SHORT-TERM DEFORMATIONAL ANALYSIS OF PRESTRESSED CONCRETE BEAMS USING FLEXURAL CONSTITUTIVE MODEL (original) (raw)
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Journal of Civil Engineering and Management, 2005
In this paper, an attempt has been made to extend application of the recently proposed Flexural constitutive model to short-and long-term deformational analysis of flexural partially prestressed concrete members. The effect of tension stiffening and non-linear time effects of creep and shrinkage are taken into account. Effective modulus method is used for modelling long-term deformations. The proposed calculation technique is based on the layered approach and use of material stress-strain relationships. Curvatures prediction results were tested against experimental data of partially prestressed concrete beams reported in literature.
Numerical Study of the Flexural Behaviour of Precast Prestressed High Strength Concrete Beams
presents a finite element model developed to study the flexural behaviour of precast prestressed HSC beams using the commercial software 'Abaqus'. The material behaviour was simulated with: i) a plastic damage model for concrete; and ii) an elastic-plastic model for reinforcement with perfect bonding. The numerical model was validated by means of experimental results, being observed a good agreement.
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.
Simulation of Flexural Behavior of Damaged Prestressed Concrete Beam by Finite Element Method
Finite element model is applied to simulate the flexural behavior of bonded post tension prestressed concrete (PC) T beam. Flexural behavior of PC beam is characterized by load-deformation relationship in both linear elastic uncrack and nonlinear after cracking stage. Finite element analysis software, ANSYS, is utilized the simulation of flexural behaviors both loading and unloading path. Nonlinearity of materials are considered and taken into account. The developed model is verified by experimental results. The study finds good agreement between analytical and experimental results. Degradation of PC girder due to overload beyond cracking can be expressed by the loss of flexural stiffness and permanent deformation after unloading due to accumulated cracks. The verified finite element model (FEM) can be parametrically used to predict flexural behavior of PC beam in various levels of overloading.
Ultimate flexural strength of prestressed concrete beams: validation and model error evaluation
Revista IBRACON de Estruturas e Materiais, 2018
In this work a computational model is presented to evaluate the ultimate bending moment capacity of the cross section of reinforced and prestressed concrete beams. The computational routines follow the requirements of NBR 6118: 2014. This model is validated by comparing the results obtained with forty-one experimental tests found in the international bibliography. It is shown that the model is very simple, fast and reaches results very close to the experimental ones, with percentage difference of the order of 5%. This tool proved to be a great ally in the structural analysis of reinforced and prestressed concrete elements, besides it is a simplified alternative to obtain the cross section ultimate bending moment.
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.
Analysis of Behavior of Prestressed Concrete Structures Subjected to Torsion and Flexion
Reinforced concrete members subjected to simultaneous action of the bending moment, shear force and the torsional moment are not sufficiently investigated. Influence of the torsional moment on behavior of such structures is not known. Methods of analysis do not reflect actual behavior of beam structures during their use and failure. Performed experimental investigations and inspection of existing structures demonstrated that damages may appear in the structures during their use if action of the torsional moment is not taken into account in design of reinforced concrete structures. Especially it is the case in pre-cast reinforced concrete beams on which slabs of 2T type are supported. In analysis of reinforced concrete members subjected to simultaneous action of bending and torsion, the shape of cross-section of members, the type of loading, ratio of the bending moment (M) to shear the force (V) and the torsional moment (T) are of great influence. The principle stresses are generated...
Tension-Stiffening Model Attributed to Tensile Reinforcement for Concrete Flexural Members
Procedia Engineering, 2011
Adequate modeling of reinforced concrete (RC) cracking and, particularly, post-cracking behavior (tension-stiffening), as one of the major sources of a nonlinearity, is the most important and difficult task of the deformation analysis. Present investigation aims at deriving a steel-related tension-stiffening relationship based on the smeared crack approach. The analysis uses the results of the experimental program performed by the authors. It consisted of three beams reinforced with three deformed bars of 18, 14 and 10 mm in diameter. Other characteristics of the beams were almost identical. An inverse technique has been developed to derive a steel-related tension-stiffening model from the moment-curvature diagrams of the beams. The constitutive relationship recommended by Eurocode 2 was assumed for the compressive concrete, whereas the elastic-brittle behavior was taken for the concrete in tension. The tensionstiffening effect was modeled by the stress-strain relationship of the tensile reinforcement. For the model assumed, total stresses in the tensile reinforcement consist of genuine stresses corresponding to the average strain of the steel and the additional stresses due to tension-stiffening. It was found that the tension-stiffening stresses, normalized in regard to reinforcement area, have become almost independent on the amount of reinforcement. The proposed technique is capable of investigating the tension-stiffening behavior in RC flexural members.
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.
Flexural Behavior of Partially Pretensioned Continuous Concrete Beams
2017
This paper describes flexural behavior of two spans continuous rectangular concrete beams reinforced with mild steel and partially prestressing strands, to evaluate using different prestressing level and prestressing area in continuous prestressed beams at serviceability and ultimate stages. Six continuous concrete beams with 4550 mm length reinforced with mild steel reinforcement and partially prestressed with two prestressing levels of (0.7fpy or 0.55fpy.) of and different amount of 12.7 mm diameter seven wire steel strand were used. Test results showed that the partially prestressed reinforced beams with higher prestressing level exhibited the narrowest crack width, smallest deflection and strain in both steel and concrete at ultimate service load, the deflection decreased by (3.60% & 32.49%) and the crack width decreased by (20.0%) and (75.0%) when increasing the prestressing level from (0.55fpy.) to (0.7fpy.) for beams reinforced with one and two strands respectively. Deflecti...