AbstractThis paper describes the development of numerical and finite-element (FE) models for investigating the behaviors of short ultrahigh-performance fiber-reinforced concrete (UHPFRC) columns ...under concentric or eccentric loading conditions. A generic mechanic-based partial-interaction (PI) approach that is applicable to both flexural and axial members manufactured by conventional fiber-reinforced concrete has been suitably modified to analyze the structural response of the short UHPFRC columns. Moreover, FE modeling was also conducted to study the behaviors of UHPFRC members subjected to different loading conditions. Both models aim to generate load-axial deflection (P-δaxial) or load-midheight deflection (P-δmid) relationships for concentrically or eccentrically loaded columns, as well as a load-midspan deflection (P-δmid) relationship for a beam subjected to three-point bending. Simulated results display an excellent agreement with test results, and the model can accurately predict the structural response of the UHPFRC columns. To aid in the development of a design guideline for the short UHPFRC columns, a load-moment (P-M) interaction envelope generated by the numerical model is proposed, and it shows a good correlation to the experimental results.
The composite beam with inverted-T steel girder and UHPC slab connected by studs arranged in the web of the girder was developed to further the economy in material and best exploit the properties of ...UHPC. However, the composite beam may experience premature failure due to the occurrence of slip at the shear interface. This so-called partial interaction needs to be addressed in the flexural design for field application of the developed composite beam. The present study proposes a nonlinear analysis method for the evaluation of the flexural behavior of the composite beam considering partial interaction. An analysis method using the Fourier series to approximate the internal forces in the beam considering slip is coupled with a sectional analysis method accounting for inelastic behavior of the steel girder and nonlinear behavior of UHPC. The model considering the slip effect induced by partial interaction is seen to realistically and accurately simulate the actual behavior of the composite beam.
•Shear connection with UHPC slab by studs welded on inverted-T steel girder flange.•Consideration of slip effect due to partial interaction at shear interface in analysis.•Analysis based on linear interaction theory to approximate internal forces.•Nonlinear analysis model coupling partial interaction and sectional layered analyses.•Realistic and accurate simulation of actual flexural behavior of composite beam.
The objective of this work is to provide insight into the expected slip demand in the shear connection of composite steel–concrete beams through the use of a numerically efficient nonlinear beam ...model previously validated by comparisons with experimental tests. The results of a parametric analysis involving 1680 simply supported beams are illustrated to investigate the influence that various design parameters (i.e. span length, degree of shear connection, steel beam and concrete slab cross-section geometry, connection distribution, dead load to live load ratio, propped and unpropped construction sequences, and concrete strength) and modelling parameters (i.e. shear connection representative strength and constitutive parameters) have on the slip demand. It is observed that, for a given shear connection degree, the most important parameters are the construction sequence, the span length, and the steel section shape. In addition, the shear connection distribution can have an important effect and non-uniform shear connection distributions with more connectors near the supports might be effective in limiting the slip demand. The results illustrated in this work can be a support for more efficient designs of the shear connection in composite steel–concrete beams and a basis for possible improvements of their current design recommendations.
•Shear connection slip demand evaluated in composite beams at the ultimate limit state•Effect and importance of various design parameters analysed and illustrated•Influence and significance of modelling assumptions considered and discussed
► Mechanics based hinge for RC beams with multiple cracks is developed. ► Hinge based on shear-friction and partial-interaction theories. ► Used to accurately simulate uncracked, cracked and ...softening behaviour.
The formation of hinges in reinforced concrete beams is important as hinges influence the ability of the beam and, subsequently, the frame to absorb energy and resist extreme loads such as hurricane or seismic loads. A common approach for quantifying the rotational capacity of beams at the ultimate limit is to use a strain based moment–curvature analysis combined with an empirical hinge length to determine the rotation capacity of the member. Being empirically based, this approach is very restrictive as it can only be applied within the bounds of the tests from which they were derived. In this paper, a mechanics displacement based hinge approach is described that can simulate the formation of cracks, the discrete rotation at each individual crack and the formation of wedges. Being mechanics based, this hinge model can be applied to any type of reinforced concrete, such as those with brittle reinforcement and also to all strengths of concrete. This mechanics based model is shown to have good agreement with test results and can be used at all stages of loading from serviceability to failure. Furthermore, it can also used to develop closed form solutions that do not require the moment–curvature assumption of full interaction but specifically allow for partial interaction that is slip between the reinforcement and the concrete.
In this study, the photon interactions of WO3-TeO3 glass system have been calculated using WinXCom program at energy 1 keV-103 keV. The mass attenuation coefficient (μm) and the partial interactions ...were presented. The results show that the values of μm increased toward the decrease of gamma ray energies, indicates the dependence of the mass attenuation coefficient values on the photon energy. The partial interactions found that three energy ranges relative to the partial processes photoelectric absorption, Compton scattering and coherent scattering. These glass sample was observed that the photoelectric absorption found to be the main interaction of energy range. The discontinuous of glass sample illustrate that it occur from photoelectric absorption edge of sample element compositions at low photon energies. The coherent scattering found to be significant at low photon energy and rapidly decreases with increasing of photon energy but the Compton scattering, the values was slightly increase with increasing of photon energy.
