1,720,975 research outputs found
Partial interaction behaviour of composite steel-concrete members at elevated temperatures accounting for geometric nonlinearities
No full textThis paper presents a numerical model for the analysis of composite steel-concrete beams at elevated temperatures accounting for both longitudinal and transverse interaction within the framework of nonlinear finite deformation theory. A reduced formulation, useful for solving structural problems, is then derived on the basis of the theory of small strain and moderate rotations. The numerical solution proposed relies on the use of the finite element method. As the scope of this study is restricted to moderately elevated temperatures, elastic material properties are assumed for all materials while still accounting for their degradation with temperature. A bilinear constitutive model is adopted for the transverse interface connection to reflect the more realistic case in which an extremely high connection stiffness exists for the bearing condition of the concrete slab against the steel joist, and a relatively weaker stiffness is manifested when the joist and slab are separating. A brief numerical example is then presented for a beam configuration subjected to a thermal distribution typical of real fire scenarios and pinned at its ends
The effects of the shear deformability of composite beams on their long-term and ultimate behaviour
No full textThis paper presents a comparative study between the performance of three different beam models to describe the long-term and ultimate behaviour of composite members with partial interaction. In particular, these models are derived coupling by means of a flexible shear connection two Euler-Bernoulli beams (commonly referred to as Newmark beam model), a Euler-Bernoulli beam and a Timoshenko beam, and two Timoshenko beams, respectively. The numerical solutions are obtained by means of the finite element method. The effects of including the shear deformability of the steel joist is discussed at service conditions based on an extensive parametric study carried out on approximately 100 realistic three-span composite beams. The differences in using the three beam models in predicting the ultimate composite behaviour is then discussed using experimental results available in the literature as benchmark problems
Partial interaction analyses of composite steel-concrete girders subjected to combined bending and shear
No full textThree different beam models for the linear viscoelastic analysis and nonlinear analysis of steel-concrete composite girders including partial interaction are compared, i.e., models derived by coupling with a deformable shear connection two Euler-Bernoulli beams (only flexural deformability and flexural failure mode), an Euler-Bernoulli beam to a Timoshenko beam (addition of shear deformability and shear failure mode for one component only), and two Timoshenko beams (addition of shear deformability and shear failure mode for both components). Results of linear analyses involving 200 simply supported and three-span compo-site girders as well as results of nonlinear analyses involving experimentally tested simply supported and con-tinuous beams are illustrated to evaluate the effects of shear in the steel and slab components at various load levels. Results show that differences between the three models are significant in many cases
General method of analysis for composite beams with longitudinal and transverse partial interaction
No full textThis paper presents an analytical formulation for the analysis of two-layered composite beams with longitudinal and vertical partial interaction. The particularity of this model is its ability to incorporate an interface connection deforming both longitudinally, i.e., along the beam length, and vertically, i.e., transverse to the connection interface, which is modelled by means of a uniformly distributed spring. The novel formulation is based on the principle of virtual work expressed in terms of the displacement field consisting of the vertical and axial displacements of the two layers; for completeness, the proposed model is presented in both its weak and strong forms. The partial interaction problem is then solved by means of the finite element method. A parametric study is presented to investigate the effects of different combinations of longitudinal and transverse connection rigidities on the overall structural response. For the purpose of these simulations, a bi-linear constitutive model has been specified for the transverse interface connection to reflect the more realistic case in which two different responses are observed in the transverse interaction, one in which one layer is bearing against the other one, one when the two layers are separating. An iterative procedure has been proposed to obtain the convergence to the final solution. (c) 2006 Elsevier Ltd. All rights reserved
A generic modelling of composite beams with longitudinal and vertical partial interaction
No full textABSTRACT
This paper presents a novel analytical formulation for the analysis of composite beams with longitudinal and vertical partial interaction in which the interface connection deforms both longitudinally, i.e. along the beam length, and vertically, i.e. transverse to the connection interface. The theoretical model is derived from the principle of virtual work, using the displacement method. Based on the weak form of the problem, a novel finite element is proposed and applied for the analysis of a propped cantilever subjected to a point load applied to the lower layer at mid-span. In this application, the vertical interface connection is modelled by means of a bi-linear constitutive relationship to reflect the more realistic case in which the vertical connection stiffness is several orders of magnitude greater when the layers are in contact, compared with the case of layers’ separation. An iterative procedure has been proposed to obtain convergence to the final solution
Displacement-based formulations for the partial interaction analysis of composite beams accounting for time effects
No full textThis paper presents a comparative study of available displacement-based modelling techniques for the
analysis of steel-concrete composite beams with partial shear interaction, which include the finite difference
method, the finite element method, the direct stiffness method and the exact analytical model. Both shortand
long-term analyses have been considered in order to provide an indication of how these affect the
accuracy of the predictions. For the implementation of the finite difference method and of the finite element
method, discretisations in both space and time domains are required, while only the time discretisation
needs to be specified for the direct stiffness method and the exact analytical solutions. The time-dependent
behaviour of the concrete has been modelled by means of the age-adjusted effective modulus method
(AEMM) while the remaining materials at the cross-section have been assumed to behave in a linear-elastic
manner. The results obtained using these formulations are qualitatively compared and their accuracy is
estimated adopting the exact analytical model as a benchmark reference with the objective of establishing
the minimum spatial discretisations required to keep the error within an acceptable tolerance. These
comparisons are carried out for simply-supported beams, propped cantilevers and fixed-ended beams, from
which the behaviour of these formulations in the modelling of continuous beams can also be deduced
Longitudinal and transverse partial interaction analysis of composite beams accounting for time effects and shear-lag effects
No full textABSTRACT: This paper presents a novel analytical formulation for the analysis of composite beams with longitudinal and vertical partial interaction which accounts for time and shear-lag effects. The particularity of this model relies on the ability of the interface connection to deform both longitudinally and vertically, i.e. transverse to the connection interface. All materials are assumed to be linear-elastic except for the concrete, whose time-dependent behaviour, is modeled by means of a step-by-step procedure. The theoretical model is derived using both the principle of virtual work and, relying on the weak form of the problem, the finite ele-ment method. Their ability to accurately depict the partial interaction behaviour is then discussed using simple structural systems. Curvature locking problems, which have been observed in the finite element simulations, are discussed and their origins are demonstrated analytically
Displacement-based formulations for composite beams with longitudinal slip and vertical uplift
No full text
Displacement-based formulations for the partial interaction of composite beams accounting for time effects
No full textINTRODUCTION
This paper presents a comparative study of available displacement-based modelling techniques for the
analysis of steel-concrete composite beams with partial shear interaction, which include the finite difference
method, the finite element method, the direct stiffness method and the exact analytical model. Both shortand
long-term analyses have been considered in order to provide an indication of how these affect the
accuracy of the predictions. For the implementation of the finite difference method and of the finite element
method, discretisations in both space and time domains are required, while only the time discretisation
needs to be specified for the direct stiffness method and the exact analytical solutions. The time-dependent
behaviour of the concrete has been modelled by means of the age-adjusted effective modulus method
(AEMM) while the remaining materials at the cross-section have been assumed to behave in a linear-elastic
manner. The results obtained using these formulations are qualitatively compared and their accuracy is
estimated adopting the exact analytical model as a benchmark reference with the objective of establishing
the minimum spatial discretisations required to keep the error within an acceptable tolerance. These
comparisons are carried out for simply-supported beams, propped cantilevers and fixed-ended beams, from
which the behaviour of these formulations in the modelling of continuous beams can also be deduced
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