scholarly journals MODERN STEEL-CONCRETE SPAN STRUCTURES OF SMALL AND MEDIUM-SPAN BRIDGES

2021 ◽  
pp. 25-34
Author(s):  
Roman Kaplin
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Automatic Welding ◽  
Reinforced Concrete Slab ◽  
Load Bearing ◽  
Metal Elements ◽  
Advantages And Disadvantages ◽  
Concrete Girder

The paper reviews the most common reinforced concrete girder structures of modern bridges used in Ukraine and other countries. The scope, advantages and disadvantages of reinforced concrete structures are considered. The peculiarities of the use of reinforced concrete structures in European countries are reviewed. The most common typical structural solutions of reinforced concrete girder structures used worldwide are given. Options for facilitation of reinforced concrete structures without significant loss of load-bearing capacity are also highlighted. Options for facilitation of structures are presented in the article by lightening the metal load-bearing elements and reducing the weight of the reinforced concrete slab of the carriageway. Reducing the weight of metal elements can be obtained through the use of perforated elements, which can be performed by waste-free technology. To reduce the cost of materials and reduce the weight of the reinforced concrete slab, it is designed lightweight – hollow or ribbed. When removing concrete from the stretched zone, only the ribs of the width required to accommodate the welded frames and ensure the strength of the panels on an inclined cross section are retained. In this case, the plate in the span between the ribs work on the bend as beams of T-section. The top shelf of the plate also works on the local bend between the ribs. During the inspection, the article presents a new design of reinforced concrete girder structure, using perforated box metal elements, made by waste-free technology, and lightweight reinforced concrete slab of the carriageway with hollow formers. Metal blocks are connected to each other by bolts. Metal blocks are made of perforated sheet elements made of waste-free technology. Each block consists of two main beams, transverse diaphragms and a lower plate. The upper belt of the main beams is implemented with the device of horizontal shelves along the entire length of the beams, performing the function of a supporting element for the reinforced concrete slab. Combining all structural elements into a single finished unit is carried out in the factory by automatic welding, which, in turn, allows us to achieve the high factory readiness. The diaphragms of the block are made with a comb along the upper border, on which a profiled steel sheet is placed, which is a fixed formwork for a reinforced concrete slab. The plate is made of non-removable formwork. To ensure the joint operation of the metal part and the reinforced concrete slab, a system of discrete-continuous connections in the form of rigid stops connected in the longitudinal and transverse directions by reinforcing rods is proposed.

scholarly journals APPLICATION OF ARTIFICIAL NEURAL NETWORKS FOR ASSESSING THE REINFORCEMENT OF REINFORCED-CONCRETE FLOOR SLABS

2019 ◽  
Author(s):  
A. Liashkevich
Keyword(s):  
Neural Networks ◽  
Artificial Neural Networks ◽  
Reinforced Concrete ◽  
Concrete Slab ◽  
Concrete Structures ◽  
Building Design ◽  
Reinforced Concrete Structures ◽  
Reinforced Concrete Slab ◽  
Artificial Neural

