Modelling of a prestressed beam without concrete-to-steel bond (original) (raw)
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Comparison of Dynamic Characteristics of Prestressed and Reinforced Concrete Beams
Düzce Üniversitesi Bilim ve Teknoloji Dergisi, 2019
To determine the dynamic characteristics of bridges built with prestressed and reinforced concrete beams, the dynamic properties of such beams should be known. Prestressing force is applied to the prestressed concrete (PSC) beam, unlike reinforced concrete (RC) beam. In this study, it is aimed to compare the dynamic properties of PSC and RC beams with the same material, section properties and effective span length. Dynamic properties such as the mode shapes and periods of the PSC and RC beam were determined by means of the formulation found in the literature and a computer program that uses the finite element method. For this study I-beam with 0.90m height and 15m effective span length was selected as an example. The selected beam was considered separately as PSC and RC. In the PSC beam, eight low-relaxation Grade270 prestressing strand with 15mm (0.6 in.) diameter were used, unlike reinforced concrete beams. Three dimensional finite element models (FEM) of PSC and RC beam were cons...
Behavior of bonded and unbonded prestressed normal and high strength concrete beams
HBRC Journal, 2012
The major disadvantage of using ordinary reinforced concrete (RC) elements is the corrosion of steel, which occurs due to effect of cracks in tension zones. The main advantage of the fully prestressed concrete system is the absence of cracks in the concrete at the nominal service load and therefore better durability will be achieved. Combining the PC system with the use of high strength concrete is a milestone, which will potentially result in a new design approach. The disadvantage of the use of this combination is referred to the reduced ductility of concrete members. This paper presents an experimental program conducted to study the behavior of bonded and unbounded prestressed normal strength (NSC) and high strength concrete (HSC) beams. The program consists of a total of nine beams; two specimens were reinforced with non-prestressed reinforcement, four specimens were reinforced with bonded tendons, and the remaining three specimens were reinforced with unbonded tendons. The overall dimensions of the beams are 160 · 340 · 4400-mm. The beams were tested under cyclic loading up to failure to examine its flexural behavior. The main variables in this experimental program are nominal concrete compressive strength (43, 72 and 97 MPa), bonded and unbonded tendons and prestressing index (0%, 70% and 100%). Theoretical analysis using rational approach was also carried out to predict the flexural behavior of the specimens. Evaluation of the analytical work is introduced and compared to the results of the experimental work.
Materialwissenschaft und Werkstofftechnik, 2014
Firstly, the effect of traditional reinforcementprestressed reinforcement ratio on the behaviour of concrete beams up to failure was experimentally investigated. The beams were 10 m long and 0.5 m high, with different ratios of traditional and prestressed reinforcement. The total quantity of reinforcement in each beam was selected to provide their equal ultimate bending bearing capacity. Deflections, stresses in concrete, traditional and prestressed reinforcement, as well as concrete cracks, were monitored until the beams failure. Using the previously developed numerical model of authors of this paper for static analysis of spatial frame structures, which can simulate main nonlinear effects of their behaviour, then numerical analysis of tested beams was performed. Good agreement was obtained between the experimental and the numerical results, which confirms the possibility of practical application of the adopted numerical model. Main conclusions and recommendations for practical applications according to results of performed tests are given at the end.
Finite element analysis of the beam strengthened with prefabricated reinforced concrete plate
Scientific Research and Essays, 2010
Various strengthening methods were frequently carried out in the world to strengthen weaker cross section beams. In this study, one beam strengthened by bonding with a prefabricated plate which has 80 mm thickness underneath and one control beam were produced. The specimens were tested in the laboratory and a single load was applied on the middle of the beam. The results of the experiments were compared with the results obtained from the beam modelled with ANSYS finite element program. When the results of the experiments were compared with the modelled computer program, it was shown that the results of computer model gave similar results to the real behaviour.
D numerical modelling on prestressed concrete beams
This paper presents a model for the analysis of reinforced and prestressed concrete frame elements under combined loading conditions, including axial force, biaxial bending, torsion and biaxial shear force. The proposed model is based on the simple kinematic assumptions of the Timoshenko beam theory and holds for curved three dimensional frame elements with arbitrary cross-section geometry. The control sections of the frame element are subdivided into regions with 1D, 2D and 3D material response. The constitutive material model for reinforced and prestressed concrete follows the basic assumptions of the Modified Compression Field Theory with a tangent-stiffness formulation. The validity of the model is established by comparing its results with several well-known tests from the literature. These simulations include a variety of load combinations under bending, shear and torsion. The analytical results show excellent agreement with experimental data regarding the ultimate strength of the specimen and the local strain response from initiation of cracking to ultimate load.
