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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...
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Citations
... The degree of a composite action in a composite member is related to the geometrical and mechanical properties of the concrete slab [1,2].Composite beams are maybe of different materials like steel and concrete, which are brought together to work as a composite system. From early load stages, as the shear causes slip to develop between the two parts, the composite beam behaves as a partially composite member [3].In ultimate strength analysis, such as the total deformation, the normal elastic strain, the maximum principal stress, the shear stress and the strain energy of the steel section are been identified. However composite structures are usually loaded well below levels that would cause failure and the behaviour of the steel and concrete can be considered as linear. ...
The composite structures are extensively used for its high specific strength, structural stiffness and less weight. A composite beam comprises of concrete slab at the top with a steel beam of I shaped cross section beneath the slab. In this research a three dimensional composite beam is modelled to study the variation in thickness of concrete slab and steel section subjected to uniformly distributed load using finite element analysis. The support conditions of the structure are modelled as fixed beam on both the ends. Relative study is proposed on three different concrete slab thicknesses of 80,100 and 120mm respectively with steel I section beams. The parameters involves total deformation, maximum principal stress, shear stress, normal elastic strain and strain energy in the composite T beam at midspan are reported. It also attempt to conclude that the longitudinal compressive stresses in concrete slab had a non-uniform distribution of stresses along the cross section and it also produces positive bending moment. Shear stress across the sections must be checked to ensure that concrete components act compositely.
... Composite construction consists of using two materials together in one structural member and using each material to its best use. The number of combinations is almost endless; steel and concrete, timber and concrete, timber and steel, precast and cast-in-place concrete, etc… (Al-Sherrawi, 2000) [1]. ...
A composite steel-concrete beam is constructed from a concrete slab casted on a steel beam and joined together. Under positive or negative bending moment, the slab will behave as the top flange of the composite beam resisting the compressive or tensile stresses. To study the effect of the variation in degree of partial interaction between concrete and steel on shear lag in a continuous composite beam under different types of loadings, a three-dimensional linear finite element analysis is used.
A comparison with an experimental test has been performed to validate the finite element analysis results. In general, good agreement between the finite element solution and the experimental result has been obtained. The maximum difference in the deflection was about (3.8%).
A parametric study has been carried out to investigate the effect of the partial interaction on the shear lag, effective with and maximum concrete and steel stress. It was found that the partial interaction in a composite steel-concrete beam has a minor effect on the effective slab width.
... It should be obvious that if the steel beams in a composite bridge deck are spaced quite apart from each other, as shown in Fig. 1, the entire concrete slab will not be effective as a compression flange in the composite action of the bridge deck (Al-Sherrawi, 2000) [1]. It is well known that the uneven deformation of the wider top flange (concrete) can produce an uneven distribution of the longitudinal stresses under symmetrical bending. ...
A composite beam is made up of a reinforced concrete slab connected to a steel beam by means of shear connectors. If the slab was wide and the composite beam is under positive bending moment, it is evident that the simple beam theory does not strictly apply because the longitudinal stress in the concrete flange will vary with distance from the beam web, the flange being more highly stressed over the web than in the extremities. In this paper a three-dimensional linear finite element analysis, using ANSYS program, is done to study the effect of the breadth of the slab on the effective slab width and stress distribution across the slab width (shear lag) of composite steel-concrete beams. The stresses of concrete and steel are compared with stresses obtained from T-beam theory for variable breadths of concrete slab. Effective width for composite beams with different breadth under various loads has been drawn.
... From early load stages, as the shear causes slip to develop between the two parts, the composite beam behaves as a partially composite member (Al-Sherrawi, 2000) [1]. ...
A composite beam includes a concrete slab and a steel beam, which are connected by shear connectors. Under positive bending moment, the longitudinal compressive stresses in the concrete slab have a non-uniform distribution along the cross section because of the shear lag effect. In this work a three-dimensional linearly elastic finite element analysis has been done to study the variation of shear lag due to loading type in a composite steel concrete beam. Three types of loading cases have been investigated in this study; concentrated load, line load and uniformly distributed load. From results obtained, it was found that the longitudinal stresses distribution in the concrete slab at the midspan of a simply supported composite beam was markedly different from the uniform distribution assumed in T-beam theory and shear lag clearly affected by loading type.
... Composite construction consists of using two materials together in one structural unit and using each material to its best advantage. The number of combinations is almost endless; steel and concrete, timber and concrete, timber and steel, precast and cast-in-place concrete, etc? (Al-Sherrawi, 2000) [1]. ...
... However, the real attraction of composite construction is based on having an efficient connection of the steel to the concrete, and it is this connection that allows a transfer of forces and given composite member unique behavior [2]. Although the word composite may refer to all kinds of different materials connected together, in this study the term composite beam means steel beam attached to a reinforced concrete slab by means of mechanical connectors (shear connectors) as shown in Figure (1). The functions of these connectors are to transfer horizontal and normal forces between the two components, thus sustaining the composite action. ...
... Material properties of the Yam and Chapman composite beam are summarized in Table ( 1). In this analysis the symmetry has been used by using half span of the beam. ...