In this article the problem of assessment of working documentation quality in terms of trustworthiness of the calculation of area of main reinforcement of reinforced-concrete structures is reviewed. In spite of development of automated designing systems, no application solutions for fully automated check of quality of working documentation for reinforced-concrete structures as regards sufficiency and necessity of reinforcement of them have been proposed until now. Moreover, this rather routine procedure can be fully automated to exclude the subjective nature of its results. Artificial neural networks (ANN) constitute the most promising mathematical model for this purpose. There are known examples demonstrating the possibility of applying the ANN for various types of calculations and analysis of experimental data for reinforced-concrete structures. In particular, the ANN allows predicting the actual deformation parameters of reinforced-concrete structures with significantly greater accuracy than any of the current national design standards. The article presents the results of calculations of reinforcement and sag for various input parameters using the example of reinforced-concrete slab structure. Using the simplest ANN with one hidden layer over the entire training sample, the predicted values with sufficient accuracy for practical use were obtained. It has been established that ANN makes it possible to predict effectively not only values of the required reinforcement for slab structures, but also their deformation. Within the framework of BIM-technologies used currently in building design, the use of ANN to assess the quality of ready-made design documentation in terms of reinforcement will reduce considerably the cost and time of relevant examinations with significantly higher trustworthiness of their results.В статье рассмотрена задача оценки качества рабочей документации в части достоверности расчета площади рабочей арматуры железобетонных конструкций. Несмотря на развитие систем автоматизированного проектирования, до настоящего времени не предложено прикладных решений для полностью автоматизированной проверки качества рабочей документации железобетонных конструкций на предмет достаточности и необходимости их армирования. При этом эта весьма относительно рутинная процедура может быть полностью автоматизирована для исключения субъективного характера ее результатов. Наиболее перспективной математической моделью для этой цели являются искусственные нейронные сети (ИНС). Известны примеры, демонстрирующие возможность прикладного применения ИНС для различного рода расчетов и анализа экспериментальных данных для железобетонных конструкций. В частности, ИНС позволяет с существенно большей точностью прогнозировать фактические параметры деформирования железобетонных конструкций, чем любые из действующих национальных норм проектирования. В статье на примере железобетонной плитной конструкции приведены результаты расчетов армирования и прогиба при различных значениях входных параметров. С помощью простейшей ИНС с одним скрытым слоем по всей обучающей выборке получены прогнозные значения с достаточной для практического их использования точностью. Установлено, что ИНС позволяет достаточно эффективно прогнозировать не только значения требуемого армирования для плитных конструкций, но и их деформации. В рамках используемых в настоящее время в строительном проектировании BIM-технологий применение ИНС для оценки качества готовой проектной документации в части армирования позволит значительно сократить стоимость и сроки соответствующих экспертиз при существенно более высокой достоверности их результатов.

scholarly journals Methodology for Assessing the Probability of Corrosion in Concrete Structures on the Basis of Half-Cell Potential and Concrete Resistivity Measurements

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Lukasz Sadowski
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Electrochemical Techniques ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Half Cell ◽  
Reinforced Concrete Slab ◽  
Cell Potential ◽  
Potential Measurement ◽  
Concrete Resistivity

In recent years, the corrosion of steel reinforcement has become a major problem in the construction industry. Therefore, much attention has been given to developing methods of predicting the service life of reinforced concrete structures. The progress of corrosion cannot be visually assessed until a crack or a delamination appears. The corrosion process can be tracked using several electrochemical techniques. Most commonly the half-cell potential measurement technique is used for this purpose. However, it is generally accepted that it should be supplemented with other techniques. Hence, a methodology for assessing the probability of corrosion in concrete slabs by means of a combination of two methods, that is, the half-cell potential method and the concrete resistivity method, is proposed. An assessment of the probability of corrosion in reinforced concrete structures carried out using the proposed methodology is presented. 200 mm thick 750 mm  ×  750 mm reinforced concrete slab specimens were investigated. PotentialEcorrand concrete resistivityρin each point of the applied grid were measured. The experimental results indicate that the proposed methodology can be successfully used to assess the probability of corrosion in concrete structures.

scholarly journals Corrosion protection of reinforcing steel reinforced concrete structures of transport structures

2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Alexander Bulkov ◽  
Michail Baev ◽  
Igor Ovchinnikov
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Protection ◽  
Concrete Structures ◽  
Steel Corrosion ◽  
High Strength ◽  
Curing Temperature ◽  
Reinforced Concrete Structures ◽  
Reinforcing Steel ◽  
Steel Reinforced Concrete ◽  
Advantages And Disadvantages

