Rotational stiffness of continuous composite beams with sinusoidal-web profiles for lateral-torsional buckling (original) (raw)
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Engineering Structures, 2016
Lateral-torsional buckling (LTB) is an ultimate limit state that can occur in the hogging moment regions of continuous composite steel and concrete beams. This limit state is characterised by the buckling of the steel profile compressed flange (bottom flange) about the minor axis, together with a distortion of the steel profile web. The European Standard EN 1994-1-1:2004 provides an approximate procedure for LTB design that is applicable to continuous composite beams, but only those with a plane web steel profile. The most important step of this procedure is the determination of the elastic critical moment. In this paper, a finite element analysis (FEA) model was developed using the software ANSYS to determine the elastic critical moments of continuous composite steel and concrete beams with corrugated sinusoidalweb steel profiles, which were evaluated against numerical data from the literature. Ultimately, a study involving 45 models was conducted based on FEA modelling, and a procedure for predicting the elastic critical moment of composite beams with sinusoidal-web steel profiles was proposed.
In continuous or semi-continuous steel-concrete composite beams, subjected to hogging bending, the laterally unrestrained bottom flange of the steel I-section of the composite beam is under compression, therefore is sensitive to a restrained distortional buckling phenomenon. Distortional buckling check of plain webbed composite beams is relatively well researched and the buckling strength criteria are introduced to design codes. Eurocode 4 design criterion is based on the inverted U-frame model, and the buckling strength reduction factor is calculated in the same way as in the case of lateral-torsional buckling. The criterion is expressed in terms of the composite section bending moment resistance, so that it does not take into account the effect of inelastic moment redistribution in statically indeterminate composite beams. The present paper focuses on the review of current practice in the evaluation of distortional buckling strength of composite beams, suggests some improvements allowing for the extension of this practice, and summarizes the authors' investigations and proposals for practical check of distortional buckling strength of plain-webbed and castellated composite beams.
Experimental behaviour of composite beams subjected to a hogging moment
Steel and Composite Structures
The present work addresses the rotational capacity of steel-concrete composite beams, which is a key issue for the seismic design of composite frames. Several experimental tests from the literature are summarised, and the effects of various parameters on the available plastic rotation are discussed. Furthermore, a number of remarks are made regarding the need for supplementary experimental results. The authors carried out experimental tests on four composite beams in which the type, width and connection degree of the slab were varied. During the tests, the deflection and strains in the steel profiles and bars were measured and recorded, wherein the observed trends in the measured parameters indicated that the failure mode of the beam was influenced by global and local buckling. A comparison of the experimental results to the theoretical ultimate strengths and moment-curvature relationships confirms that buckling phenomena occurred after section yielding, even if a consistent plastic...
Finite element analysis of local buckling of steel-concrete continuous composite beams
2016
For continuous steel-concrete composite beam with the slab rests directly on the metal profile, in negative moment, an important part of the web is subject to compressive stresses, hence the buckling limiting the ability of rotation of the cross section, thus preventing to reach its ultimate strength. An analytic model calculation, based on a failure mechanism, to evaluate with sufficient precision the rotation capacity to the right of the intermediate support depending on the moment evolution, has been developed by (Tehami 1997) and justified by experimental results of tests carried out by the same author at INSA Rennes (France) and its confrontation with other models proposed in the literature. In the present work we investigated, using a numerical method based on finite element, the proposed model by reference (Tehami 1997) on the local buckling of steel-concrete continuous composite beams. Indeed, and in an effort to learn more about the phenomenon of local buckling of steel-concrete continuous composite beams, a finite element analysis was performed on this model (Tehami 1997) using the ABAQUS code. Then this work focuses on numerical simulation, based on different modeling assumptions in order to obtain moment-rotation relationship. A comparison with previous work found in the literature was made.
2013
The use of steel-concrete composite framed buildings is particularly efficient for their high lateral stiffness, strength and ductility; therefore the structural performance achievable with these systems makes them particularly suitable for applications in seismic zone. However the current state of technical knowledge concerning the characterization of the structural behavior of steel-concrete composite systems subjected to seismic actions is not exhaustive and requires additional theoretical and experimental studies in order to better understand their behavior and improve the design procedures. Often these shortcomings mean that the choice of the framed structure as seismic resistant systems falls in reinforced concrete or steel buildings. In fact, in the case of the steel-concrete composite framed structures the complexity of the problem is increased by the identification of the role of the connection between the reinforced concrete component and the steel one. In light of this as...
