scholarly journals Structural Behavior of Large-Scale I-Beams with Combined Textile and CFRP Reinforcement

2020 ◽  
Vol 10 (13) ◽  
pp. 4625 ◽  
Author(s):  
Jan Bielak ◽  
Maximilian Schmidt ◽  
Josef Hegger ◽  
Frank Jesse
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Large Scale ◽  
Concrete Strength ◽  
Limit State ◽  
Shear Capacity ◽  
Flexural Behavior ◽  
Ultimate Limit State ◽  
Full Potential ◽  
Line Load

With the innovative composite material carbon-reinforced concrete, thin-walled, high-performance components can be realized. A combination of carbon fiber reinforced polymer (CFRP) bars and non-metallic textile grids is advantageous as it exploits the full potential of the high-performance materials to reduce dead loads, increases durability, and extends lifespan. For new components with such mixed reinforcement, applicable design concepts and engineering rules are necessary to accurately determine the structural and deformation behavior. To validate models and detailing rules previously developed, three large carbon reinforced concrete I-beams were designed and tested to failure with a realistic line load. CFRP bars served as principal bending reinforcement, whereas shear and flange reinforcement consisted of textile grids. Results showed that existing models for bending using variation of strain distribution as well as non-linear finite-element analysis predicted the flexural behavior of structural components with mixed reinforcement in ultimate limit state (ULS) appropriately. Yet, calculation of shear capacity requires further studies to determine textile reinforcement contribution and estimate reduction for concrete strength in reinforced compression struts. For serviceability limit state (SLS), three methods for determination of deflection delivered good results. In future, a rethinking is required with regard to the ductility and robustness of CFRP-reinforced concrete components. In this respect, pronounced cracking as well as the large ultimate strain and deflection compensate for the lacking yield capacity of the reinforcement.

scholarly journals Flexural and Shear Tests on Reinforced Concrete Bridge Deck Slab Segments with a Textile-Reinforced Concrete Strengthening Layer

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4210 ◽  
Author(s):  
Viviane Adam ◽  
Jan Bielak ◽  
Christian Dommes ◽  
Norbert Will ◽  
Josef Hegger
Keyword(s):  
Reinforced Concrete ◽  
High Performance ◽  
Large Scale ◽  
Shear Failure ◽  
Bridge Deck ◽  
High Strength ◽  
Shear Capacity ◽  
Strengthening Effect ◽  
Textile Reinforced Concrete ◽  
Carbon Fibre Reinforced Polymer

Many older bridges feature capacity deficiencies. This is mainly due to changes in code provisions which came along with stricter design rules and increasing traffic, leading to higher loads on the structure. To address capacity deficiencies of bridges, refined structural analyses with more detailed design approaches can be applied. If bridge assessment does not provide sufficient capacity, strengthening can be a pertinent solution to extend the bridge’s service lifetime. For numerous cases, applying an extra layer of textile-reinforced concrete (TRC) can be a convenient method to achieve the required resistance. Here, carbon fibre-reinforced polymer reinforcement together with a high-performance mortar was used within the scope of developing a strengthening layer for bridge deck slabs, called SMART-DECK. Due to the high tensile strength of the carbon and its resistance to corrosion, a thin layer with high strength and low additional dead load can be realised. While the strengthening effect of TRC for slabs under flexural loading has already been investigated several times, the presented test programme also covered increase in shear capacity, which is the other crucial failure mode to be considered in design. A total of 14 large-scale tests on TRC-strengthened slab segments were tested under static and cyclic loading. The experimental study revealed high increases in capacity for both bending and shear failure.

Combined Reinforced Concrete Columns Strengthening with Steel Clipping and Concrete Surfacing

2021 ◽  
pp. 11-22
Author(s):  
Ю. Г. Москалькова ◽  
С. В. Данилов ◽  
В. А. Ржевуцкая
Keyword(s):  
Reinforced Concrete ◽  
Load Transfer ◽  
Limit State ◽  
Concrete Columns ◽  
Ultimate Limit State ◽  
Concrete Core ◽  
Reinforced Concrete Columns ◽  
Entire Height ◽  
Complex Structural ◽  
Ultimate Limit