The influence of reinforcing steel corrosion on the durability of reinforced concrete structures of transport structures and the degree of knowledge of this problem is considered. It is specified that the protection of reinforcing steel from corrosion is not able to completely replace the correct design and use of high-strength concrete. But it is able to extend the life of reinforced concrete structures. It is noted that corrosion of the reinforcement leads to a decrease in the structural strength due to wear and tear and by a third of the period of operation of reinforced concrete structures, as a result of which transport structures collapse. As an example of the detrimental effect of corrosion of reinforcing steel on the durability of transport structures, examples of accidents of bridges and overpasses caused by this type of corrosion are given. As a result, a conclusion is drawn on the advisability of ensuring a sufficient level of corrosion protection of reinforcing steel to achieve the required durability of reinforced concrete structures of transport structures. The types and causes of corrosion processes in reinforcing steel reinforced concrete structures are described. The compositions and technologies of anticorrosive protection are examined and analyzed. Comparison of the compositions of anticorrosive protection of reinforced concrete structures is carried out according to the following criteria: consumption, density, viability, curing temperature and the number of components of the composition. A comparison of anti-corrosion protection technologies is carried out on the basis of the following indicators: line dimensions, productivity and consumption of energy resources. A comparison is also made of the cost of using various anti-corrosion protection technologies. Based on the data obtained, the advantages and disadvantages of the considered compositions and technologies of corrosion protection are determined. As a result, the most effective and technologically advanced method of corrosion protection of steel reinforcement of reinforced concrete structures of transport structures is selected.

Steel-Reinforced Concrete Floors With The Use Of Bent Steel Profiles

2020 ◽  
pp. 10-14
Keyword(s):  
Reinforced Concrete ◽  
Concrete Slab ◽  
Concrete Strength ◽  
Theoretical Research ◽  
Steel Beams ◽  
Reinforced Concrete Structure ◽  
Reinforced Concrete Slab ◽  
Steel Reinforced Concrete ◽  
Advantages And Disadvantages ◽  
Concrete Strengthening

The issues of designing a steel-reinforced concrete floor using bent steel profiles are considered. The steel-reinforced concrete flooring consists of a monolithic reinforced concrete slab arranged on a removable formwork, and steel bent profiles. The removable formwork during the concreting process rests on steel beams without additional mounting posts in the floor span. Steel beams accept the weight of the formwork and concrete during the pouring, working on bending. After concrete strengthening, they mainly work on stretching as part of composite steel-reinforced concrete structure. The article has identified the advantages and disadvantages of steel-reinforced concrete flooring with the use of light steel thin-walled bent profiles. Checking the strength of the beam at the concreting stage and evaluating the load-bearing capacity of the floor after the concrete strength is set confirm the performance of this structure. Using the regulatory methodology for SP 266.1325800.2016, the area of implementation of steel and concrete flooring with CFS beams and the nomenclature of applied steel beams have been established. For practical application of the presented design, it is recommended to conduct experimental and theoretical research and develop engineering methods.

scholarly journals A variety of designs construction and mounting

2019 ◽  
Vol 135 ◽  
pp. 02022
Author(s):  
Tamara Danchenko ◽  
Anatoly Lastovka ◽  
Sergey Amelchugov ◽  
Nadezhda Klinduh ◽  
Maria Berseneva
Keyword(s):  
Reinforced Concrete ◽  
Concrete Structures ◽  
High Strength ◽  
Climatic Conditions ◽  
Reinforced Concrete Structures ◽  
Building Structures ◽  
Metal Structures ◽  
Advantages And Disadvantages ◽  
Building Designs ◽  
Wooden Structures

Abstract in the article the main types of building structures are considered, which are distinguished by the type of material. For the purpose of studying, each type has brief information including its advantages and disadvantages in comparison with others. In the section reinforced concrete structures, the authors characterize this material from three sides - this is the method of manufacture, the type of concrete and its stressed state. As a result, it was found that when choosing a foundation, special attention is paid to: bearing capacity, type of building being built, soil characteristics. In addition to the above, it can be added that weight reduction, cost reduction and material consumption in reinforced concrete structures are possible through the use of high-strength concrete and reinforcement. Metal structures are the most popular building material. The possibilities of this material are very diverse: building designs, designs specifically for certain seismic and climatic conditions, and high decorative properties. Due to its strength and rigidity, buildings can withstand hurricane gusts of wind and earthquakes. In the manufacture of structures in the factory and during installation, steel is subjected to various technological operations: welding, cutting, machining. It was found that in this case the steel does not collapse, it retains the microstructure and mechanical properties. Finally, steel should not have a significant cost of manufacturing structures from it. Turning to the section of wooden structures, the authors list the main advantages - it is comfortable and environmentally friendly and material.

