NONLINEAR FINITE ELEMENT ANALYSIS OF COMPOSITE CONCRETE BEAMS

2001

To study the nonlinear response of composite concrete beams, a finite element analysis is presented in this work. Material nonlinearities as a result of nonlinear response of concrete in compression, crushing and cracking of concrete, strain softening and stiffening after cracking, yielding of reinforcement, bond-slip, shear-slip, and dowel action between the precast concrete beams and the cast-in-situ slabs are considered. A biaxial concrete model is adopted. Concrete is treated as an orthotropic material with smeared rotating crack model. The steel reinforcement is assumed to be in a uniaxial stress state and is modeled as a bilinear material. A two-dimensional plane stress finite element type is used to model the concrete. Reinforcement is represented by one-dimensional bar elements. Bond-slip and dowel action is modeled by using fictitious linkage elements with two springs at right angles. Shear-slip is modeled by using shear transfer interface elements with appropriate stiffness values. The validity of the proposed modeling and the capabilities of the computer program written are examined by analyzing several published experimental reinforced concrete specimens. Comparison between the results obtained by the finite element computer program and available experimental results of composite concrete beams is made. The analytical results compare satisfactorily with the experimental ones. A parametric study deals with shear and bending moment capacity of composite concrete beams is presented.

The non-linear behavior of reinforced concrete (RC) beams till the ultimate failure is a complicated phenomenon due to the involvement of heterogenic material properties and cracking behavior of concrete. Behavior prediction of reinforced concrete elements till failure is usually carried out using experimental testing, and the observations are recorded only at critical locations due to restriction in cost of testing equipment and accessories. In order to avoid the destructive testing, reduction of the cost of materials and manpower, the behavior prediction of RC beams is generally carried out using numerical methods. This paper presents study on non-linear flexural behavior of reinforced concrete beams. Non-linear finite element analysis of reinforced concrete beams under flexural loading is presented in this paper. Finite element modelling of reinforced concrete beams is carried out using discrete reinforcement modelling technique. The capability of the model to capture the critical crack regions, loads and deflections for various loadings in reinforced concrete beam has been illustrated. Comparison is made between the experimental results and finite element analyses with respect to initial crack formation and the ultimate load capacity of beams. The results obtained in the present study show close agreement with those in the available literature.

2015

This work aims to develop and identify a new model for reinforced concrete joint element subject to cyclic loadings. Based on experiments and 3D numerical modeling, a simplified model of RC beam-column joint is introduced (within the framework of macro-element). In a first experimental study, this joint will be tested under reverse cyclic loading applied at the beam tip to identify its behavior under this kind of loading in terms of strength, stiffness and ductility. In parallel of experiments, a finite elements model of the joint based on 3D finite elements is presented to highlight and define the nonlinear mechanisms involved in the ruin of the assembly. This step will confirm the experimentally observed phenomena: damage, friction, plasticity. Secondly, a simplified macro-element model for beam-column joint, associated to a nonlinear behavior, is introduced to reflect the response of the joint under cyclic loading loads. Model parameters will be identified from experimental resul...

Diyala Journal of Engineering Sciences, 2013

This paper presents a nonlinear finite element computer program. ANSYS version 12.0 developed for the analysis of composite steel-concrete beam. A three-dimensional finite element (FE) model has been developed in this work. The analytical results of load-deflection response have been compared with available experimental tests. In general good agreement between the finite element solutions and experimental results have been obtained. Parametric studies have been carried out to investigate the effect of some important material and geometrical parameters. These parameters included the effect of shear connectors number, concrete grade, thickness to width ratio of concrete slab, the ultimate load for shear connector and effect of yield strength of Steel beam. It was found that, as the compressive strength of concrete increases from 20 MPa to 70 MPa the ultimate load increases by about 20% and also an increase in the thickness to width ratio (t/B) of concrete slab from 0.1 to 0.3 lead to ...

Computer Methods in Applied Mechanics and Engineering, 1979

Due to the corrosion that occurs in internal steel reinforcement; many of steel reinforced concrete structure are at risk of collapse. The budget that will be developed to address this risk in terms of replacement or repair of damaged concrete structures will be very high for the owner or responsible authorities. Alternatives to bare steel have been used including stainless steel, galvanized steel, epoxy-coated steel and cathodic protection, with limited effectiveness. The characteristics of fiber reinforced polymer (FRP) bars like the high tensile strength, inability to corrode, and light weight; it has become the focus of decision-makers to use it instead of steel in internal reinforcement for future concrete structures. In this research, we have investigated flexural behavior in reinforced concrete beams with bars from bars from carbon fiber-reinforced polymer (CFRP), bars from high tensile steel (HTS), and glass fiber-reinforced polymer (GFRP) under static load. Two groups from samples were used, in the first group will show the effect of the type of reinforcement. In the second group will show the effect of the type of reinforcement with different concrete strength. It found these kinds of materials to be very is effective to deal with analysis and the proposed simulation of the material in this study are able of forecast the real behavior of reinforced concrete beam by FRP bars in terms of failure load, and loaddeflection behavior.