Finite Element Analysis of Reinforced and pretensioned concrete beams
Concrete is strong in compression but weak in tension. Reinforced concrete, in which steel rods are provided to resist tensile stresses, however, does not meet the satisfactory structural demands. The concept of prestressing was introduced to generate compressive stresses in concrete prior to loading, by means of prestressing tendons inserted in the member. These compressive stresses resist the tensile forces, thereby effectively increasing the tensile strength of the concrete member. In this study, reinforced and pre-tensioned concrete beams are analysed for their nonlinear behaviour under external loading using the finite element method of analysis. ANSYS 12.0, an efficient finite element software package, is used for the analysis of the concrete members. Load-deflection responses, variations of stresses in concrete and steel and the crack patterns at critical stages of loading are studied. The numerical predictions are compared to the data obtained using the theories of structural analysis. In comparison to the theoretically predicted data, the numerical method of analysis using ANSYS was seen to satisfactorily predict the behavioural responses of the beams up to ultimate, but was not as effective in predicting the strain variation in the prestressing tendons.
Concrete is strong in compression but weak in tension. Reinforced concrete, in which steel rods are provided to resist tensile stresses, however, does not meet the satisfactory structural demands. The concept of prestressing was introduced to generate compressive stresses in concrete prior to loading, by means of prestressing tendons inserted in the member. These compressive stresses resist the tensile forces, thereby effectively increasing the tensile strength of the concrete member. In this study, reinforced and pre-tensioned concrete beams are analysed for their nonlinear behaviour under external loading using the finite element method of analysis. ANSYS 12.0, an efficient finite element software package, is used for the analysis of the concrete members. Load-deflection responses, variations of stresses in concrete and steel and the crack patterns at critical stages of loading are studied. The numerical predictions are compared to the data obtained using the theories of structural analysis. In comparison to the theoretically predicted data, the numerical method of analysis using ANSYS was seen to satisfactorily predict the behavioural responses of the beams up to ultimate, but was not as effective in predicting the strain variation in the prestressing tendons.
2011
An analytical method that determines the short and long-term response of prestressed and non-prestressed concrete beamcolumns reinforced with any combination of FRP bars or/and plates, steel rebars, bonded and/or unbonded prestressed tendons is proposed. Beams and columns encased with FRP fabrics and FRP tubes filled with concrete are covered with the proposed model. The effects of tension stiffening, creep and shrinkage of the concrete, and the relaxation of the prestressed steel reinforcement are considered. The models proposed by Vecchio and Collins [1] and by Popovics [2, 3] for the stress-strain relationships of the concrete in tension and compression are adopted, respectively. The strain-stress relationships of the steel and FRP reinforcements are modeled using multiple straight lines (polygonal lines). The method of the fibers (modified) is used to calculate the moment-curvature diagrams at different levels of the applied axial load (i.e., the M-P-f curves), and the Gauss method of integration (for the sum of the contributions of the fibers parallel to the neutral axis) to calculate the lateral rotations and deflections along the span of the beam-column. The validity of the proposed model and corresponding equations were tested against experimental data available in the technical literature (see part II of this publication).
Iranica Journal of Energy & Environment, 2013
Reinforcement and strengthening of reinforced concrete beams by unbounded external reinforcement is one of the methods of fortification used after loading and prior to failure of the beams. This method is used in different forms to strengthen members of reinforced concrete structures. To investigate the effect of fortification on cracked reinforced concrete beams, numbers of reinforced concrete beams were selected for testing. Strengthening was examined by attaching external reinforcing bars on both sides of the beams, at the level of internal flexural tensile reinforcement and by means of deflectors. The investigation was carried out through experimental data analysis and modeling using ANSYS finite element structural software. The results showed that the method of fortification used has increased the flexural capacity of the beams. It was also concluded that this method is suitable for strengthening of beams under their dead loads.
Analysis of Beam-Column Joint in a Pre-stressed Concrete Structure using Finite Element Method
International Journal for Research in Applied Science and Engineering Technology
Pre-stressed concrete is the type of concrete in which internal stresses of a suitable magnitude and distribution are induced so that the stresses resulting from external loads are counteracted to a desired degree. Pre-stressed concrete structures exhibit high strength and durability. These types of structures are very popular in use in bridge deck systems and culverts. However, various elements of pre-stressed concrete member undergo different types of stresses. The weakest element of these being beam column joint. The beam column joint in pre-stressed concrete member undergoes direct compression as well as bending compression and tension. This peculiarity of the beam column joint makes it vulnerable to failure. It was found that many authors studied the analysis of pre-stressed concrete structures using Finite Element Analysis. However, they have not included the beam column joint in their analysis. Hence, this study emphasized on this aspect of analysis of prestressed concrete structures. This paper presents the review of literature on 'Analysis of Beam Column Joint of a Pre-stressed Concrete Structure Using Finite Element Analysis'. It is been also observed from the existing literatures that Finite Element Method (FEM) is widely used for analysis of Pre-stressed Concrete Structures. The FEM is capable of incorporating complex boundary conditions and material non-linearity. The results of FEM are also comparable with that of hand calculations. Also the structure can be finely idealized using FEM which enhances accuracy of analysis. This will economize the structural sizes of Pre-stressed Concrete Element. The literature also indicates that the various researchers have used ANSYS, MIDAS and Stadd-Pro for the analysis of Prestressed Concrete Structures using FEM. This was an important observation and hence the present study aims to use ANSYS for the analysis of Beam Column joint using FEM. The present study aims at reviewing various research efforts undertaken by authors in the past. The study also aims at finding a gap in literature on analysis of beam column joint in a pre-stressed concrete member using Finite Element Analysis.