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1
Constantinos Β. Demakos, Constantinos C. Repapis, Dimitrios P. Drivas i Panagiotis Kaoukis. "Experimental investigation of FRP strengthened reinforced concrete T-beams in torsion". Global Journal of Engineering and Technology Advances 16, nr 1 (30.07.2023): 050–57. http://dx.doi.org/10.30574/gjeta.2023.16.1.0130.
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In general, reinforced concrete (RC) members are most commonly influenced by flexural moments, axial and shear forces. However, they may also be subject to torsional moments. Torsion in reinforced concrete (RC) beams is an important phenomenon that affects the structural behaviour of buildings. Both the concrete and steel reinforcement contribute to the torsional resistance of a RC member. However, the contribution of concrete is usually neglected by the modern design codes, due to cracking. Moreover, the subject of maintenance and repair or strengthening of existing RC structures is a significant problem. The last years, fibre reinforced polymer (FRP) is widely used as external reinforcement in flexural and shear strengthening. Nevertheless, its use in torsional strengthening is not so widely investigated. Ιn this paper, the torsional behaviour of RC T-beams reinforced in shear with FRPs is experimentally investigated. Five groups of T-beams subject to pure torsion, two of which are control beams and other three beams are strengthened in shear with U-jacketed FRP fabrics. Experimental results reveal that FRPs can increase the ultimate torsional capacity of the member.
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Kagermanov, Alexander, i Paola Ceresa. "3D Fiber-Based Frame Element with Multiaxial Stress Interaction for RC Structures". Advances in Civil Engineering 2018 (15.08.2018): 1–13. http://dx.doi.org/10.1155/2018/8596970.
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A three-dimensional fiber-based frame element accounting for multiaxial stress conditions in reinforced concrete structures is presented. The element formulation relies on the classical Timoshenko beam theory combined with sectional fiber discretization and a triaxial constitutive model for reinforced concrete consisting of an orthotropic, smeared crack material model based on the fixed crack assumption. Torsional effects are included through the Saint-Venant theory of torsion, which accounts for out-of-plane displacements perpendicular to the cross section due to warping effects. The formulation was implemented into a force-based beam-column element and verified against monotonic and cyclic tests of reinforced concrete columns in biaxial bending, beams in combined flexure-torsion, and flexure-torsion-shear.
3
Hu, Shao Wei, i Ke Yu Zhao. "Experimental Research on Torsional Performance of Prestressed Composite Box Beam with Partial Shear Connection". Applied Mechanics and Materials 438-439 (październik 2013): 658–62. http://dx.doi.org/10.4028/www.scientific.net/amm.438-439.658.
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In order to research torsional performance of prestressed steel-concrete composite box beam with different shear connection, this paper designed three prestressed steel-concrete composite box beams with different degree of shear connection, and studied the stress characteristics of prestressed composite beam under static torsion process load. The torsion behaviors of prestressed composite beam such as the steel strain, concrete flange strain, rebar strain, angle of torsion, deformation and failure patterns are analyzed on the base of the experimental results. It comes to a result that shear connectors have little impact on beams cracking torque, but ultimate torque of composite beams decreases along with the reduction of shear connection degree. When the shear connection degree is 0.5, the ultimate torque is reduced by about 15%.
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Lyublinskiy, Valery, i Vladislav Struchkov. "Torsion RC structures of asymmetric multistory buildings". E3S Web of Conferences 410 (2023): 02017. http://dx.doi.org/10.1051/e3sconf/202341002017.
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In multi-storey buildings that are asymmetrical in plan, an eccentricity occurs between the center of mass and the center of stiffness. Under the action of wind and seismic horizontal loads, torsion appears in the bearing system of the building. Torsion can also occur in nominally symmetrical buildings caused by uneven deformations of structural components. There are numerous analytical and experimental studies of the effect of torsion on bearing structures. It is required to assess the achievement of the ultimate states of reinforced concrete structures and shear bonds that create a spatial system. This paper uses computer simulation to study the stress-strain state of the welded bond under the action of shear and torque. Two joint models are considered, which are subject to only shear and shear with torsion. The results show the process of destruction of the joint, deformation of the shear walls to be joined, and a decrease in the rigidity of the connection. The study is useful for understanding the mechanisms of twisting effects during translational and rotational vibrations of a building.
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Raiyani, S. D., D. D. Joshi, P. V. Patel i S. R. Ramani. "Numerical study on Role of Shear Key in Precast Beam to Beam Connection Subjected to Torsion". Proceedings of the 12th Structural Engineering Convention, SEC 2022: Themes 1-2 1, nr 1 (19.12.2022): 57–61. http://dx.doi.org/10.38208/acp.v1.473.
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Connections play an important role in behaviour of precast concrete structures. It is also observed that the failure of precast building took place because of connection failure. Generally connection between precast elements are designed for axial force, shear force and bending moment. But when the precast beam supports precast slab of different span on both the side, torsional moment cannot be neglected. Therefore, it is important to study the behaviour of precast connections under the effect of pure torsional loading. In this paper effectiveness of shear key on behaviour of precast beam to beam connection under pure torsion is presented. A numerical simulation is carried out to investigate the torsional behaviour of three different type of precast wet connections with and without shear key using Finite Element Method based software ABAQUS. Projected longitudinal reinforcement of precast beam elements are welded after their erection and the gap is filled with concrete. The damaged plasticity model is employed for modelling the behaviour of concrete and elastic perfectly plastic models are employed for the modelling of behaviour of steel reinforcement. A prefect bond is assumed between the steel reinforcement and concrete. The damage along cracks, are modelled through concrete damage parameters. Precast beam connection with out shear key is considered as control beam. While other beam to beam connections have shear key of different configuration. Torque v/s twist behaviour and damage patterns as obtained from numerical analysis of different precast beam connections with shear key are compared with control specimen. Analysis results exhibited enhanced torsional strength of precast beam connection with shear key in comparison of connection without shear key.
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Ju, Hyunjin, i Alina Serik. "Torsional Strength of Recycled Coarse Aggregate Reinforced Concrete Beams". CivilEng 4, nr 1 (16.01.2023): 55–64. http://dx.doi.org/10.3390/civileng4010004.
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This study discusses the torsional capacity of recycled coarse aggregate (RCA) reinforced concrete beams under pure torsion based on the experimental findings available in the literature. The experimental data on RCA specimens were collected and compared with the conventional concrete specimens with key variables, such as compressive strength and longitudinal and transverse reinforcement ratios, as those variables affect the torsional capacity of reinforced concrete beams. Overall, the database consisted of experimental results from 30 RCA specimens and 256 natural coarse aggregate (NCA) specimens. The result shows that specimens with a 100 % replacement ratio have the lowest strength. In addition, as the structural mechanism of torsion is similar to the shear mechanism in reinforced concrete beams, a comparative analysis was performed with RCA specimens subjected to shear force. It was concluded that the RCA has a similar effect in strength reduction for the specimens subjected to torsion or shear with a 100% replacement ratio. However, further study and experimental evidence are required to confirm the applicability of the recycled aggregate to produce and design the structural members.
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Yu, Zhigang, i Deshan Shan. "Experimental and numerical studies of T-shaped reinforced concrete members subjected to combined compression-bending-shear-torsion". Advances in Structural Engineering 24, nr 12 (17.05.2021): 2809–25. http://dx.doi.org/10.1177/13694332211012577.
