scholarly journals Features of strengthening metal structures with composite materials under the influence of an aggressive environment

Vestnik MGSU ◽  
2020 ◽  
pp. 496-509
Author(s):  
Anna N. Leonova ◽  
Oleg D. Sofyanikov ◽  
Irina A. Skripkina
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Bearing Capacity ◽  
Galvanic Corrosion ◽  
Practical Experience ◽  
Building Structures ◽  
Metal Structures ◽  
Aggressive Environment ◽  
External Reinforcement ◽  
Fiber Materials

Introduction. This article is devoted to the issues of reinforcing metal building structures with external reinforcement systems with composite materials. The application of these strengthening methods in domestic literature and in practice has not been fully studied. As a result, it is relevant to study the characteristics of strengthening under the action of an external aggressive environment, namely when exposed to galvanic corrosion, elevated ambient temperatures and extreme temperatures from firing. The purpose of the study is to establish the effectiveness of reinforcing metal structures with composite materials under the influence of various force factors, including cyclic loads, and under the action of an external aggressive environment. Materials and methods. The methodological basis of scientific research was the analysis of publications of domestic and foreign scientists on the theoretical and practical experience of using composite materials to strengthen metal structures. During the study, when describing the dependences of physical quantities on external and internal force and non-force factors, scientific methods of induction, deduction, generalization and comparison were used. Results. Performed a comprehensive study of the effectiveness of the use of composite materials to enhance the metal structures in hostile environments. The dependence of the increase in strength of reinforced steel samples on the length of the adhesive joint of external reinforcement is analyzed, the possibility of applying reinforcement at fatigue stresses is investigated. Recommendations on the use of protective insulating systems and materials that prevent the reduction of the bearing capacity of structures from external non-force factors are given. Conclusions. The effectiveness of reinforcing metal structures using composite carbon fiber materials is revealed. The bearing capacity of reinforced structures may be increased by 59 %. When the glass transition temperature of carbon fiber materials is reached, the increase in the bearing capacity from external amplification systems decreases by 50 %, and when the temperature is increased to 60 °C, the external amplification systems are ineffective and do not increase the bearing capacity. To achieve the required fire resistance of the amplification systems, equal to at least one hour, it is necessary to use external fire insulation.

scholarly journals The Use of Mathematical Modelling Methods in the Creation of Composite Materials Based on Carbon Fibre Materials

2021 ◽  
Vol 1203 (2) ◽  
pp. 022093
Author(s):  
Valery Varentsov ◽  
Valentina Kuzina ◽  
Alexander Koshev ◽  
Valentina Varentsova
Keyword(s):  
Mathematical Modeling ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Solid Phase ◽  
Electrochemical Modification ◽  
Electrochemical Parameters ◽  
Solutions Of Electrolytes ◽  
The Creation ◽  
Fiber Materials ◽  
Electrodeposition Of Metals

Abstract The report provides data on the electrochemical modification of carbon-graphite fibers as the basis for the creation of composite materials. The results of studies of the electrodeposition of metals on pre-electrochemically modified carbon fiber materials (CFM) in order to obtain composite materials based on them are presented. The use of CFM for the creation of composite materials is associated with the possibility of deposition of metals, alloys or their compounds on the surface of their constituent fibers. Electrochemical treatment in aqueous solutions of electrolytes is a promising method for modifying the surface properties of carbon materials, including in order to improve their adhesive properties. Preliminary electrochemical modification of carbon fiber materials in indifferent solutions of electrolytes made it possible to obtain composite and nanocomposite materials with good adhesion of the electrodeposited metal to the surface of the fibers of carbon materials.When metals are deposited on carbon fiber materials, it is necessary to solve the problem of applying a uniform metal deposit or with a certain profile in the thickness of the material. In this case, it is effective to use methods of mathematical modeling of metal deposition processes in a flowing three-dimensional electrode. Depending on the selected modes of deposition of metal sediment on the CFM, some electrochemical parameters of the process and system may be dependent on both the time of the process and the thickness coordinate of the electrode. This is especially true for the value of the resistivity of the solid phase of the system, that is, carbon-graphite fibrous material. Other electrochemical parameters, such as the specific electrode surface, the exchange current and the transfer coefficient of the electrochemical reaction, the porosity of the material, etc., can also change during the electrodeposition of the metal on the CFM. It is proposed to take into account the change in the characteristic properties of modified carbon fiber materials in the mathematical modeling of the processes of electrodeposition of metals on carbon fiber materials in order to determine the technological parameters to improve the efficiency of the properties of composite materials. In order to implement mathematical models used in the calculation of electrochemical processes in the volume and on the surface of carbon fiber materials, a set of programs based on modern computational methods and programming languages has been developed.

