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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 81
PROCEEDINGS OF THE TENTH INTERNATIONAL CONFERENCE ON CIVIL, STRUCTURAL AND ENVIRONMENTAL ENGINEERING COMPUTING
Edited by: B.H.V. Topping
Paper 36

Finite Element Modelling of Steel-Concrete Composite Beams Subjected to Uniformly Distributed Loads

F.D. Queiroz+, P.C.G.S. Vellasco* and D.A. Nethercot+

+Department of Civil and Environmental Engineering, Imperial College London, United Kingdom
*Structural Engineering Department, State University of Rio de Janeiro, Rio de Janeiro, Brazil

Full Bibliographic Reference for this paper
F.D. Queiroz, P.C.G.S. Vellasco, D.A. Nethercot, "Finite Element Modelling of Steel-Concrete Composite Beams Subjected to Uniformly Distributed Loads", in B.H.V. Topping, (Editor), "Proceedings of the Tenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 36, 2005. doi:10.4203/ccp.81.36
Keywords: composite beams, finite element method, uniformly distributed load, parametric analysis, load-deflection behaviour, shear connectors.

Summary
The design of multi-storey buildings utilising composite floors often involves cases where solid slabs are subjected to uniformly distributed loads. Although very common in practice, the numerical modelling of the response of the beam under these loads is not a straightforward process, particularly when all the material nonlinearities are taken into account.

This paper presents a nonlinear three-dimensional finite element model for composite beams subjected to uniformly distributed loads based on the use of the ANSYS software [1]. The model incorporates two alternatives for the distribution of shear connectors: the conventional uniform and a triangular spacing scheme where the stud distribution follows the nominal elastic shear diagram. The finite element model is able to predict the full flexural response of the composite beams, including the load-deflection behaviour and associated failure modes for either slab crushing or stud failure. The accuracy and reliability of the model are demonstrated by comparisons with experiments [2] and to alternative numerical analyses [3,4].

This paper discussed several numerical modelling issues related to convergence problems that arise when the concrete material is considered, loading strategies for the simulation of distributed loads and a comparison between the load control and the displacement control methods in terms of computer efficiency. Aspects related to force convergence criterion and multi-frame restart analysis using ANSYS were also analysed. Finally, the results of an extensive parametric analysis using the calibrated finite element model are presented. This parametric study concentrates on the influence of variations in the concrete and steel material properties on the structural behaviour of uniformly loaded composite beams.

It was observed that, for a fixed concrete strength, and increasing either the yield stress of the flanges or the yield stress of the web, the corresponding load-deflection curve becomes stiffer. For the range of material properties considered in the parametric analysis, the change in the load-deflection curve was more significant for the cases in which the web yield stress was increased. Moreover, it was noticed that, for a fixed combination of yield stresses for the flanges and web, and increasing the concrete strength, the failure mode of the composite beam can change from slab crushing to stud failure.

References
1
Swanson Analysis Systems, ANSYS Theory Reference. Seventh Edition, Swanson Analysis Systems, s.1., s.d. Online Manual, version 7.0
2
Chapman, J.C. and Balakrishnan, S., "Experiments on composite beams", The Structural Engineer, 42(11), 369-383, 1964.
3
El-Lobody, E., Lam, D., "Finite element analysis of steel-concrete composite girders", Advances in Structural Engineering, 6(4), 267-281, 2003. doi:10.1260/136943303322771655
4
Gattesco, N., "Analytical modelling of nonlinear behaviour of composite beams with deformable connection", Journal of Constructional Steel Research, 52, 195-218, 1999. doi:10.1016/S0143-974X(99)00026-7

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