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The study of reinforced concrete members subjected to combined loads always has been an important research topic in the field of engineering, but the torsional behavior of T-shaped reinforced concrete members subjected to combined loads has yet to be determined. This paper is focused on providing a detailed explanation of the torsional behavior of T-shaped reinforced concrete members subjected to combined compression-bending-shear-torsion. From the perspective of experimental tests and numerical analyses, in this paper, we discuss the effects of combined loads on the torsion bearing capacity, the development of cracks and the failure mode, strains of key points in the concrete and longitudinal reinforcement, and the relation of torsion and angular displacement. We conducted experiments and numerical analyses of four groups of reinforced concrete members by using the main variables of the axial pressure ratio and the bending moment. Also, the experimental and calculated results are compared based on the elastic-plastic damage constitutive model of concrete. Based on the test data and the existing formula, we also extended the formula used to calculate the torsion bearing capacity and provided diagrams of the interaction when combined loads were applied. In addition, the results of this study highlight the turning point from torsion failure to compression-bending-torsion failure. The test results demonstrated that torsion capability increases in the specified range of axial pressure ratio and decreases as bending increases. The test results also indicate the importance of considering the effects of compression-shear-bending on the torsion bearing capacity in the engineering design.
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Bayrak, Barış. "The Behavior of Hybrid Fiber RC Shear Walls Subjected to Monolithic Pure Torsion: An Analytical Study". Civil Engineering Beyond Limits 3, nr 3 (16.11.2022): 1–7. http://dx.doi.org/10.36937/cebel.2022.1745.
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The reinforced concrete (RC) shear walls are widely used to serve as the primary lateral load-resisting member in the high-rise buildings. An experimental investigation and analysis of the mechanical behaviour of hybrid fiber reinforced self-compacting concrete (HFRSCC) shear walls under pure torsion moment is presented in this paper. The nine HFSCC shear walls with the same height and longitudinal reinforcement ratio analytically were tested under pure torsion moment and no axial load. The effect of hybrid fiber ratio and horizontal reinforcement amount and aspect ratio on the failure characteristics, torsional behaviour, energy dissipation capacity of squat shear walls was studied. Result indicate that both hybrid and horizontal reinforcement ratio are increased the maximum torsional moment capacity and twist angle and that the hybrid fiber ratio is the key parameter that determines the failure mode of the HFSCC shear walls.
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Men, Jin Jie, Qing Xuan Shi i Qiu Wei Wang. "Unity Equation of Torsional Capacity for RC Members Subjected to Axial Compression, Bend, Shear and Torque". Advanced Materials Research 163-167 (grudzień 2010): 874–79. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.874.
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The mechanics performance of reinforced concrete members subjected to axial compression, bending, shear and torque is very complex. Several calculation models have been established to estimate the torsional capacity of combined torsion members; however, the calculation results of different models have a great variation. In this paper, variable-angle space truss model is adopted to analyze the mechanics performance of reinforced concrete members subjected to combined torsion. With respect to various shapes of specimens, various load modes, and various strength of concrete, a unity equation about torsional capacity of combined torsional member is obtained. Based on the unity equation, the torsional capacity of 59 combined torsional specimens is calculated. In contrast with the equation of ACI and the code of China, the torsional capacity calculated by the unity equation agrees well with the results of experiment and much better than the results of ACI code and China code. It is concluded that the unity equation can provide valuable reference for calculation and design of combined torsion members.
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Mavaddat, Shahbaz, i M. Saeed Mirza. "Computer analysis of thin-walled concrete box beams". Canadian Journal of Civil Engineering 16, nr 6 (1.12.1989): 902–9. http://dx.doi.org/10.1139/l89-133.
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Three computer programs, written in FORTRAN WATFIV, are developed to analyze straight, monolithically cast, symmetric concrete box beams with one, two, or three cells and side cantilevers over a simple span or over two spans with symmetric mid-span loadings. The analysis, based on Maisel's formulation, is performed in three stages. First, the structure is idealized as a beam and the normal and shear stresses are calculated using the simple bending theory and St-Venant's theory of torsion. The secondary stresses arising from torsional and distortional warping and shear lag are calculated in the second and third stages, respectively. The execution times on an AMDAHL 580 system are 0.02, 0.93, and 0.25 s for the three programs, respectively. The stresses arising in each stage of analysis are then superposed to determine the overall response of the box section to the applied loading. The results are compared with Maisel's hand calculations. Key words: bending, bimoment, box beam, computer analysis, FORTRAN, shear, shear lag, thin-walled section, torsion, torsional and distortional warping.
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KOLCHUNOV, VL I. "DEPLANATION HYPOTHESES FOR ANGULAR DEFORMATIONS IN REINFORCED CONCRETE STRUCTURES UNDER COMBINED TORSION AND BENDING". Building and reconstruction 100, nr 2 (2022): 3–12. http://dx.doi.org/10.33979/2073-7416-2022-100-2-3-12.
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The article analyzes the hypothesis of deplanation of angular deformations in reinforced concrete structures during bending with torsion. A simple method from the field of the grid methods for approximating the deformations of complex functions under the 3D stress state is considered. Diagrams of angular and linear deformations in such structures were built and analyzed to find these deformations, bending and torques perceived by the concrete of the compressed area using the accepted hypotheses and coefficients for projecting normal and shear stresses (strains) through diagrams of compressed concrete and working reinforcement. Approximating the calculated section by small squares, a spatial surface of deformations was constructed. This is with the corresponding gradients of these deformations in the section with a crack, and on this basis, expressions were written for the total longitudinal deformations in the section and shear deformations in the section of the element during bending with torsion. Using the membrane analogy of the Timoshenko-Goodyear stress functions and the proposed version of new complex functions from the field of the grid method, an analysis was made of its error, when we find the value of complex functions at the considered characteristic points (2%) and at any points of the cross section (7%). The use of the proposed hypotheses and the given version of complex functions makes it possible considering the warping of the 3D stressed section of a reinforced concrete element with cracks undergoing bending with torsion.
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Rahal, Khaldoun N. "Torsional strength of reinforced concrete beams". Canadian Journal of Civil Engineering 27, nr 3 (1.06.2000): 445–53. http://dx.doi.org/10.1139/l99-083.
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A simple method for predicting the ultimate strength and mode of failure of reinforced concrete beams subjected to pure torsion is presented. This method is an extension of a recently developed method for predicting the strength of membrane elements subjected to pure shear that was also applied to beams subjected to combined shearing forces, bending moments, and axial loads. The torsional strength is related to the amounts of transverse and longitudinal reinforcement and to the concrete strength. To check the adequacy of this simple method, the calculated strength and mode of failure are checked against the experimental results of 66 beam tests available in the literature, and good agreement is found. The simplicity of the method is illustrated by an example.Key words: beams, building codes, mode of failure, reinforced concrete, shear, strength, torsion.
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Haroon, Muhammad, Seungbum Koo, DongIk Shin i Changhyuk Kim. "Torsional Behavior Evaluation of Reinforced Concrete Beams Using Artificial Neural Network". Applied Sciences 11, nr 10 (14.05.2021): 4465. http://dx.doi.org/10.3390/app11104465.
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Artificial neural networks (ANNs) are an emerging field of research and have proven to have significant potential for use in structural engineering. In previous literature, many studies successfully utilized ANNs to analyze the structures under different loading conditions and verified the accuracy of the approach. Several studies investigated the use of ANNs to analyze the shear behavior of reinforced concrete (RC) members. However, few studies have focused on the potential use of an ANN for analysis of the torsional behavior of an RC member. Torsion is a complex problem and modeling the torsional fracture mechanism using the traditional analytical approach is problematic. Recent studies show that the nonlinear behavior of RC members under torsion can be modeled using ANNs. This paper presents a comprehensive analytical and parametric study of the torsional response of RC beams using ANNs. The ANN model was trained and validated against an experimental database of 159 RC beams reported in the literature. The results were compared with the predictions of design codes. The results show that ANNs can effectively model the torsional behavior of RC beams. The parametric study presented in this paper provides greater insight into the torsional resistance mechanism of RC beams and its characteristic parameters.