scholarly journals Biological Corrosion Inhibitors for Concrete

2021 ◽  
pp. 183-203
Keyword(s):  
Reinforced Concrete ◽  
Corrosion Inhibitors ◽  
Concrete Structures ◽  
Life Forms ◽  
Reinforced Concrete Structures ◽  
Chemical Corrosion ◽  
Advantages And Disadvantages ◽  
Biological Corrosion ◽  
Structural Engineers ◽  
Green Corrosion Inhibitors

Corrosion in the reinforced concrete structures is a promising concern for material and structural engineers. Chemical corrosion inhibitors are usually suggested by the corrosion specialists in this regard, which adds an enormous amount of cost to the total materials charges and some are harmful to life forms. Therefore, some green corrosion inhibitors are introduced in this study which are relatively cheaper and holds good compatibility with concrete. We have highlighted the mechanisms of protection, advantages and disadvantages of different green biological corrosion inhibitors by broadly categorizing them into two types. This classification is based on the origin and mechanism of corrosion inhibition of the respective class. The first class is microbial inhibitors which prevent the onset of corrosion by making biofilms and precipitating calcite on steel surface and concrete voids respectively. And the second class is of botanical inhibitors which are the extracts of plants and protect the steel bars by forming biofilms. So both of the biological inhibitors are efficient to eliminate the corrosion of reinforced concrete structures.

scholarly journals Nonlinear calculation of reinforced concrete structures to the impact of the air shock wave

Vestnik MGSU ◽  
2019 ◽  
pp. 33-45 ◽  
Author(s):  
Anton Y. Savenkov ◽  
Oleg V. Mkrtychev
Keyword(s):  
Numerical Simulation ◽  
Shock Wave ◽  
Reinforced Concrete ◽  
Nonlinear Dynamic ◽  
Software Package ◽  
Crack Opening ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Advantages And Disadvantages ◽  
The Impact

Introduction. Researched methods of accounting for the nonlinear operation of reinforced concrete structures on the example of an industrial structure, when exposed to an air shock wave using modern software systems based on the finite element method. The calculation of reinforced concrete construction to the impact of an air shock wave, if no increased requirements for tightness are presented to it, in accordance with current regulatory documents, must be carried out taking into account the elastic-plastic work, crack opening in the stretched zone of concrete and plastic deformations of reinforcement are allowed. Reviewed by new coupling approach to determining the dynamic loads of a shock wave, implemented in the LS-DYNA software package, which allows to take into account the effects of a long-range explosion and wave-wrapping around a structure. Materials and methods. The study of the stress-strain state of the structures was carried out using numerical simulation. For the nonlinear equivalent-static method, a step-by-step calculation algorithm is used, with gradual accumulation and distribution of stresses, implemented in the LIRA-SAPR software package. For the nonlinear dynamic method, the Lagrangian-Eulerian formulation is used using the methods of gas dynamics in the LS-DYNA software package. Results. As a result of numerical simulation, the following was done analysis of existing methods of nonlinear calculations; analysis of the existing loads during the flow of shock waves around the structure; analysis of the forces and movements in the bearing elements, as well as pictures of the destruction of concrete and reinforcement. Conclusions. According to the results of the comparison of the two approaches, conclusions are drawn about the advantages and disadvantages of the methods. Advantages of nonlinear dynamic calculation methods are noted compared to the equivalent-static ones. Use of the combined approach to the description of the shock wave front gives a reduction in time and allows us to describe the interaction of the wave with the structure with sufficient accuracy. The findings indicate the relevance of the study and provide an opportunity to move to more reasonable computational models.