scholarly journals Сomparative analysis of the methods of strengthening of masonry, metal structures, reinforced concrete, such as traditional methods and the alternative methods of strengthening by FRP-materials

2020 ◽  
pp. 267-291
Author(s):  
Iryna Rudnieva
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Alternative Methods ◽  
Building Structures ◽  
Traditional Methods ◽  
External Appearance ◽  
Metal Structures ◽  
Advantages And Disadvantages ◽  
Heritage Buildings ◽  
Determining Factor

Built mostly centuries ago, heritage buildings as well the more contemporary buildings of the last century, which have lost the bearing capacity often need restoration and strengthening, especially in seismic regions and in regions with shrinkage phenomena (subsidence region). The need of strengthening of the building constructions during exploitation appears mostly because of their premature wear as a result of technological influences and weathering, various damage and various other factors. Traditional methods of strengthening are effective, but in some cases not appropriate or not applicable  for use. An example is the increase of the load-bearing structures of historical buildings, preserving the external appearance of which is the determining factor. In this case, the use of the discussed alternative methods can be justified alternative. Knowledge of the causes of defects and damage of structures allows to choose the best option of repairing or strengthening. The aim of the research is the evaluation of the structural performance of composite fibre-reinforced elements in the wider sector of the conservation of historical, architectonic and environmental heritage, as well the more contemporary buildings of the last century, which have lost of the bearing capacity focusing reliability indexes and the appearance of the structure. In the article was described and analyzed the existing traditional methods and the alternative methods of strengthening by FRP-materials (composite materials) such building structures as masonry, metal structures, reinforced concrete, and the computation in software ABAQUS. These procedures of strengthening building structures by FRP-materials  in Ukraine are not widely used due to the lack of a regulatory framework that would regulate their use, as well because these materials are relatively expensive compared to the traditional ones. The article analyzed the existing methods of computation and design of the strengthening using FRP-materials, and the computation in software ABAQUS was performed with conclusions and recommendations based on results of the computation. The aim of the work was to review the technology and analyze the advantages and disadvantages of each of the strengthen methods that should be used when choosing effective solutions for strengthening building structures. In conclusion, the need for further study and researches was confirmed.

Shear Behavior Of Anchors On The Basis Of Carbon Fiber At External Reinforcement

2019 ◽  
pp. 59-64
Keyword(s):  
Carbon Fiber ◽  
Bearing Capacity ◽  
Carbon Fibers ◽  
Experimental Studies ◽  
Shear Forces ◽  
External Reinforcement ◽  
Concrete Body ◽  
Improve Calculation ◽  
Analysis Of Results ◽  
The Impact

In systems of external reinforcement on the basis of carbon fibers used for strengthening concrete structures, special attention should be paid to the anchoring of carbon reinforcement elements. Taking into account their installation in the external reinforcement system in the reinforced structure, the anchoring elements can work on the shear. At the same time, the nature of such operatioj as a whole is insufficiently studied, which raises many questions both about their calculation and their design. In order to improve calculation and design methods of carbon anchors, special experimental studies of the parameters of anchors and their impact on the bearing capacity of the anchor fastening were carried out. These studies relate to the length of the anchorage in the concrete body, maximum shear forces, ultimate deformations of the anchor etc. According to the results of the experiments conducted, the analysis of results obtained was performed, in particular, various schemes of destruction of anchors were analyzed and the impact of the depth of the anchor, its diameter of the anchor, as well as the type of binder on the degree of theirdestruction were studied.

scholarly journals Reinforcement of concrete by composite materials

2018 ◽  
Vol 149 ◽  
pp. 01046
Author(s):  
Bensaid Boulekbache ◽  
Mostefa Hamrat ◽  
Nejma Imane Gacem ◽  
Kheltoum Halimi
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Mechanical Behavior ◽  
Bearing Capacity ◽  
Experimental Work ◽  
Failure Modes ◽  
Confined Concrete ◽  
Clear Indication ◽  
Bending Loading ◽  
Behavior Strength