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Qiao, Peng, Jin Di i Feng-jiang Qin. "Warping Torsional and Distortional Stress of Composited Box Girder with Corrugated Steel Webs". Mathematical Problems in Engineering 2018 (2018): 1–13. http://dx.doi.org/10.1155/2018/7613231.
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The torsional behaviors of composite box girders with corrugated steel webs are more obvious than traditional concrete girders due to the lower torsional rigidity. In this paper, the torsion and distortion of this kind of composite girder are studied. The formulas for warping normal stress and shear stress were put forward according to the second theory of Umanskii, considering the accordion effect of corrugated steel webs. Then, the influences of different dimensional parameters on the torsional and distortional stress are investigated. Results show that the effect of parameters on stress is different and implicit in composite box girders with corrugated steel webs. Under eccentric loads, the warping torsional and distortional stress in this kind of girder should not be neglected. Compared with girders under corresponding symmetric loads, the total warping stress may be as big as flexural normal stress, and the total shear stress usually reaches 30 to 50 percentage of flexural shear stress. So the warping stress and additional shear stress due to warping torsion and distortion are suggested to be calculated by the proposed equations in structural analysis, which are usually not taken into account in conventional concrete box girders.
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Mohammed, Alyaa H., Kaiss F. Sarsam i Qais A. Hasan. "The Influence of Shear Strain on the Torsion Capacity of Hybrid Beams". Engineering and Technology Journal 38, nr 7A (25.07.2020): 951–59. http://dx.doi.org/10.30684/etj.v38i7a.371.
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This research discusses experimentally the shear strain of the reinforcement concrete hybrid beams composed of reactive powder concrete (RPC) at the peripheral and conventional concrete (CC) at the core beams under torsional strength tests. Shear strain is usually represented by (), which is explained as the tangent of the angle and is be like the length of deformation at its maximum divided by the length of perpendicular in the plane of the force application. Twelve reinforced concrete beams are tested having the following dimensions: 100, 200 and 1500mm as width, height and length respectively with thickness of the RPC concrete were 40 and 20mm. The beams were cast and tested to failure in torsion by using two opposite cantilevers steel arms that contribute to transferring the torque to the centre of the beams. Two control (CC and RPC) beams were poured, and the ten other beams were all poured as hybrid ones. Experimental data of the three strain gauges locations in the middle of the beams in one of the side surface face, to calculate shear strain (). The percentage of shear strain at ultimate torsion capacity was reduced by about 76% for RPC (RP) to CC (NC) beams and 63% for hybrid beam (H1) to CC (NC) beam.
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Saleh, Samoel M., Fareed H. Majeed, Osamah Al-Salih i Haleem K. Hussain. "Torsional Behavior of Steel-Concrete-Steel Sandwich Beams with Welded Stirrups as Shear Connectors". Civil Engineering Journal 9, nr 1 (1.01.2023): 208–19. http://dx.doi.org/10.28991/cej-2023-09-01-016.
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The structural performance of a steel-concrete-steel sandwich beam (SCSSB) with welded stirrups to the steel skin plates as shear connections exposed to a pure torsion load was studied in this paper. Eight SCSSB specimens were fabricated and tested under pure torsion. The effects of the compressive strength of the concrete core, 26 and 35 MPa, the thickness of the top and bottom steel skin plates, 2 and 4 mm, and the degree of shear interaction, which represents the number of beam stirrups, between the steel skin plates and the concrete core are 75, 100, and 125%. The experiment beams revealed a similar mode of failure for all SCSSB specimens regarding all considered variables, which started with inclined cracks along the specimens’ side faces and ended with local separation between one of the steel skin plates (top or bottom) and the concrete core. In addition, the experiment results showed an increase in the torsional strength with the increase in the shear connection ratio and the thickness of the steel skin plate, as well as with the increase in the strength of the concrete core. However, it was observed that the torsional ductility of the tested beams is proportional directly to the steel skin plate thickness and degree of interaction and inversely with the concrete compressive strength. The results showed that the use of steel skin plates with welded stirrups as a shear connection could reduce the negative effect of increasing the compressive strength of the concrete core on the torsional ductility of SCSSB. Doi: 10.28991/CEJ-2023-09-01-016 Full Text: PDF
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Křístek, Vladimír, Jaroslav Průša i Jan L. Vítek. "Torsion of Reinforced Concrete Structural Members". Solid State Phenomena 272 (luty 2018): 178–84. http://dx.doi.org/10.4028/www.scientific.net/ssp.272.178.
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According to the common design methods of calculation of the stress state induced by torsion of massive prismatic concrete structural elements, the structural system is reduced to a simple cage consisting of ties and struts. This model has, however, a number of principal shortcomings, the major of them is the fact that all of simultaneously acting effects like axial forces, bending moments and shear forces are not taken into account – the compressive axial forces increase very significantly the torque capacity of structural members, while due to action of tensile forces, bending moments and shear forces the torque capacity is reduced. These phenomena, applying non-linear approaches, are analysed and assessed.
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Barros, R., i J. S. Giongo. "Shear force and torsion in reinforced concrete beam elements: theoretical analysis based on Brazilian Standard Code ABNT NBR 6118:2007". Revista IBRACON de Estruturas e Materiais 5, nr 5 (październik 2012): 576–95. http://dx.doi.org/10.1590/s1983-41952012000500002.
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Reinforced concrete beam elements are submitted to applicable loads along their life cycle that cause shear and torsion. These elements may be subject to only shear, pure torsion or both, torsion and shear combined. The Brazilian Standard Code ABNT NBR 6118:2007 [1] fixes conditions to calculate the transverse reinforcement area in beam reinforced concrete elements, using two design models, based on the strut and tie analogy model, first studied by Mörsch [2]. The strut angle θ (theta) can be considered constant and equal to 45º (Model I), or varying between 30º and 45º (Model II). In the case of transversal ties (stirrups), the variation of angle α (alpha) is between 45º and 90º. When the equilibrium torsion is required, a resistant model based on space truss with hollow section is considered. The space truss admits an inclination angle θ between 30º and 45º, in accordance with beam elements subjected to shear. This paper presents a theoretical study of models I and II for combined shear and torsion, in which ranges the geometry and intensity of action in reinforced concrete beams, aimed to verify the consumption of transverse reinforcement in accordance with the calculation model adopted As the strut angle on model II ranges from 30º to 45º, transverse reinforcement area (Asw) decreases, and total reinforcement area, which includes longitudinal torsion reinforcement (Asℓ), increases. It appears that, when considering model II with strut angle above 40º, under shear only, transverse reinforcement area increases 22% compared to values obtained using model I.
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Gong, Yongzhi, Faxing Ding, Liping Wang, Borong Huang, Yingjie Shan i Fei Lyu. "Finite Model Analysis and Practical Design Equations of Circular Concrete-Filled Steel Tube Columns Subjected to Compression-Torsion Load". Materials 14, nr 19 (25.09.2021): 5564. http://dx.doi.org/10.3390/ma14195564.
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The objective of this study is to investigate the mechanical properties and the composite action of circular concrete-filled steel tube (CFST) columns subjected to compression-torsion load using finite element model analysis. Load–strain (T–γ) curves, normal stress, shear stress, and the composite action between the steel tubes and the interior concrete were analyzed based on the verified 3D finite element models. The results indicate that with the increase of axial force, the maximum shear stress at the core concrete increased significantly, and the maximum shear stress of the steel tubes gradually decreased. Meanwhile, the torsional bearing capacity of the column increased at first and then decreased. The torque share in the columns changed from the tube-sharing domain to the concrete-sharing domain, while the axial force of the steel tube remained unchanged. Practical design equations for the torsional capacity of axially loaded circular CFST columns were proposed based on the parametric analysis. The accuracy and validity of the proposed equations were verified against the collected experimental results.