The effects of axial tension on the hogging-moment regions of composite beams
Journal of Constructional Steel Research, 2012
Structural parts commonly comprised of composite members such as bridge approaches, inclined parking ramps and stadium beams, can be subjected to a combination of high axial loads and bending moments. Steelconcrete composite construction is a popular solution for these types of structures due to the numerous advantages that they offer. Although, current design codes (e.g. Eurocode 4, American code AISC, Australian codes AS2327 and AS5100) provide rules for the design of composite columns subjected to flexure and axial load, however the design of composite beams, which are asymmetric in nature under the combined effects of tension and bending, is not yet fully addressed. This paper investigates the ultimate strength of composite beams under the combined effects of axial tension and negative (hogging) bending moment. An experimental programme carried out in the laboratory of the University of Western Sydney comprised of a total of six specimens representing composite beams and subjected to various levels of axial tension and bending moment. Ultimate failure modes were identified and the resulting interaction diagrams were compared to the results of sectional rigid plastic analysis. Following the tests, three-dimensional finite element models were employed using the ABAQUS finite element software to further investigate the nonlinear behaviour of the composite beams and extend the experimental observations by studying the effects of parameters such as the span length and the effect of partial shear connection. Finally, simple design rules and formulae are proposed for use in engineering practice.
The 2011 World Congress on Advances in Structural Engineering and Mechanics (ASEM11+), 2011
A three-dimensional finite element model for geometrically nonlinear analysis of semicontinuous composite steel-concrete beams was presented using the commercial software ABAQUS. The investigation focuses on the determination of their flexural and rotational capacities with the influence of full and partial shear connection. From the investigation, the finite element model is able to simulate the overall flexural behaviour of the composite steelconcrete beams subjected to concentrated load for example the load-deflection behaviour, longitudinal slip at the steel-concrete interface and failure modes. The model was validated by comparisons with experiments.
Behaviour and design of composite beams under bending and axial tension
7th International Conference on Advances in Steel Structures, 2012
Steel-concrete composite structural systems are widely used in modern construction due to their numerous advantages in terms of economy and efficiency. There are many situations where composite beams are subjected to a combination of bending moment, axial loads and shear forces. Nevertheless, the design of composite beams under combined actions is not yet fully covered by the current codes of practice. This paper describes a series of experiments conducted in the University of Western Sydney in order to investigate the ultimate flexural strength of composite beams when subjected to simultaneous axial forces. Twelve composite beams were tested under both sagging and hogging bending moments and the moment-axial force interaction curves were identified. Following the tests, advanced finite element models were established in order to simulate the nonlinear behaviour of the specimens and the accuracy of the numerical methods were assessed against the available experimental data. The model was then used to carry out parametric studies and to cover a series of beam sizes and spans used in practice. The effect of partial shear connection and its implications to the design were also considered. It was found that the flexural capacity of composite beams is considerably deteriorated when a high axial load acts in the steel beam. This deterioration in flexural strength follows different rules in hogging and sagging bending regions. Based on the experimental results and the finite element analyses, design interaction curves were constructed and simple design models are proposed for use in engineering practice
Latin American Journal of Solids and Structures, 2020
Composite alveolar beams consist in the union of two structural systems largely employed in civil construction sector: the steel-concrete composite beams and the alveolar steel beams. Thus, its use allows their advantages to be enhanced, enabling to design even larger spans and to achieve more economical and sustainable solutions. Considering that Brazilian and international standards do not directly specify criteria for the analysis and design of these beams, in this paper it is presented the development and validation of an updated finite element model, using ANSYS software, capable of simulating different failure modes that may occur, such as web-post buckling, Vierendeel mechanism and flexural mechanism. The obtained results presented a good correlation with experimental results from previous works. After the model validation, the effect of the openings on the composite beam was investigated and discussed, and it was concluded that the web-post buckling may limit the structural gains on load capacity, so it is important to adopt opening patterns that enhance the resistance of the beam to this mode of failure.