A composite section is made up of a concrete slab attached to a steel beam by means of shear connectors. Under positive bending moment, part of the slab will act as the flange of the composite beam resisting the longitudinal compression. In this paper a three-dimensional linear finite element analysis, using ANSYS program, is employed to evaluate and determine the actual effective slab width of a partially composite steel-concrete beam with variable degrees of partial interaction. Eight node isoparametric elements have been used to model the reinforced concrete slab, while the steel reinforcing bars are modeled as axial member (bar element) connecting opposite nodes between brick element with full bond assumption. The steel beam is modeled by four-node isoparametric shell elements, a spar bar element which has two end nodes with three translation degrees of freedom at each end has been used to model the shear connectors to resist uplift. The effect of dowel action of shear connector through the interface between top flange of the steel girder and concrete slab is modeled by combin element; the interface between two surfaces is modeled by contact element. From analysis results, the stresses of concrete and steel are compared with stresses obtained from T-beam theory for variable degrees of partial interaction. From results obtained, it was found that, the partial interaction of composite beams is a minor effect on effective slab width.
... In actual practice with a composite concrete beam and slab construction, no composite action is impossible because there are always some degrees of bond and friction between the slab and the beam. Similarly, full composite action is impossible because there is always some small degree of slip, no matter how rigidity the shear connection may be designed [Al-Sherrawi, 2000]. Fig. 3 shows the strain diagram in a composite concrete beam with different types of interaction. ...
Composite concrete beams construction separate widely in buildings and bridges for economical purposes. Some international specifications and codes present design rules to predict nominal shear and flexural strength for a composite concrete beam, one of them is ACI 318M-14. The contributions of the concrete slab and composite action to the vertical shear and moment strength of composite concrete beams are not considered in current design specifications and codes. In this paper, a comparative study deals with shear and bending moment capacity and shear stress of composite concrete beams is presented. The work includes a comparison between experimental tests results, ACI 318M-14 nominal shear and flexural strengths and finite element results. The ACI 318M-14 failed to predict the ultimate capacities, while the finite element analysis results compare satisfactorily with the experimental ones.
... The main goal of this research was to verify the finite element procedure presented by Al-Sherrawi (2001) [1] to represent the interface between two concretes cast at different times under shear. A two-dimensional plane stress finite element type had been used to model the concrete specimens. ...
... At the interface, there can be separation, closing of the gap, and slipping between the two concretes. A four-noded interface element as shown in Figure 5 had been used to model this behavior between concrete elements of the two parts [1]. Two in-plane translational degrees of freedom per node have been considered. ...
... Interface element[1] ...
This article is focused on the numerical analysis of the shear resistance at an interface between two concretes cast at different times, which performed by means of a nonlinear finite element program. A linkage element and an interface element had been used, in this study, to model the dowel action and the concrete shear transfer at the interface, respectively. The finite element idealization had been verified by the analysis of several specimens tested by others. The comparison shows a good concordance with the experimental results within acceptable ranges.
... The efficiency of the present work is demonstrated by the use of the computer program (QHA2) (Al-Aquly 2002), which analyzes the composite beam as a one-dimensional problem, is assessed by comparing with the experimental results obtained from previous researchers. Also, a comparison with the two-dimensional analysis using the program (MHND) written by (Al-Sherrawi 2000) and the software (ANSYS 5.4) and three-dimensional analysis using the software (ANSYS 5.4) is shown. ...
In the present study, a general nonlinear one-dimensional finite element beam model is developed for the analysis of composite beams. The proposed model is based on the partial interaction theory of composite beams where the flexibility of shear connectors is allowed. By using a layered approach for the composite beam cross-section and including the material nonlinear behavior of concrete, steel, shear connector and reinforcing steel, the proposed method of analysis is capable of predicting the response of composite beams throughout the elastic, inelastic and ultimate load ranges in one complete analysis. Numerical case studies are presented to demonstrate the validity and applicability of the present method. The results are compared with experimental and analytical or numerical results obtained by other investigators. Also the results are compared with ANSYS package results. The maximum differences in deflection and slip for the examples considered are 12% and 14% respectively when compared with ANSYS and 5% and 11% when compared with experimental work. Accordingly, the proposed nonlinear finite element model represents an efficient and simple tool for the full range analysis of composite beams.
... To achieve the requirements of the present work, a computer program (MHND) has been written based on the orthotropic concrete constitutive models (Al-Sherrawi, 2000). It is coded in Microsoft Visual Basic 6.0. ...
To study the nonlinear response of composite concrete beams, a finite element analysis is presented. 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.
Comparison between the results obtained by the finite element and available experimental results of composite concrete beams is made. The results compare satisfactorily with the experimental ones.
Concrete is the most widely used construction material which has three phases for analysis as aggregate phase, paste phase and transition phase. Out of the three phases, transition phase is the weakest. This weak transition phase and movement of inherent cracks makes the concrete poor in tension. This characteristic property of concrete has been the basic idea for this research work. In this experimental study, the conventional concrete in the tension zone is replaced with coconut shell concrete. This creates a composite concrete element which has two layers, conventional concrete in the compression zone and coconut shell concrete in the tension zone. This research deals with the study of this composite concrete element for various mechanical properties, without using steel reinforcement in it.