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Makhdoumi, Hamed, Seyyed Hesam Madani, Mehdi Shahraki, Mostafa Khodarahmi i Naser Nosratzehi. "Comparison and Evaluation of Retrofitting Different Modes of Concrete Structures by FRP". Advanced Materials Research 1129 (listopad 2015): 242–48. http://dx.doi.org/10.4028/www.scientific.net/amr.1129.242.
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Abstract. After recent earthquakes in the majority of seismic areas around the world including our country Iran and considering the irretrievable casualties and economic lost due to these earthquakes, natural catastrophic mitigation committees, research and scientific centers that are responsible for providing structural and seismic codes presented the concept of performance design, study of lifelines and retrofit and rehabilitation of existing and vital structures and the majority of researches in the field of earthquake engineering and structural engineering is focused on retrofit of structures considering economic and feasibility problems. Considering the increasing use of concrete structures in Iran and their substituting for steel structures ( due to weaknesses, constructional problems and defects) and considering the internal defects and failure modes, these structures should be retrofitted against earthquakes or preparations should be provided to decrease and minimize failure modes. concrete frames that consist of beam, column and connection is a essential part of concrete structures. Internal defect of concrete frame results in failure modes such as debonding and delamination in beams, buckling and torsion in column, local crashing in connection. Considering the several benefits of FRP sheets and their increasing use during years, these composites can be used for compressive-tensile, shear, bending, torsional retrofitting as well as for ductility increasing. In this study different types of failure modes of concrete frames and internal defects of them that lead to collapse are investigated. In addition different cases of retrofitting by FRP sheets to prevent failure modes and exciting defect are presented and these cases are compared.
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Hsu, Thomas T. C. "Shear Flow Zone in Torsion of Reinforced Concrete". Journal of Structural Engineering 116, nr 11 (listopad 1990): 3206–26. http://dx.doi.org/10.1061/(asce)0733-9445(1990)116:11(3206).
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Budzyński, Waldemar. "Proposition of a new method for the calculation of diagonal crack widths in reinforced concrete elements subjected to combined torsion and shear". Budownictwo i Architektura 2, nr 1 (11.06.2008): 037–64. http://dx.doi.org/10.35784/bud-arch.2311.
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This paper concerns the phenomenon of cracking in reinforced concrete elements subjected to combined torsion and shear. The theoretical model developed by Rahal and Collins is described in de tail. This model is the only one which is capable of predicting the full response (e.g.: steel and concrete strains, deformations, curvatures) rectangular reinforced concrete sections subjected to combined torsion and shear throughout their post cracking loading history. The assumptions of Modified Compression Field Theory are also described because the model of Rahal and Collins is based on this theory. It also contains a concept of the new method which is capable of determining the width of cracks in reinforced concrete elements subjected to combined torque moment and shear force. The method is based on the model suggested by Rahal and Collins.
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Merkulov, S., S. Esipov i S. Kashuba. "PRELIMINARY DESCRIPTION OF THE WORK OF REINFORCED CONCRETE ELEMENTS WITH EXTERNAL REINFORCEMENT WITH COMPOSITE MATERIALS DURING BENDING WITH TORSION". Bulletin of Belgorod State Technological University named after. V. G. Shukhov 7, nr 11 (26.07.2022): 40–48. http://dx.doi.org/10.34031/2071-7318-2022-7-11-40-48.
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The calculation methods of reinforced external reinforcement elements when working on torsion are considered succinctly in available sources and current regulatory documents. This article discusses a number of existing proven methods for calculating reinforced concrete bendable elements with external composite reinforcement, including when working with torsion. The necessity of introducing into the existing calculation dependences of the prerequisites for substantiating the behavior of reinforced concrete bendable elements, including those with external composite reinforcement, when working in a complex stress-strain state is described. The cases of occurrence of additional torsional forces in the conditions of classical variants of loads and impacts on the element are considered. A description of the work of reinforced concrete elements with external reinforcement with composite materials during bending with torsion is proposed. The main provisions of the work of reinforced concrete structures in bending with torsion are given. The main limiting states are presented. An assumptions are made about the possible presence of additional limiting states of reinforced concrete elements with external reinforcement with composite materials. A variant of the condition of proportionality of longitudinal relative deformations for reinforced concrete elements with external reinforcement with composite materials during bending with torsion is proposed.
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Zhu, Yingbo, Shui Wan, Kongjian Shen, Qiang Su i Xiayuan Li. "Modified rotating-angle softened truss model for composite box-girder with corrugated steel webs under pure torsion". Advances in Structural Engineering 23, nr 9 (6.02.2020): 1902–21. http://dx.doi.org/10.1177/1369433219898063.
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Replacement of traditional concrete webs with corrugated steel webs will lead to a significant decrease in torsional stiffness of composite box-girder with corrugated steel webs, which needs special attention in the design of wide and curved composite box-girder with corrugated steel webs. To improve the accuracy of prediction on the entire torsional performance of composite box-girder with corrugated steel webs, a modified rotating-angle softened truss model for torsion is developed in this study. Modified rotating-angle softened truss model for torsion mainly takes into account the new three-stage average stress coefficients, the new two-stage shear strain relationship between corrugated steel web and slabs, and the torsional deformation coordination of whole cross section. To testify the accuracy of modified rotating-angle softened truss model for torsion and to better understand the performance of composite box-girder with corrugated steel webs under pure torsion, two scaled specimens are tested in this article. The torque–twist curves and shear strains calculated by modified rotating-angle softened truss model for torsion reach a good agreement with experimental results, which indicates that modified rotating-angle softened truss model for torsion can successfully predict the entire torsional performance of composite box-girder with corrugated steel webs. In addition, compared with test data obtained from previous literature, the proposed modified rotating-angle softened truss model for torsion is more capable of predicting full torsional response of composite box-girder with corrugated steel webs than other rotating-angle models, especially at cracking stage and ultimate stage.
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Mohaisen, Saad Khalaf, Ali Adel Abdulhameed i Majid Mohammad Kharnoob. "Behavior of Reinforced Concrete Continuous Beams under Pure Torsion". Journal of Engineering 22, nr 12 (1.12.2016): 1–15. http://dx.doi.org/10.31026/j.eng.2016.12.01.
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Practically, torsion is normally combined with flexure and shear actions. Even though, the behavior of reinforced concrete continuous beams under pure torsion is investigated in this study. It was performed on four RC continuous beams under pure torsion. In order to produce torsional moment on the external supports, an eccentric load was applied at various distances from the longitudinal axis of the RC beams until failure.
Variables considered in this study are absolute vertical displacement of the external supports, torsional moment’s capacity, angle of twist and first cracks occurrences. According to experimental results; when load eccentricity increased from 30cm to 60cm, the absolute vertical displacement increased about 46.92% and the angle of twist increased about 45.76% at failure. It has been also found that the ultimate failure loads decreased about 49.65% when the load eccentricity increased from 30cm to 60cm. Furthermore, the first crack was monitored and it was found that the first crack occurred at higher stages of loading with low loading eccentricity. The first crack records appeared at 75.86%, 70.80%, 63.16% and 54.79% of loading when the load eccentricities are 30, 40, 50 and 60cm, respectively.
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Zhu, Mingqiao, Zefeng Yan, Lin Chen, Zhongliang Lu i Y. Frank Chen. "Experimental study on composite mechanical properties of a double-deck prestressed concrete box girder". Advances in Structural Engineering 22, nr 12 (22.05.2019): 2545–56. http://dx.doi.org/10.1177/1369433219845150.