Постановка задачи. Исследуется метод усиления железобетонных колонн устройством стальной обоймы с обетонированием, который позволяет восстанавливать эксплуатационные показатели колонн, имеющих значительные дефекты и повреждения. Предпосылкой настоящих исследований явилось предположение о том, что усиление стальной обоймой с обетонированием является эффективным способом повышения несущей способности железобетонных колонн, причем вариант приложения нагрузки - только на бетонное ядро или ко всему сечению - существенно на эффективность усиления не влияет. В связи с этим целью исследования является определение необходимости устройства стального оголовка и включения в работу ветвей стальной обоймы при условии обетонирования стержня колонны по всей высоте. Результаты и выводы. Рациональным признан способ передачи нагрузки только на бетонное ядро усиленных колонн, поскольку устройство оголовка стальной обоймы требует применения сложных конструктивно-технологических решений, но при этом дополнительно увеличивает несущую способность незначительно (согласно проведенным исследованиям менее чем на 10 %). Ввиду отсутствия необходимости устройства конструкций стального оголовка снижаются трудоемкость и сроки производства работ по усилению колонн. Statement of the problem. The method of strengthening reinforced concrete columns with a steel clipping and the concrete surfacing is investigated. This method allows one to repair the columns with significant defects and damage. The prerequisite for this study was the assumption of strengthening with a steel clipping and the concrete surfacing is an effective way to increase the ultimate limit state of reinforced concrete columns, furthermore, the option of applying the load (only to the concrete core or to the entire section) does not significantly affect the strengthening effectiveness. In this regard, the purpose of the investigation was to identify the need to include the steel jacketing in the work, on the condition the column is coated with concrete along with the entire height. Results and conclusions. The load transfer method only to the concrete core of the strengthened columns is recognized as rational since the device of the steel clipping head requires the use of complex structural and technological solutions, but at the same time additionally increases the ultimate limit state insignificantly (according to the studies by less than 10 %). Due to the absence of the need to establish structures of the steel jacketing head, the labor intensiveness and terms of work production on strengthening the columns are reduced.

Application potential of textile reinforcement in concrete construction for infrastructure buildings: environmental performance and availability

2021 ◽  
Author(s):  
Sara Reichenbach ◽  
Benjamin Kromoser ◽  
Philipp Preinstorfer ◽  
Tobias Huber
Keyword(s):  
High Performance ◽  
Construction Material ◽  
Limit State ◽  
Carbon Dioxide Emission ◽  
Resource Consumption ◽  
Ultimate Limit State ◽  
Textile Reinforced Concrete ◽  
Potential Applications ◽  
Application Potential ◽  
Ultimate Limit

<p>With the building industry being one of the main sources of carbon dioxide emission worldwide and concrete being the main construction material, new strategies have to be developed to reduce the carbon footprint thereof. The use of high-performance materials in structural concrete, as for example textile-reinforced concrete (TRC), seems to allow for a reduction of the resource consumption and the carbon emissions. The present paper addresses potential applications of TRC examining the global warming potential (GWP) of a rail platform barrier. The resource consumption is depicted in a parametrical study in terms of the necessary component height and reinforcement area considering both the serviceability limit state (SLS) as well as the ultimate limit state (ULS). The results clearly indicate an achievable reduction of the GWP during construction when using textile reinforcement made of high-performance fibres. Furthermore, an analysis of the European market was conducted to prove the availability of this new reinforcement type. </p>

Permafrost Thawing-Pipeline Interaction Advanced Finite Element Model

2009 ◽  
Author(s):  
Jianfeng Xu ◽  
Basel Abdalla ◽  
Ayman Eltaher ◽  
Paul Jukes
Keyword(s):  
Finite Element ◽  
Energy Demand ◽  
Large Scale ◽  
Limit State ◽  
The Arctic ◽  
Ultimate Limit State ◽  
Fe Model ◽  
Field Development ◽  
Thaw Settlement ◽  
Permafrost Thawing