IJMER

This study presents theoretical investigation that reinforced concrete and composite construction might be suitably combined to give a new structural material : composite reinforced concrete. To study theoretically the composite beam, non-linear three-dimensional finite elements have been used to analyze the tested beam. The 8-node brick elements in (ANSYS) are used to represent the concrete, the steel bars are modelled as discrete axial members connected with concrete elements at shared nodes assuming perfect bond between the concrete and the steel. The results obtained by finite element solution showed good agreement with experimental results. The main objective of the present investigation is to carry out a nonlinear analysis of reinforced concrete beams resting on elastic foundation. Material nonlinearities due to cracking of concrete, plastic flow, crushing of concrete and yielding of reinforcement are considered. Foundation representation is assumed linear using Winkler model. The reinforced concrete beam is modelled by using three dimensional finite elements with steel bars as smeared layers. The examples have been chosen in order to demonstrate the applicability of the modified computer program (Dynamic Analysis of Reinforced Concrete Beams on Elastic Foundations DARCEF ) by comparing the predicted behaviour with that from other experimental and analytical observations. The program modified in the present research work is capable of simulating the behaviour of reinforced concrete beams resting of Winkler foundation and subjected to different types of loading. The program solutions obtained for different reinforced concrete beams resting on elastic foundations are in good agreement with the available results. Maximum percentage difference in deflection is 15 %

An analytical model, which can simulate the biaxial description of the nonlinear behavior of reinforced concrete structures, is introduced. The behavior of concrete is assumed orthotropic inside the ultimate failure surface and a compressive softening law of concrete is presented. The behavior of cracked concrete is simulated using the smeared crack model, which the tension stiffening effect based on a cracking criterion derived from the fracture mechanics principles is considered. A computer program is developed for analyzing the over and under-reinforced concrete beams. Several parameters such as the non-linearity proprieties, the cut off and tension stiffening models and shear retention factor are studied. The correlation between analytical and experimental results shows the validity of the proposed models and the significance of various effects. The global responses are evaluated to verify simultaneously the reliability of the proposed model and the performance of the numerical program.

Engineering Structures, 2017

This paper presents an efficient computer method for nonlinear inelastic analysis of composite steelconcrete beams with partial composite action. The proposed formulation is intended to model the combined effects of partial composite action and distributed plasticity using only one 2-noded beam-column element per structural member. Based on elasto-plastic cross-sectional analyses the behaviour model is able to take into account the effects of partial composite action between the concrete slab and the steel beam. Gradual yielding throughout the cross-section is described through basic equilibrium, compatibility, material and shear connection nonlinear constitutive equations. Tangent flexural and axial rigidity of the cross-section are derived and then using the flexibility approach the elasto-plastic tangent stiffness matrix and equivalent nodal loads vector of the beam-column element including the shear deformability of the partially connected composite beam has been developed. The proposed nonlinear analysis formulation has been implemented in a general nonlinear static purpose computer program, NEFCAD. Advanced finite element simulations have been conducted by using the specialized software for nonlinear analysis of structures, ABAQUS. Several computational examples are given to validate the accuracy and efficiency of the proposed method by comparing the results predicted by NEFCAD with those given by the ABAQUS software and other results retrieved from the open literature.

Engineering Structures, 2012

In this paper, a finite element (FE) model for nonlinear analysis of reinforced concrete (RC) beams, considering shear deformation, is developed. The model is based on the Timoshenko Beam Theory and utilizes 3-noded bar elements with a total of 7 degrees of freedom. The Fiber Model is adopted, with the element section discretized into overlaid concrete and longitudinal reinforcement layers. Transverse reinforcement, when present, is considered to be smeared and embedded in the concrete layers. The Modified Compression Field Theory with some modifications is utilized for the material constitutive models, and a tension-stiffening model developed by the authors is included. The FE model was implemented into a computer program named ANALEST, developed by the authors, which allows for material and geometrical nonlinear analysis of RC beams and frames. The proposed model is validated via comparison with experimental results from tests on simply supported and continuous RC beams. Comparisons with numerical results from a Bernoulli-beam model are also included, and a few recommendations regarding the use of different FE models are given at the end.

Structures, 2021

This paper presents an experimental investigation and nonlinear finite element analysis (NLFEA), using the numerical analysis tool ANSYS © , carried out on the shear and diagonal cracking effect on the behaviour of reinforced-concrete (RC) beams made of normal strength concrete (NSC) and highstrength concrete (HSC), with and without transverse reinforcement. Beams were tested using fourpoint bending, by means of digital image correlation (DIC). In the experimental setup, the shear zone was digitised using a high-resolution camera to assess the deformation of concrete in the compression zone and to measure the diagonal crack widths. The results show that transverse reinforcement does efficiently control the diagonal crack width, increases the shear capacity of the beams, shifts the mode failure from shear to flexure, and significantly improves the ductility of beams in the ultimate state particularly when using HSC, given the better quality of the bond developed in the concrete with steel reinforcement. The values of ultimate shear strength obtained experimentally were compared to the corresponding empirical values available in the literature. Furthermore, detailed 3D finite element analysis (FEA) was used to predict the load-deflection response, the ultimate load, the cracking load, the ultimate deflection, the maximum diagonal crack widths and the cracks patterns in RC beams. The difference values between the numerical and experimental values range from −11.08 to +0.6%, from −2.02 to −0.52% and from −13.27 to −1.01% for cracking load, for ultimate load and for ultimate midspan deflection, respectively. The ratio of the predicted to experimental maximum diagonal crack width for the beams ranged between 0.95 and 1.06. Also, a good agreement between the experimental and numerical crack patterns was achieved. Consequently, the FEA model is able to predict the shear response of RC beams with a good accuracy.