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A series of tests were carried out on a scaled (1:8) double-deck prestressed concrete box girder in this study, aiming to study the structural response and failure mechanism of the box girder under prestressed axial compression, transverse bending, and torsion. The test results, such as the twist angle, crack development, and distortion of the box girder, were analyzed in detail. The results show that (1) the box girder eventually suffered lateral bending damage, and the cross-section of the support distorted severely; (2) torsional cracking occurred in the pure torsion region at the mid-span, but the longitudinal and transverse rebars did not yield, indicating that the pure torsion section of the box girder was still in the early stage of torsion failure; and (3) after the cracking of the box girder, stress redistribution phenomenon occurred, resulting in obvious nonlinear strain variations. Comparison of the longitudinal and transverse steel strains showed that transverse steel withstood the most shear stress during the early stage of torsion.
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Xu, Xun, i Shi Zhong Qiang. "The New Analytical Theory of Restrained Torsion of Thick-Walled Concrete Box Girder Bridge". Applied Mechanics and Materials 188 (czerwiec 2012): 168–76. http://dx.doi.org/10.4028/www.scientific.net/amm.188.168.
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Directed toward the feature of restrained torsion of concrete box girder bridge, the layered approach of analyzing restrained torsion is put forward, displacement model and geometric equation are established by using the generalized coordinates principle, and the formula of restrained torsion shear stress is derived, and then a analytical theory of restrained torsion of thick-walled box girder is established based on the mixed variational principle. The numerical experiment indicate that it cannot be neglected that thick-walled effect of restrained torsion of concrete box girder bridge and the predicted results by the new theory are accurate.
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Kolchunov, Vladimir, i Sergey Bulkin. "CALCULATION SCHEME OF REINFORCED CONCRETE STRUCTURES OF CIRCULAR CROSS-SECTION UNDER BENDING WITH TORSION". International Journal for Computational Civil and Structural Engineering 17, nr 3 (29.09.2021): 63–82. http://dx.doi.org/10.22337/2587-9618-2021-17-3-63-82.
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The developed design diagram of the ultimate resistance of reinforced concrete structures in bending with torsion of circular cross-sections most fully reflects the features of their actual exploitation. For a spatial crack of a diagonal large ellipse, sections are taken in the form of a swirling propeller with concave and convex spatial parabolas from the first and second blocks between vertical transverse circular sections from the beginning to the end of the crack. For practical calculations in compressed and tensioned concrete, a polyline section of three sections is considered: two longitudinal trapezoids and the third middle section of the radius curve of a small ellipse close to forty-five degrees. When calculating unknown forces, solutions of the equations of equilibrium and deformations of the sections are made up to the end of the crack passing through the moment points for the resultant moments and the projections of internal and external forces. Shear torsional stresses along the linear longitudinal sections of the trapezoid were presented, as well as normal and shear stresses located on the end cross-sections at a distance x from the support. The height of the compressed area of concrete decreases with an increase in bending moments in the spatial section between the first and third cross-sections. It is found in their relationships and connections. The dowel action of reinforcement is determined using a special model of the second level with discrete constants. The static loading scheme was considered from the standpoint of an additional proportional relationship between the torques along the length of the bar in the spatial section and the first and third transverse sections. For a dangerous spatial crack, when projected onto the horizontal axis, the length C was found from a diagonal large ellipse of a round bar.
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J. De-la-Colina i J. Valdés. "Eccentric force excitation of a reinforced concrete building to assess torsion amplification". Electronic Journal of Structural Engineering 11 (1.01.2011): 1–10. http://dx.doi.org/10.56748/ejse.11138.
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Dynamic analysis should be preferred for seismic design of buildings and other structures instead of a static one. However, in several current building codes seismic static design of buildings requires an amplification of torsion moments (or story eccentricities) computed from lateral forces statically applied at floor levels. Discrepancy of factors used to estimate torsion amplification among codes suggests further study on this subject. The main objective of this paper is to show estimations of the building dynamic torsion. These estimations were obtained from experiments conducted in a four-story reinforced concrete building without accidental eccentricity that was excited with a dynamic force generator placed at the roof. The exciter was operated at several frequencies and it was placed at two roof positions. By assuming three degrees of freedom for each building slab and using acceleration records from tests, equations of motion of the system were used to estimate dynamic story torsional moments. Results support the idea that building torsional response also depends on coupling between the excitation force frequency and the building modal frequencies associated with torsion (either pure torsion or translation coupled with torsion).
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Behera, Gopal Charan, Tippabhotla Durga Gunneswara Rao i Chittem Butchi Kameswara. "Study of Post-Cracking Torsional Behaviour of High-Strength Reinforced Concrete Beams with a Ferrocement Wrap". Slovak Journal of Civil Engineering 22, nr 3 (1.09.2014): 1–12. http://dx.doi.org/10.2478/sjce-2014-0012.
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Abstract The post-cracking behaviour of structures subjected to torsion can be well predicted by Hsu’s softened truss model. The softened truss model is applicable to structures having symmetry in their material properties on all four sides. Wrapping on three faces is a common phenomenon when the top face is provided with a flange or slab. Such a wrapping on three faces of a beam is referred to as a “U” wrap. “U” wraps are better wrapping strategies for distressed structures, as their top face is not accessible for many structures. The material property of an unwrapped face differs from the rest of wrapped faces. For the effective use of wrapping, the unwrapped face needs to be provided with a material having a higher resistance to tension and shear. For this, high-strength concrete in the core is a better option. Here, an attempt is made to predict the torsional capacity of “U” wrapped high-strength concrete beams having an asymmetry in the material using a softened truss model with suitable modifications of the material properties. Efficient algorithms are proposed for the solution of simultaneous equations. The predictions are found to be in good agreement with the experimental test results
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Xu, Jianchao, Bo Diao, Quanquan Guo, Yinghua Ye, Y. L. Mo i Tianmin Zhou. "Parametric Study on Mixed Torsional Behavior of U-Shaped Thin-Walled RC Girders". Advances in Civil Engineering 2018 (15.11.2018): 1–18. http://dx.doi.org/10.1155/2018/3497390.
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Nowadays, U-shaped thin-walled concrete girders have been widely applied in the urban construction of rail viaducts in China as well as worldwide. However, the mixed torsional behaviors of these structures are not well understood. In this paper, the mixed torsional behaviors of the U-shaped thin-walled RC girders are theoretically analyzed, and a method predicting failure modes and ultimate torques is proposed. Nonlinear FE models based on ABAQUS to simulate the mixed torsional behaviors are built and calibrated with the test results. Parametric studies considering three crucial parameters (boundary condition, span length-section height ratio, and ratio of longitudinal bars to stirrups) are conducted based on both the above suggested calculating method and the FE modeling. The calculated and the simulated results agree well with each other and with the test results. It is found that the failure modes of the U-shaped thin-walled RC girders under torsion are influenced by all the three parameters. Three kinds of failure modes are observed: flexural failures dominated by warping moment, shear failures caused by warping torque and circulatory torque, and flexural-shear failures in the cases where flexural failure and shear failure appear almost at the same time.
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Zhang, Yan Ling, Wei Ge i De Ying Zhang. "Experimental Research on Bending-Torsion Characteristics of Steel-Concrete Composite Box Beams". Advanced Materials Research 594-597 (listopad 2012): 785–90. http://dx.doi.org/10.4028/www.scientific.net/amr.594-597.785.
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Due to the axial curvature and the eccentric vehicle loads, bending-torsion couple effects will be generated in the curved steel-concrete composite box beam bridges. To study the bending-torsion couple characteristics, six steel-concrete composite box model beams are tested under the bending-torsion couple loads, with the initial torsion-bending ratios and shear connection degrees as the design parameters. The ultimate bearing capacity, section strain, and interfacial slip of the steel-concrete composite box beams are measured. The test results show that, the fully connected composite beams mainly express bending or bending-torsion failure modes, but the partially connected composite beams are mainly sliding failure modes. The existence of the torque doesn’t have great influence on the ultimate bearing capacity and bending moment of the composite box beams. Under the bending-torsion couple loads, there are not only the longitudinal slip between the steel girder and concrete slab of the composite box beam, but also the transverse slip perpendicular to the beam axis.