This work was devoted to the material-scale study of the mechanical behavior of confined concrete by composite materials based on carbon fiber and glass under compression and bending loading. In this context, an experimental work on cylindrical and prismatic concrete specimens has been carried out. The obtained results permitted the identification of the mechanical behavior, strength, deformability and failure modes. The outcome of the present research indicates an increase in the bearing capacity and deformability in compression and in tension. The reinforcement by means of composite materials appears as a pertinent solution and therefore, makes it possible to obtain clear indication on the type of confinement to be considered according to the intended purpose.

scholarly journals An integrated approach to the use of composite materials for the restoration of reinforced concrete structures

2019 ◽  
Vol 135 ◽  
pp. 03068 ◽  
Author(s):  
Vladimir Rimshin ◽  
Pavel Truntov
Keyword(s):  
Reinforced Concrete ◽  
Composite Materials ◽  
Bearing Capacity ◽  
Concrete Structures ◽  
Integrated Approach ◽  
Reinforced Concrete Structures ◽  
Technical Inspection ◽  
Concrete Layer ◽  
External Reinforcement ◽  
Calculation Results

The article presents the results of a technical inspection of the state of the structures of the object. To conduct the study, horizontal structures of the sludge pool that were exposed to the carbonization reaction were taken for the objects under investigation. Defects and damages of the considered structures revealed during visual inspection are described. The degree of carbonization of reinforced concrete structures was determined by the phenolphthalein sample method. According to the results of the technical inspection, a verification calculation of the beam was carried out in order to determine its bearing capacity for assessing the suitability for further operation after restoration and strengthening. The calculation was performed using software. Based on the calculation results, data on the bearing capacity of the beam reinforced with composite materials were determined. The option of restoring and strengthening the beam using external reinforcement based on carbon fibers FibArm 230/150 is presented. The restoration was carried out taking into account the carbonized concrete layer. Based on the results of the study, an assessment is given of the application of an integrated approach to the restoration and strengthening of structures with composite materials, taking into account the carbonized concrete layer.

Theoretical Assessment Of The Bearing Capacity Of A Steel Beam Reinforced With Carbon Fiber

2020 ◽  
pp. 18-22
Keyword(s):  
Carbon Fiber ◽  
Bearing Capacity ◽  
Adhesive Layer ◽  
Carbon Plastic ◽  
Steel Beams ◽  
Steel Beam ◽  
Fiber Plastic ◽  
Fiber Materials ◽  
Short Time ◽  
Theoretical Assessment

To reinforce steel beams, modern carbon fiber materials that are attached to the beam from the stretched side using a special two-component adhesive can be effectively used. Compared to traditional methods of cross-section increase by means of additional steel elements attached by welding or on bolts, reinforcing with carbon fiber plastic has a number of advantages. Carbon plastic has a much smaller weight than a steel element that has the same load-bearing capacity; the adhesive layer prevents corrosion of the reinforced element; work on strengthening is carried out in a short time and with less labor expenditures etc. The article presents the results of theoretical studies of beams reinforced with carbon fiber lamellas. For the theoretical assessment of the strength of a reinforced steel beam, deformations and stresses in the section at the elastic, elastic-plastic and plastic stages of steel work are considered. It is established that a significant effect of carbon fiber reinforcement is observed even when the stresses in it are determined by the strength of the adhesive joint. Formulas, taking into account the strength of the adhesive layer determined experimentally, for determining the strength of a reinforced beam are obtained. A theoretical model of the operation of bent steel elements is constructed and theoretical dependencies are obtained that can be used for calculations of steel beams reinforced with carbon plastic.

scholarly journals NUMERICAL AND EXERIMENTAL MODELING OF RIGID JOINT OF LAYERED WOODEN STRUCTURES

2017 ◽  
Vol 13 (2) ◽  
pp. 84-92
Author(s):  
Mikhail A. Vodiannikov ◽  
Galina G. Kashevarova
Keyword(s):  
Composite Materials ◽  
Carbon Fiber ◽  
Bearing Capacity ◽  
Contact Problems ◽  
Continuous Beam ◽  
Structural Failure ◽  
Ansys Software ◽  
Software Complex ◽  
Wooden Structures

The article deals with the problems of modeling and solving contact problems in the ANSYS software complex using the example of calculating the rigid joint of a glued wooden beam. Comparative calculation data for a continuous beam and a beam with a joint in the middle on pasted carbon fiber nails are given. The possibilities of using contact elements between different materials taking into account the nonlinearity of the formulation of the problem are described. The figures of stresses and displacements in the elements are shown. Experiments for determination of the bearing capacity of the joint and determine the nature of structural failure are provided. Conclusions are made about the possibility of modeling composite materials in the environment of the software complex ANSYS in the real structures design

scholarly journals Research of technical and economic indicators of reinforcement of reinforced concrete beams by different technologies