•Non-prismatic beam behaviour poorly predicted by partial/full-interaction models.•Combined-interaction model accounts for both partial- and full-interaction regions.•The combined-interaction method ...provides good deflection predictions.•Average and maximum crack width predictions compare favourably with test results.•Method allows design for serviceability criteria of optimised concrete structures.
Interest in the shape optimisation of concrete members is increasing alongside the availability of fabric formwork as a relatively simple technique to cast non-prismatic concrete structures. Research has shown that up 40% of concrete can be saved when shape optimised concrete beams are cast in fabric forms. However, optimisation results in members with non-uniform cross-sections and the resulting beam is less stiff than an equivalent strength prismatic beam. Serviceability, rather than strength, may govern the design of such members and therefore understanding the serviceability behaviour (deflection and cracking) of shape optimised concrete members becomes is a critical design consideration. There are many methods which can be used to evaluate serviceability behaviour of reinforced concrete beams, including the full-interaction method, which assumes no slip between the reinforcement and the surrounding concrete, and the partial-interaction method which accounts for slip. The full-interaction method is based on a smeared crack approach and so is unsuited for the prediction of cracking behaviour. The partial-interaction method, on the other hand, assumes that cracks form through bond-stress transfer only. In the case of non-prismatic concrete beams, the cracking capacity varies along the member. Therefore, cracking can occur over extended regions (full and partial bond interaction regions) and so it can be argued that neither of these models is fully suitable for the prediction of deflections and cracking of shape-optimised concrete beams. In this paper, a novel combined-interaction method is, for the first time, presented to predict the serviceability behaviour of non-prismatic statically determinate concrete beams by simulating both full and partial bond interactions at different cracked and uncracked regions along the length of the member. In order to validate this approach, two non-prismatic simply supported beams were cast and tested. The test results for deflections, crack widths and crack spacings were in good agreement with the predicted results.
A new one dimensional finite element model based on a higher order beam theory is presented for the analysis of composite beams taking into account the effect of longitudinal as well as vertical ...partial interaction between the adjacent layers. The proposed method models the transverse shear deformation of the beam components in a refined manner. A third order variation of the axial displacement of the fibres over the beam depth is taken to have a parabolic variation of shear stress which is also made zero at the beam top and bottom surfaces. In the proposed FE model, there is no need of incorporating any shear correction factor and the model is free from shear locking problem. In addition to correctly predicting the global responses of the beam, the model can predict better distribution of stresses than the existing models based on Euler–Bernoulli or Timoshenko beam theory. Many new results are presented as there is no published result on the present problem based on higher order beam theory.
► 1-D Higher Order Beam Finite Element model has been presented. ► The partial longitudinal as well as transverse interaction has been modelled. ► There is no need to use any shear correction factor in the proposed model.
A force-based finite element formulation for the buckling analysis of two-layer composite beam structures with partial interaction is presented. The geometrically nonlinear beam elements possess a ...single flexible shear interface and each layer is modelled by means of Timoshenko’s theory. The formulation relies on a hybrid variational principle of complementary energy only involving force/moment-like variables as fundamental unknown fields. The approximate field variables are selected such that all equilibrium differential equations are satisfied in strong form. The inter-element equilibrium, as well as Neumann boundary conditions are enforced by means of the Lagrangian-multiplier method. The accuracy and effectiveness of the proposed formulation is demonstrated through the analysis of several numerical tests.
A simplified static procedure is proposed for analysing and designing composite beams with interlayer slip. The method is parallel to the Eurocode 5 method, but it is general in nature and can be ...applied to arbitrary boundary and loading conditions. In contrast with Eurocode 5, a general and correct way of choosing the effective beam length of the problem is given by the present procedure, which is that the effective beam length equals the buckling length that is found in the corresponding column buckling problem. The procedure predicts the deflections and internal actions and stresses, in principle by replacing the fully composite bending stiffness (
EI
∞) with the effective (partially) composite bending stiffness (
EI
eff) in the expressions for these quantities in the corresponding fully composite beam. This effective bending stiffness depends on two non-dimensional parameters: the composite action parameter (shear connection stiffness) and the relative bending stiffness parameter. The method is applied to a number of simple practical cases and the results obtained have been compared with the exact values. The applicability of the simplified analysis procedure was found to be very good, except for interlayer shear stresses. The error in the Eurocode 5 procedure, as compared with the method proposed in this paper, can in some cases be up to almost 30% depending on the boundary conditions.
Fibre-reinforced polymer (FRP)-to-concrete bonded interfaces are susceptible to bond failure in the concrete at the interface. This paper presents the details of a partial interaction model that is ...capable of analysing such bond failure in FRP-to-concrete joints. The model is driven by displacing the slip between the FRP and concrete at the loaded end of the joint and is thus able to capture unloading of the bonded interface. Such unloading is due to a reduction in the available length of the bonded plate on account of progressive plate debonding. A bond stress versus slip model is calibrated from test results and incorporated into the partial interaction model. Predictions of strain, bond stress and slip along the length of the bonded plate are produced and the results are found to correlate with test measurements. Finally, parametric studies on a typical joint enable insights to be gained on the parameters used to define the bond-slip model.
•Numerical modelling of FRP-to-concrete bonded interfaces using a mechanics model.•Theory and bond-slip relationships of FRP-to-concrete bonds.•Parametric study on key variables influencing interfacial behaviour.
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