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Thivya, J., R. Malathy i D. Tensing. "A Comparative Study of Ultimate Strength and Behaviour of Steel Concrete Composite Beam with Shear Connectors Subjected to Pure Torsion". Journal of Computational and Theoretical Nanoscience 13, nr 10 (1.10.2016): 6892–95. http://dx.doi.org/10.1166/jctn.2016.5643.
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This study concerns the employment of pure torsion analysis to determine ultimate strength of composite beam with shear connectors. The effect of shear connector is used for increasing the strength and stiffness of composite beam. This behavior is influenced by physical response of the beam under pure torsion. Totally 12 beams are tested and comparative analysis has been made within this 12 beams. The curvature, rotation and angle of twist are calculated throughout entire load by torsion test. This investigation proves that the composite beam with 75 mm spaced shear connector provides good ultimate strength.
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Sabah, Hadeel A. H., i Ibrahim S. I. Harba. "A Review-Behavior of Reinforced Concrete Exterior Beam-Column Connections under Cyclic Loading". E3S Web of Conferences 318 (2021): 03008. http://dx.doi.org/10.1051/e3sconf/202131803008.
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In many seismically active regions worldwide, massive reinforced concrete (RC) structures built before the 1970s existed. These older RC buildings, in countries having seismic history, were designed for gravity loads only. Anyway, the beam-column connections influence the structures where the functions of connection shortage by transport the forces like shear, moment, and torsion through the beam to the column. Also, it could behave in a ductile manner to help the structure resist the seismic, as simulate the seismic loading by high and low cyclic loading. Due to the failure of external joints more than the internal beam-column joints, this review focuses on the behavior of exterior beam-column joints under cyclic loading, consequently simulated the behavior under an earthquake and the reinforcement detailed.
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Al-Nuaimi, A. S., i P. Bhatt. "2D Idealisation of Hollow Reinforced Concrete Beams Subjected to Combined Torsion, Bending and Shear". Journal of Engineering Research [TJER] 2, nr 1 (1.12.2005): 53. http://dx.doi.org/10.24200/tjer.vol2iss1pp53-68.
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This paper presents a finite element model for idealisation of reinforced concrete hollow beams using 2D plane elements. The method of ensuring compatibility between the plates using two-dimensional model to analyze this type of structures is discussed. Cross-sectional distortion was minimised by incorporating end diaphragms in the FE model. Experimental results from eight reinforced concrete hollow beams are compared with the non-linear predictions produced by a 2D in-house FE program. The beam dimensions were 300x300 mm cross section with 200x200 mm hollow core and 3800 mm long. The beam ends were filled with concrete to form solid end diaphragms to prevent local distortion. The beams were subjected to combined bending, torsion and shear. It was found that the two-dimensional idealisation of hollow beams is adequate provided that compatibility of displacements between adjoining plates along the line of intersection is maintained and the cross-sectional distortion is reduced to minimum. The results from the 2D in-house finite element program showed a good agreement with experimental results.
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Ma, Sheng Qiang, Norazura Muhamad Bunnori i Kok Keong Choong. "Experimental Study on Reinforced Concrete Box Beam Strengthened by CFRP under Combined Action". Applied Mechanics and Materials 802 (październik 2015): 184–89. http://dx.doi.org/10.4028/www.scientific.net/amm.802.184.
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An experimental investigation was presented in this paper on reinforced concrete box beams subjected to shear, torsion, and bending moment strengthened by carbon fiber reinforced polymer (CFRP). Eight box beams were cast and separated into two groups according to two different torque-to-shear and torque-to-bending moment ratios. Three box beams from each group strengthened by CFRP in different configurations and one control box beam were tested. The main parameters of this experiment were the different ratios and configurations, including U-jacket layers and U-jacket strips with or without longitudinal strips. The cracking and failure mode, effect of wrapping configuration, torsional capacity, and behavior of the different torque-to-shear and torque-to-bending moment ratios were studied in the paper.
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Kwon, Minho, P. Benson Shing, Chip Mallare i Jose Restrepo. "Seismic Resistance of RC Bent Caps in Elevated Mass Transit Structures". Earthquake Spectra 27, nr 1 (luty 2011): 67–88. http://dx.doi.org/10.1193/1.3533471.
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This paper presents a study of the seismic resistance of two reinforced concrete cap beams in existing elevated guideway structures constructed in the 1960s. One beam has a regular configuration and the other has an irregular configuration. For each beam type, a half-scale model was designed, constructed, and tested. The irregular beam tested had a larger depth and a higher quantity of main longitudinal steel. While the regular beam had spiral confinement extending into the beam-to-column joint, the irregular beam did not. The beams were subjected to simultaneous bending, shear, and torsion in the tests, with the torsion induced by the vertical eccentricity of the horizontal load exerted at the top face of the beams. The test results underscore the importance of confinement steel in the beam-to- column joint of a cap beam and the critical role of the longitudinal reinforcement in the beams for torsional resistance. A numerical parametric study has been conducted with nonlinear finite element and strut-and-tie models, which have been validated with the experimental results. The study has indicated that the seismic load resistance of a cap beam can decrease with a reduced gravity load, which is an important consideration for design.
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Joh, Changbin, Imjong Kwahk, Jungwoo Lee, In-Hwan Yang i Byung-Suk Kim. "Torsional Behavior of High-Strength Concrete Beams with Minimum Reinforcement Ratio". Advances in Civil Engineering 2019 (17.01.2019): 1–11. http://dx.doi.org/10.1155/2019/1432697.
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Although there is a growing trend to use higher strength for concrete and steel in reinforced concrete structures due to the lightness and slenderness of these members together with the simplified arrangement of their reinforcement, there is still the necessity to inspect the reduction of ductility resulting from the gain in strength. Taking into account that this also concerns the design for torsion, this study intends to investigate the regulations related to the torsional minimum reinforcement ratio in view of the minimum ductility requirement with focus on Eurocode 2. To that goal, the relation between the torsional cracking moment and the ductile behavior is discussed for the beam reinforced with the minimum torsional reinforcement ratio to examine the eventual properness of the minimum torsional reinforcement ratio recommended by Eurocode 2. Moreover, a pure torsion test is performed on 18 beams made of 80 MPa concrete reinforced by high-strength bars with rectangular section and various test variables involving the minimum torsional reinforcement ratio, the transverse-to-longitudinal reinforcement ratio, and the total reinforcement ratio. As a result, for the high-strength concrete beams, the minimum torsional reinforcement ratio recommended by Eurocode 2 was insufficient to prevent the sudden loss of strength after the initiation of the torsional cracking. But with regard to the compatibility torsion of statically indeterminate structure, the adoption of the minimum torsional reinforcement ratio recommended by Eurocode 2 might secure enough deformability under displacement-controlled mode to allow the redistribution of the torsional moment.
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ANDRADE, R. C. de, i T. N. BITTENCOURT. "Concrete beam subjected to shear and torsion: a comparison between the Brazilian Standard Code NBR 6118, ACI and AASHTO Provisions". Revista IBRACON de Estruturas e Materiais 13, nr 1 (luty 2020): 160–70. http://dx.doi.org/10.1590/s1983-41952020000100011.