scholarly journals Impact of the fire on the bearing capacity of the ordinary concrete used in reinforced concrete structures in Burundi. History and architecture

Vestnik MGSU ◽  
2021 ◽  
pp. 1567-1572
Author(s):  
Emmanuel Mikerego ◽  
Donatien Nduwimana
Keyword(s):  
Reinforced Concrete ◽  
Bearing Capacity ◽  
Negative Impact ◽  
Heating Temperature ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Ordinary Concrete ◽  
The Impact

Introduction. This paper presents the results of an assessment of the impact of fire on the bearing capacity of the ordinary concrete, to be taken into account in the rehabilitation of fire-damaged reinforced concrete structures in Burundi. Materials and methods. Experimental samples of the ordinary concrete made respectively of coarse river aggregates and crushed coarse quarry aggregates were prepared and subjected to different heating temperatures (250, 350, 450, 600 and 900 °C) simulating the fire. After natural cooling, experimental samples were subjected to compression test; and diagrams showing the loss of the load-bearing capacity of the ordinary concrete used in reinforced concrete structures in Burundi were drawn. Results. Negative impact of the fire on the load-bearing capacity of the ordinary concrete occurs above of 350 °C of heating temperature. Concrete made of crushed coarse quarry aggregates loses 50 and 78 % of its bearing capacity at around 525 and 900 °C of heating temperature, respectively. Similarly, concrete made of coarse river aggregates loses 50 and 70 % of its load-bearing capacity respectively at 600 and 900 °C of heating temperature. An evaluation curve of the after-fire bea­ring capacity of the concrete used in reinforced concrete structures in Burundi is established. Conclusions. The negative impact of the fire on the load-bearing capacity of the ordinary concrete occurs above of 350 °C of heating temperature. Concretes made of crushed coarse quarry aggregates and concrete made of coarse river aggregates lose 50 % of its bearing capacity at around 525 and 600 °C of heating temperature respectively. Knowing the heating temperature that the fire-damaged reinforced concrete structure has undergone is indispensable in deciding on its demolition or rehabilitation.

A Practical Investigation into Acoustic Wave Propagation in Concrete Structures

2006 ◽  
Vol 13-14 ◽  
pp. 205-212 ◽  
Author(s):  
Muhamad Bunnori Norazura ◽  
Rhys Pullin ◽  
Karen M. Holford ◽  
R.J. Lark
Keyword(s):  
Wave Propagation ◽  
Reinforced Concrete ◽  
Wave Velocity ◽  
Concrete Slab ◽  
Concrete Structures ◽  
Reinforced Concrete Beam ◽  
Health Condition ◽  
Time Of Arrival ◽  
Reinforced Concrete Slab ◽  
Single Wave

Acoustic Emission (AE) testing in concrete structures shows great potential for monitoring and assessing the health condition of structures. Source location is normally based on the arrival times of transient signals, the simplest method is known as the Time of Arrival (TOA) method, where the location of the damage can be determined from the arrival time of the event at two or more sensors. When using this method, the wave velocity of the signals that propagate through the material needs to be determined. Homogenous materials, such as steel, have welldefined velocities, but in non-homogeneous materials such as concrete the wave velocity is more difficult to predict. This makes the use of a single wave velocity as required in the TOA method very difficult due to the variety of wave velocities obtained, especially for large structures. This paper explores wave propagation in concrete structures over a variety of source to sensor distances. Experiments were performed on a reinforced concrete beam and a reinforced concrete slab, using an Hsu-Nelsen (H-N) Source. It is found that, in general, as the source to sensor distance increases, the wave velocity decreases. The presence of longitudinal and transverse waves is demonstrated and the influence of the part of the waveform used for temporal measurement is explored. In order to provide a practical approach to velocity determination, different thresholds are investigated and the results are discussed in relation to the wave modes present.

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