinforcement concrete jackets. Were compared theoretical calculations of carrying capacity results with experimental carrying capacity results. Shortly describe advantages and disadvantages of analyzed calculation methods and experimental research. By the comparison of calculation methods conclusions and experimental studies conclusions, produces improved calculation method of carrying capacity.

Strength of Normal and Inclined Sections of Bent Reinforced Concrete Elements with Zone Reinforcement Made of Steel Fiber

2022 ◽  
Vol 906 ◽  
pp. 7-15
Author(s):  
Dmitry Utkin
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Loading ◽  
Calculation Method ◽  
Steel Fiber ◽  
Experimental Studies ◽  
Concrete Structures ◽  
Dynamic Loads ◽  
Reinforced Concrete Structures ◽  
Short Term ◽  
Concrete Elements

On the basis of theoretical and experimental studies, the prerequisites and the method of calculation of bent and compressed-curved reinforced concrete structures with zone reinforcement made of steel fiber, working under static and short-term dynamic loads, are formulated. In the developed method for calculating the strength of normal and inclined sections, a nonlinear deformation model is implemented, which is based on the actual deformation diagrams of materials. The developed calculation method is brought to the program of calculation of reinforced concrete structures with zone reinforcement of steel fiber under short-term dynamic loading, taking into account the inelastic properties of materials. The numerical studies made it possible to determine the influence of various parameters of steel-fiber reinforcement on the strength of reinforced concrete elements. To confirm the main results of the developed calculation method, experimental studies of reinforced concrete beam structures reinforced with conventional reinforcement and a zone steel-fiber layer are planned and carried out. Experimental studies were carried out under static and short-term dynamic loads. As a result of the conducted experiments, data were obtained that characterize the process of destruction, deformation and cracking of steel-reinforced concrete elements under such types of loading. The dependences of changes in the energy intensity of reinforced concrete structures with zone reinforcement made of steel fiber in the compressed and stretched cross-section zones under dynamic loading are obtained. The effectiveness of the use of fiber reinforcement of normal and inclined sections of bent and compressed-curved elements to improve the strength and deformative.

THE INFLUENCE OF PLASTIC STRAINS ON THE BEHAVIOR OF BENDING REINFORCED CONCRETE ELEMENTS WHEN CHANGING THE FORCE SIGN

2021 ◽  
Vol 98 (6) ◽  
pp. 50-62
Author(s):  
S.O. KURNAVINA ◽  
◽  
I.K. MANAENKOV ◽  
I.V. TSATSULIN ◽  
◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Experimental Tests ◽  
Plastic Strains ◽  
Limit Values ◽  
State Bearing ◽  
Reverse Loading ◽  
Earthquake Resistant ◽  
Capacity Reduction ◽  
Concrete Elements

The Russian standards for earthquake resistant constructions suppose the development of plastic strains in reinforced concrete constructions under seismic effects. Their presence influences significantly on the stress-strain state, bearing capacity and mechanism of destruction of reinforced concrete constructions under alternation loads of high intensity. The methodology and main results of experimental tests connected with the evaluation of plastic deformations influence on the behavior of reinforced concrete bending elements when changing the force sign is represented. The information about the bearing capacity reduction when changing the force sign with the increase of plastic strains in the first semi cycle of loading is given. The coefficients of plasticity for reinforcement deformations limit values are obtained, corresponding to the beginning of compressed zone concrete destruction when changing the force sign and the plots of normal sections deformations distribution of experimental specimens under direct and reverse loading have been built.

scholarly journals EXPERIMENTAL STUDIES ON THE INFLUENCE OF TRANSVERSE REINFORCEMENT FOR STRENGTH OF COMPRESSED REINFORCED CONCRETE ELEMENTS

2021 ◽  
Vol 10 (4) ◽  
pp. 21-28
Author(s):  
Sergey S. MORDOVSKIY ◽  
Kamil B. SHARAFUTDINOV
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Experimental Studies ◽  
Longitudinal Force ◽  
Concrete Sample ◽  
Transverse Reinforcement ◽  
Direct Factor ◽  
Rectangular Cell ◽  
Concrete Elements ◽  
Zigzag Type

The infl uence of transverse reinforcement, including indirect reinforcement, on the strength of compressed reinforced concrete elements is analyzed. This question arose in connection with the possibility of increasing the strength of short reinforced concrete elements loaded with a longitudinal force with small eccentricities within the section of the element. For such elements, the cage eff ect may appear, associated with the coeffi cient of transverse deformations, the magnitude of which is a direct factor in the destruction of the concrete sample, and the limitation of these directly aff ects the bearing capacity of the sample in the direction of increase. The infl uence of transverse reinforcement in the form of stirrups located with diff erent spacing, as well as indirect reinforcement in the form of meshes with a classical rectangular cell and meshes of the “zigzag” type is considered.

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