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Abstract Most of torsion studies available are relative to pure torsion, arising from the exclusive application of a torsion moment in a concrete beam. This situation, however, is only possible in laboratories. In practice, the vast majority of twisted beams are subjected to the combination of shear forces and torsion, which gives rise to a more complex state of stress to be analyzed. The purpose of this paper is to present the provisions of the ACI 318/2014 Codes, AASHTO and ABNT NBR 6118: 2014 related to shear and torsion, and compare some results with experimental data from Rahal & Collins[3]. It is shown that if the recommended value of 45º is used for θ, the ACI 318/2014 provisions for shear-torsion interaction give similar results compared to ABNT NBR6118: 2014, but these results are very conservative. If the lower limit of 30º is used, the results obtained using both codes departs, and less consistent results are obtained. This paper concludes that using the recommended value of 36º obtained with the AASHTO provisions, some consistent and more accurate results are obtained.
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O'Regan, Chris. "Technical Guidance Note Level 2 No. 25: Designing for torsion in reinforced concrete elements". Structural Engineer 98, nr 4 (1.04.2020): 24–27. http://dx.doi.org/10.56330/pfui2722.
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Reinforced concrete elements have an inherent resistance to applied torque due to the geometry of their cross-section. Nevertheless, the resulting stress due to applied torque is additive to other actions, such as bending moments, and axial and shear forces. This Technical Guidance Note discusses the impact torsion has on the design and detailing of reinforced concrete elements. It should be read in conjunction with Level 1, No. 21 How to avoid torsion.
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Alnuaimi, A. S. "Comparison between Experimental and 3D Finite Element Analysis of Reinforced and Partially Pre-Stressed Concrete Solid Beams Subjected to Combined Load of Bending, Torsion and Shear". Journal of Engineering Research [TJER] 5, nr 1 (1.12.2008): 79. http://dx.doi.org/10.24200/tjer.vol5iss1pp79-96.
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This paper presents a non-linear analysis of three reinforced and two partially prestressed concrete solid beams based on a 20 node isoparametric element using an in-house 3D finite element program. Anon linear elastic isotropic model, proposed by Kotsovos, was used to model concrete behaviour, while steel was modelled as an embedded element exhibiting elastic-perfectly plastic response. Allowance was made for shear retention and for tension stiffening in concrete after cracking. Only in a fixed direction, smeared cracking modelling was adopted. The beams dimensions were 300x300 mm cross section, 3800 mm length and were subjected to combined bending, torsion and shear. Experimental results were compared with the non-linear predictions. The comparison was judged by load displacement relationship, steel strain, angle of twist, failure load, crack pattern and mode of failure. Good agreement was observed between the predicted ultimate load and the experimentally measured loads. It was concluded that the present program can confidently be used to predict the behaviour and failure load of reinforced and partially prestressed concrete solid beams subjected to a combined load of bending, torsion and shear.
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Bamonte, Patrick, Pietro G. Gambarova, Nataša Kalaba i Sergio Tattoni. "Some considerations on shear and torsion in R/C structural members in fire". Journal of Structural Fire Engineering 9, nr 2 (11.06.2018): 94–107. http://dx.doi.org/10.1108/jsfe-01-2017-0019.
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Purpose This study aims to provide a factual justification of the extension to fire conditions of the well-known design models for the calculations of R/C members at the ultimate limit state in shear and torsion. Both solid and thin-walled sections are considered. In the latter case, the little-known topic of shear-transfer mechanisms at high temperature is introduced and discussed. Design/methodology/approach Both the effective-section method and the zone method are treated, as well as the strut-and-tie models required by the analysis of the so-called D zones (discontinuity zones), where heat-enhanced cracking further bears out the phenomenological basis of the models. Findings The increasing role played by the stirrups in shear and by the rather cold concrete core in torsion stand out clearly in fire, while high temperatures rapidly reduce the contributions of such resisting mechanisms as concrete-teeth bending, aggregate interlock and dowel action. Originality/value On the whole, beside quantifying the side contributions of web mechanisms and section core in fire conditions, this study indicates a possible approach to extend to fire the available models on the coupling of shear and bending, and shear and torsion in R/C members.
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Obel, William, Bernardo Horowitz i Luís F. A. Bernardo. "Analysis of RC Beams under Combined Torsion and Shear Using Optimization Techniques Evaluation of NBR 6118 and AASHTO LRFD Standards". Journal of Composites Science 6, nr 6 (15.06.2022): 175. http://dx.doi.org/10.3390/jcs6060175.
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In this article, a novel calculation procedure using optimization techniques is proposed to compute the torsion–shear interaction curves for reinforced concrete (RC) beams. The calculation procedure is applied to NBR 6118 and AASHTO LRFD standards in order to evaluate their reliability. For this, some experimental results found in the literature and related to RC beams tested under combined torsion and shear, as well as results from the combined-action softened truss Model (CA-STM), are used for comparison. From the obtained results, AASHTO LRFD provisions are found to –be satisfactorily accurate. The NBR 6118 provisions are found to be consistent with the experimental results when the angle of the concrete struts is assumed to be variable or equal to the lower bound value of 30°, according to model II of the standard. For an angle assumed equal to 45°, according to model I of the NBR 6118 standard, the predicted strengths are found to be excessively conservative. The results demonstrate that formulating the analysis of RC beams under combined torsion and shear as an optimization problem, as proposed in this article, constitutes an alternative and efficient option. In addition, the generality of the proposed calculation procedure allows it to be applied to any design standard to compute the torsion–shear interaction curves for RC beams.
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Kadlec, Lukáš, Václav Ráček, Vladimír Křístek i Jan L. Vítek. "Fibre-Concrete Tubes in Pure Shear Mode". Advanced Materials Research 1106 (czerwiec 2015): 144–47. http://dx.doi.org/10.4028/www.scientific.net/amr.1106.144.
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Fibre-concrete is rapidly developing material, which becomes more widely often used. Strong feature of fibre-concrete is its ability of carrying stress after reaching the ultimate strength. In order to fully understand this material it is necessary to observe its performance in different types of failure. The aim was to create experiment in which the conditions of pure torsion are realized without accompanying by other stress. During testing there will be observed not only the ultimate strength, but also the torque-twist diagram and stress variation on the descending post-peak curve. Experiment of this new character will give results of great importance and will contribute to full understanding of performance of material fibre-concrete.
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KOLCHUNOV, VL I., A. I. DEMYANOV i M. V. PROTCHENKO. "MOMENTS IN REINFORCED CONCRETE STRUCTURES UNDER BENDING WITH TORSION". Building and reconstruction 95, nr 3 (2021): 27–46. http://dx.doi.org/10.33979/2073-7416-2021-95-3-27-46.
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The moments in reinforced concrete during bending with torsion were determined, the new first hypothesis of linear deformations and its filling of the diagram during bending with torsion for the analytical second functional as a function of three functions - an exponent, a straight line and a parabola curve. A simple new method is found (from the family of mesh methods) and a summed function of additional deplanation is proposed. The new second hypothesis of angular deformations and its filling of the diagram in reinforced concrete during bending with torsion is constructed. The analytical first general undefined functional is a function of functions, as well as transitions, operations between functions. At the same time, a spatial triple integral of arguments from longitudinal deformations for the first hypothesis was obtained, as well as the third and fourth functionals (indefinite and definite) from moments (bending and twisting) with the projection of the coefficients of the diagram of "deformations - stresses" of compressed concrete and the filling coefficients of the diagrams of compressed concrete for their shoulders to the neutral axis for a field of small squares. The bending and torque moments from the compressed area of concrete and working reinforcement are determined (folded for their levels or expanded into algebraic functions from the synthesis of the computational model of reinforced concrete blocks). In this case, we have new functionals (from the first to the fourth functional), proposed hypotheses (first and second), as well as cross sections (from small squares) to a spatial crack. There are also jumps (cracks) lateral, normal, etc., from the first - third stage of average deformations of concrete and working reinforcement.
