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Paper 155

Analysis of Steel-Concrete Beams: Influence of Time Dependent Effects, Cracking and Connection Flexibility

R.F. Vieira and F. Virtuoso
Department of Civil Engineering, Architecture and Georesources, Instituto Superior Técnico, Technical University of Lisbon, Portugal

Keywords: steel concrete composite beams, connection, time dependent effects.

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In this paper, the influence of concrete cracking on the stress re-distributions of composite beams with deformable connections is analysed using a numerical model, implementing specific algorithms to deal with the non-linear behaviour. Moreover, the non-linear behaviour of the connection between the steel girder and the concrete flange is also considered.

The influence of time dependent effects, namely the creep and shrinkage of the concrete flange, on the long-term behaviour of steel-concrete continuous beams with a deformable connection is also analysed. This evaluation corresponds to the stress and internal force redistribution together with its time evolution. To this end, the concrete viscoelastic behaviour is considered through an incremental process in time using a numerical method based on the creep approximation with a Dirichlet series.

A numerical model of a composite beam, considering the connection between the concrete slab and the steel girder to be deformable, is adopted for the beam analysis. The finite element is derived from the governing equations of the composite beam with the flexible connection modelled by approximating the internal forces that locally verify the equilibrium in the absence of applied loads. This model is particularly efficient for the analysis of the stress redistribution as a result of the concrete cracking in the hogging regions, when compared with more usual formulations that perform a displacement approximation.