Finite element analysis of local buckling of steel-concrete continuous composite beams (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.
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.
The Baltic Journal of Road and Bridge Engineering, 2010
The present paper is concerned with the elastic design optimisation of continuous composite beams. This optimisation is based on the analysis of the beam in the inelastic range including the concrete creep and shrinkage, the tension stiffening and temperature difference effects as well as the possible local buckling instability. The finite element program PONTMIXTE (adapted to study continuous beams at real scale with short time computation) is first presented with its different sections: Pre-design (in accordance with Eurocode specifications), Non linear finite element calculation and Post-processing. In order to validate the proposed model, the numerical calculations are compared against experimental results from tests on a two-span beam in reduced scale (7.5 m length for each span) without taking into account the local buckling phenomenon avoided in the experimental test by using web-stiffeners. Next, special attention is paid to study the influence of the local buckling instability on the internal moment redistribution coefficient between hogging and sagging zones. The application concerns different 3-span beams of bridge at real scale with medium span lengths (40-60-40 m). The post-buckling behaviour represented by moment-rotation curves (M-θ) is deduced from a 3D finite element model of the cross-section developed using Castem finite element code. The M-θ curves describing the local buckling phenomenon are approximated using hyperbolic functions and implemented in PONTMIXTE using a specific rotational spring finite element. The influence of this instability on the moment redistribution coefficients calls the Standart predictions into question.
Study on Behaviour of Steel Concrete Composite Beams
Zenodo (CERN European Organization for Nuclear Research), 2022
Steel concrete composite beams (SCCB) are widely used nowadays in offshore bridges and highrise buildings because of their high span to depth ratio, high strength, ductility, light weight and rapidity in construction. SCCB consists of concrete slab and steel beam connected by shear connectors. It is an important compositional structure in prefabricated construction. In SCCB the concrete slab provides compressive strength and steel beam provides tensile strength. The behaviour of SCCB mainly depend on type of loading applied on the structure, environmental conditions etc. Bridges and industrial structures in general, are commonly subjected to cyclic loading of vehicles or operating machines. So, the behaviors study on composite structures under fatigue is essential. The structural elements in SCCB is subjected to local buckling or Lateral Distortional Buckling (LDB). This made it important to study the stability behaviour of SCCB. Stainless steel-concrete composite beam has been regarded as a new application that is widely used by engineering community. The benefits brought by stainless steel, such as superior corrosion and fire resistance, high strength and ductility as well as improved durability, could offer optimal and sustainable solutions for infrastructures and highways. This study is focussed on the behaviour of SCCB under cyclic loading, bending, shear, combined bending and shear and also on stability aspects.
Journal of Constructional Steel Research, 2012
In the hogging bending moment region, continuous composite beams are subjected to the ultimate limit state of lateral-torsional buckling, which depends on web stiffness as well as concrete slab and shear connection stiffnesses. These three stiffnesses compose the rotational stiffness of composite beams. Eurocode 4 defines this stiffness in composite beams with plane webs, but there are no conclusive studies on the stiffness of composite beams with sinusoidal-web profiles. This paper presents a formulation to evaluate the rotational stiffness of composite beams with sinusoidal-web steel profiles presented based on (a) test results for four representative prototypes of the inverted U-frame model, (b) the development and calibration of a numerical model using the ANSYS commercial finite element software, and (c) the computational processing of sixty-eight numerical models. In these models, the researchers attempted to vary all the parameters that could influence the rotational stiffness, such as web height and thickness, slab size and type (concrete or composite), number of shear connectors in the cross-section and longitudinal spacing of connectors.
Moment Redistribution in Continuous Steel-Concrete Composite Beams with Compact Cross Section
Journal of Structural Engineering, 2010
The paper investigates the design of continuous steel-concrete composite beams with compact cross section using the elastic analysis with limited redistribution. The permissible moment redistribution which satisfies the requirements of the ultimate limit state ͑collapse͒ and serviceability limit state ͑crack width in the concrete slab͒ was computed. An advanced finite element program accounting for all mechanical nonlinearities and time-dependent phenomena ͑creep and shrinkage of concrete͒ was used. An extensive parametric analysis aimed to determine the influence of several geometrical parameters on the permissible moment redistribution was carried out on propped cantilevers and fixed-end beams. The analyzed parameters include the shape of the steel profile, the ratio between the depths of concrete slab and steel beam, the steel to concrete area ratio, and the reinforcement percentage of the concrete slab. The analysis was limited to compact steel sections ͑AISC 360-05͒ or class 1 steel sections ͑Eurocode 3͒ and low ductility reinforcing steel ͑elongation at maximum load ru = 2.5%͒. The moment redistribution domain which satisfies the rotation compatibility in the critical sections, due to the attainment of the rupture of the reinforcement or the local buckling of the steel profile, and the control of cracking ͑Ͻ0.3 mm͒ in service was evaluated and compared with the limits recommended by current codes of practice. A proposal for the allowable moment redistribution domain according to the limits of the study was given.
SHEAR AND MOMENT BEHAVIOR 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.
2017
The present paper is concerned with the elastic des ign optimisation of continuous composite beams. This optimisation is based on the analysis o f the beam in the inelastic range including the con crete creep and shrinkage, the tension stiffening and tem perature difference effects as well as the possible local buckling instability. The finite element program “P ontmixte” (adapted to study continuous beams at rea l scale with short time computation) is first presented wit h i s different sections: Pre-design (in accordance with Eurocode specifications), Non linear finite element (FE) calculation and Post-processing. In order to valid the proposed model, the numerical results are compared to xperimental test ones on the example of a twinspan beam in reduced scale (7.5m length for each span) w ithout taking into account the local buckling phenomenon avoided in the experimental test by usin g web-stiffeners. After that, special attention is paid to study the influence of the local buck...
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...