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Karpenko, Nikolay, Vladimir Kolchunov, Vitaly Kolchunov i Vladimir Travush. "CALCULATION MODEL OF A COMPLEX-STRESSED REINFORCED CONCRETE ELEMENT UNDER TORSION WITH BENDING". International Journal for Computational Civil and Structural Engineering 17, nr 1 (24.03.2021): 34–47. http://dx.doi.org/10.22337/2587-9618-2021-17-1-34-47.
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The article presents the methodology and principles of creating calculation models for reinforced concrete structures operating in conditions of complex resistance. A block calculation model of reinforced concrete bar structures in torsion with bending is presented. This model consists of a support block formed by a spatial crack and a compressed zone of concrete closed on it and a second block formed by a vertical section running perpendicular to the longitudinal axis of a reinforced concrete element along the edge of the compressed zone closing the spatial spiral. Cases are considered when the torque effec has the greatest influenceon the stress-strain state of structures. In this case, the following forces are taken into account as the calculated forces in the spatial section: normal and tangential forces in the concrete of the compressed zone; components of axial and shear forces in the reinforcement crossed by a spatial crack. A feature of the proposed calculation model is that it considers independently of each other the strength of an element in spatial sections passing along a spatial crack, and the strength of an element between spatial cracks. The spatial section is formed by a crack located on three sides of the element and a compressed zone located on the fourth side and closing the ends of the spiral crack. In this case, the compressed zone, depending on the ratio of the bending and torque moments, can be located along the horizontal and vertical (lateral) edges of the element. The governing equations are written in the form of static equations for the adopted calculation cross-sections and a closed-loop system that unites them, written as a function of many variables with Lagrange multipliers λi. On the basis of the constructed function for all the variables included in it, an additional non-decaying system of equations has been compiled, from which follows a dependence that allows finding the projecton of a dangerous spatial crack.
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Karpenko, N. I., Vl I. Kolchunov i V. I. Travush. "CALCULATION MODEL OF A COMPLEX STRESS REINFORCED CONCRETE ELEMENT OF A BOXED SECTION DURING TORSION WITH BENDING". Russian Journal of Building Construction and Architecture, nr 3(51) (21.07.2021): 7–26. http://dx.doi.org/10.36622/vstu.2021.51.3.001.
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Statement of the problem. Based on the analysis of domestic and foreign scientific publications and guidelines, it is found that the known deformation models for the calculation of complex tensile reinforced concrete elements during torsional bending are quite conditional. Therefore the article considers the solution of the problem of designing a computational model of a reinforced concrete element during torsion with bending in the post-crack stage, which most fully accounts for the specifics of crack formation, deformation and destruction of such elements. The case is considered for when among all possible external influences the action of torques and bending moments has the greatest influence on the stress-strain. Results. Using the equations of statics and physical ratios of reinforced concrete, the calculated parameters are identified such as stresses in concrete of compressed zone, height of compressed concrete, stresses in clamps, deformations in concrete and reinforcement, curvature and torsion angle of reinforced concrete element. Conclusions. The obtained analytical dependences were tested by means of numerical calculation of the reinforced concrete strapping crossbar of the outer contour of a residential building of box section of high-strength concrete. The suggested deformation model can be employed in the design of a wide class of reinforced concrete structures working on torsional bending.
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Travush, Vladimir I., Nikolay I. Karpenko, Vladimir I. Kolchunov, Semen S. Kaprielov, Alexey I. Demyanov, Sergei A. Bulkin i Violetta S. Moskovtseva. "Results of experimental studies of high-strength fiber reinforced concrete beams with round cross-sections under combined bending and torsion". Structural Mechanics of Engineering Constructions and Buildings 16, nr 4 (15.12.2020): 290–97. http://dx.doi.org/10.22363/1815-5235-2020-16-4-290-297.
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The aim of the work - experimental investigation on crack propagation and deformation in high-strength fiber reinforced concrete beams with round cross-sections under combined bending and torsion for the development of practical methods of crack resistance, deformation and strength analysis of such structures, and also for the accumulation of new experimental data on resistance under combined loading. Method is experimental-theoretical. Results. Deflection plots and force-deformation relationships for high-strength fiber reinforced concrete beams with round cross-sections under combined bending and torsion are determined experimentally. Principal deformations in terms of elongation and compression of concrete for the experimental beam structures with high torsion to bending moment ratio are determined. It is established that for high-strength fiber reinforced concrete structures of circular cross-section, generally, development of one-two discrete cracks is observed, therefore the circular shape of the cross-section slightly reduces the concentration defined by the material structure of high-strength concrete. On the basis of the conducted investigation on high-strength fiber reinforced concrete structures with circular sections, new experimental data on the combined stress-strain state in the studied areas of resistance is obtained, such as: values of generalized cracking, and failure, load, its level relative to the ultimate load; distance between the cracks at different stages of crack propagation; crack widths at principal reinforcement axis level, at a double diameter distance from the principal rebar axes and also along the entire crack profile at various stages of loading; coordinates of nonplanar crack formations; patterns of crack formation, development and opening in reinforced concrete structures under combined bending and torsion.
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NUNES, C. C. "Numerical analysis of torsional tangent rigidity of reinforced concrete waffle slab". Revista IBRACON de Estruturas e Materiais 12, nr 6 (grudzień 2019): 1454–67. http://dx.doi.org/10.1590/s1983-41952019000600013.
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Abstract This research work deals with the analysis of torsional tangent rigidity of reinforced concrete waffle slabs by comparisons of the numerical analysis with results of experimental tests, with calculations performed using the ATENA program. This program was specially developed for the calculation of reinforced concrete structures, considering the physical and geometric nonlinear analysis using the finite element method. Numerical analysis considered the tensile strength of the concrete and consequently the fracture energy. Numerical situations were tested to obtain the calibration of the numerical analysis with the laboratory tests. After the calibrations, the results were extrapolated to extreme situations to infer tangent torsion rigidity in new situations. It is concluded that, for waffle slabs, near the rupture, the torsional tangent rigidity should be 5% of the torsional tangent rigidity to the initial torsion. In service, considering one third of the total breaking load, the torsional tangent rigidity should be 85% of the torsional tangent rigidity to the initial twist. This great torsional tangent rigidity in service is another parameter that guarantees the structural efficiency of the waffle slabs and can be used in the most diverse applications of structural engineering.
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Xu, Deyi, Yang Yang i Zongping Chen. "Experimental Study and Damage Model on the Seismic Behavior of Reinforced Concrete L-Shaped Columns under Combined Torsion". Applied Sciences 10, nr 19 (8.10.2020): 7008. http://dx.doi.org/10.3390/app10197008.
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Due to the advantage of saving indoor space, a special-shaped column frame attracted more attention of the engineers and researchers. This paper presented a quasi-static cyclic loading experiment of six specimens of reinforced concrete (RC) L-shaped columns under compression-flexure-shear-torsion combined loadings to investigate the effect in the ratio of torsion to moment (T/M) and axial compression ratio (n) on their seismic performance. The results showed that the failure modes of L-shaped specimens included bending failure, bending-torsion failure, and torsion-shear failure with the hysteretic curves exhibiting S shape. With the increase of T/M ratio, cracks on the flange developed more fully, and the height of plastic hinge decreased and torsion bearing capacity improved. Besides, as the T/M ratio increased the twist ductility increased, while displacement ductility decreased. On the other hand, with a higher axial compression ratio, torsion bearing capacity and bending stiffness were both increased. Moreover, the equivalent viscous damping coefficient of bending and torsion were 0.08~0.28 and 0.13~0.23, respectively. The average inter-story drift ratio met the requirements of the Chinese standard. Finally, two modified models were proposed to predict the progression of damage for the L-shaped column under combined loading including torsion.