The increasing energy demand has promoted the interest in exploration and field development in the Arctic waters, which holds one quarter of the world’s petroleum reserves. The harsh conditions and fragile environment in the arctic region introduce many challenges to a sustainable development of these resources. One of the key challenges is the engineering consideration of warm pipelines installed in permafrost areas; found mainly in shallow waters and shore crossings. Evaluations have to be made during the pipeline design to avoid significant thaw settlement and large-scale permafrost degrading. In this paper, a three-dimensional (3D) finite element (FE) model was developed to study the interaction between buried pipelines transporting warm hydrocarbons and the surrounding permafrost. This interaction is a combination of several mechanisms: heat transfer from the pipeline, results in permafrost thawing and formation of thaw bulb around the pipeline. Consequently, the thaw settlement of soil beneath the pipeline base results in bending strains in the pipe wall. For safe operations, the pipe should be designed so that the induced strains do not exceed the ultimate limit state conditions. The developed model helps in accurate prediction of pipe strains by using finite element continuum modeling method as opposed to the more commonly used discrete (springs) modeling and hand calculations. It also assesses the real size of the thaw bulb and the corresponding settlement at any time, thus preventing an over-conservative design.

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 Design of reinforced concrete beams with steel fibers in the ultimate limit state

2018 ◽  
Vol 11 (5) ◽  
pp. 997-1024
Author(s):  
T. E. T. BUTTIGNOL ◽  
J. F. FERNANDES ◽  
T. N. BITTENCOURT ◽  
J. L. A. O. SOUSA
Keyword(s):  
Reinforced Concrete ◽  
Concrete Beams ◽  
Limit State ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Experimental Results ◽  
Reinforced Concrete Beams ◽  
Ultimate Limit State ◽  
Bending Tests

Abstract This paper carries out a design analysis of reinforced concrete beams with steel fibers following the fib Model Code 2010 (MC 2010) procedures. The values obtained from the design calculations are compared with the experimental results of reinforced concrete beams with 20kg/m3 and 60 kg/m3 of steel fibers submitted to four-point bending tests. In the first part, the procedures for the classification and characterization of the material are explained. The experimental results of three-point bending tests performed on notched steel fiber reinforced concrete (FRC) beams following EN 14651 procedures are described. Moreover, the characterization of the FRC beams according to MC 2010, are carried out. In the second part, the flexural design of reinforced concrete beams with steel fibers, according to MC 2010, is carried out. A sectional analysis is performed in order to obtain the moment-curvature and the force-vertical displacement curves. The theoretical values are compared with the experimental results. Besides, a linear statistic analysis by means of the Rule of Mixture is carried out in order to analyze the variation of the flexural capacity of the reinforced beams with different amounts of steel fibers. The results demonstrated that the design rules described in the MC 2010 are on the safe side. The flexural resistance of concretes with different amounts of fiber incorporation can be determined by the Rule of Mixture, which has shown a high correlation factor (R2) with the experimental values.

scholarly journals Flexural Behavior of Precast Concrete Segmental Box-Girders with Dry Joints

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Shun Chai ◽  
Tong Guo ◽  
Zheheng Chen ◽  
Jun Yang
Keyword(s):  
Large Scale ◽  
Precast Concrete ◽  
Concrete Strength ◽  
Flexural Behavior ◽  
Box Girders ◽  
Flexural Performance ◽  
External Tendons ◽  
Flexural Bearing Capacity ◽  
Tendon Force ◽  
Concrete Strain

Precast concrete segmental (PCS) box-girders are widely used in bridge construction, while studies on flexural behaviors of PSC box-girders with dry joints are insufficient. Six large-scale PCS box-girders with dry joints were tested to failure under two-point loading in this study. Strain increments, tendon forces, deflections at mid-span, and cracks were recorded during the tests. Multiple factors were investigated with regards to their influence on flexural performance of girders. It is found that most specimens failed due to the excessive force in tendons, while the specimen with external tendons failed due to concrete compressive crushing. Larger shear span ratio resulted in greater increase in tendon force and concrete strain during loading and, accordingly, the lowest ultimate flexural capacity. Lower concrete strength resulted in larger increase in concrete strain and tendon force during loading and relatively smaller deflection at failure. For the specimen with four segments, a significant increase in tendon force and smaller deflections at failure was observed as compared with specimen 1, though the failure load was similar. Numerical simulation is further conducted, where it is found that the area of prestressed tendon and the number of joints have a significant influence on ultimate flexural bearing capacity and deflection; besides, deflection control standard of PCS girders should be stricter than that of the integral cast girder. The corbel joints, in general, show better ultimate performance than the castle-shaped joints.

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