2020 ◽  
pp. 144-153
Author(s):  
О. Molodid ◽  
I. Maksymiuk ◽  
A. Hryhorova
Keyword(s):  
Carbon Fiber ◽  
Bearing Capacity ◽  
Fiber Reinforcement ◽  
Economic Indicators ◽  
Design Solution ◽  
Labor Intensity ◽  
Rigid Support ◽  
Carbon Fiber Reinforcement ◽  
External Reinforcement ◽  
Technical And Economic Indicators

The article presents the results of experimental investigations to determine the destructive force of beams reinforced with external reinforcement and control (without reinforcement). According to the results of such investigations, it can be stated that the strengthening of beam structures by external reinforcement made it possible to increase their bearing capacity by 383.3%. It has been established that both carbon fiber reinforcement using "clamps" and carbon fiber reinforcement are effective.The performed analytical researches established technical and economic indicators of various methods of reinforcement of beam constructions, namely: the addition of additional supports, the addition of additional beams, the external reinforcement of stretched zones by MAPEI technology. As a result, data were obtained indicating that the reinforcement of the crossbar by bringing additional rigid support requires 110.4 man-hours (100%), the reinforcement of the crossbar by bringing additional beams - 94.4 man-hours (85.5%), the reinforcement of the crossbar by external reinforcement - 48 man-hours (43.5%). In this case, the reinforcement of the crossbar by bringing additional rigid support is performed in 9.7 days (100%), the reinforcement of the crossbar by bringing additional beams - 6 days (62%), the reinforcement of the crossbar by external reinforcement - 4 days (41.4%). It is also established that the reinforcement of the crossbar by bringing additional rigid support costs 51.8 thousand UAH (100%), strengthening the structure by bringing additional beams - 58.1 thousand UAH (112%), strengthening the structure by external reinforcement - 35.72 thousand UAH (68.9%).The obtained research results indicate that the labor intensity, duration and cost of reinforcing the beam with external reinforcement is lower compared to other technologies. Efficiency is achieved by a structural component - increasing the bearing capacity without changing the design solution and by technological component - reducing the labor intensity, duration and cost of work.

Bearing Capacity of Restored and Strengthened Reinforced Concrete Floor Slabs

2020 ◽  
pp. 21-27
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
High Efficiency ◽  
Raw Materials ◽  
Experimental Studies ◽  
Building Structures ◽  
Concrete Floor ◽  
Reinforced Concrete Slabs ◽  
Floor Slabs ◽  
External Reinforcement

The influence of various repair compositions on the bearing capacity of restored and strengthened floor slabs modeling flat reinforced concrete floor slabs of communication collectors is considered. Industrial brands of repair compositions based on cement binder, repair compositions containing quartz sand and mixing water after treatment with low-temperature non-equilibrium plasma, and materials for external reinforcement of building structures were used. It is shown that industrial repair compositions based on cement and repair compositions based on modified raw materials restore the bearing capacity of model floor slabs in almost the same way. In this case, the destruction of floor slabs occurs on the repair composition. It was established that the external reinforcement of reinforced concrete slabs restored with repair compositions using carbon mesh or tape significantly increases their bearing capacity. The high efficiency of the use of epoxy polymer composite materials for the repair and strengthening of reinforced concrete structures of various functional purposes is confirmed by the results of verification calculations of the initial and model floor slabs, as well as conducted experimental studies.

Calculation Method of Flexural Bearing Capacity of Carbon Fiber Reinforced Concrete Beam

2011 ◽  
Vol 71-78 ◽  
pp. 5080-5083
Author(s):  
Le Zhou ◽  
Hong Tao Liu
Keyword(s):  
Reinforced Concrete ◽  
Carbon Fiber ◽  
Bearing Capacity ◽  
Concrete Beam ◽  
Reinforced Concrete Beam ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Flexural Bearing Capacity ◽  
Carbon Fiber Reinforced ◽  
Fiber Materials

To study further mechanical behavior of flexural members of carbon fiber reinforced concrete, this text uses the methods of fiber materials composite principles and balance equations, and derives the elastic modulus of the carbon fiber concrete. The acting principle of carbon fiber in the concrete is analyzed. Based on three bearing stages of carbon fiber reinforced concrete beam, the calculation formulas to flexural bearing capacity of carbon fiber reinforced concrete are given. It is theoretical basis of implication of carbon fibers in civil engineering.

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