Evaluation of the deflection of steel-concrete composite beams at serviceability limit state

The paper investigates the response of steel–concrete composite beams at serviceability limit state. Both cases of propped and unpropped steel beam during the pouring of the concrete slab were considered. The maximum vertical displacements in the short- and long-term were evaluated for simply supported and continuous composite beams using accurate finite element models. The numerical results were compared with the maximum displacements obtained using the simplified approach suggested by the Eurocode 4. This formulation which, in the case of continuous beams, accounts for the nonlinear behavior of the component materials, was found to be often non-conservative. On the basis of the outcomes of an extensive parametric analysis, a simple design criterion was proposed. This method is based on the limitation of stresses in the steel profile below the yield limit, and on the use of a simple relationship to account for the connection flexibility. The proposed procedure to calculate maximum displacements of composite beams provides conservative results, with a level of accuracy suitable for practical design.

► The paper investigates steel-concrete composite beams at serviceability limit state.
► Propped and unpropped simply supported and continuous composite beams are considered.
► A simplified formulation (Eurocode 4) is compared with FE numerical solutions.
► A simple yet conservative design criterion to evaluate the deflections is proposed.
► Deflections evaluated according to the proposed procedure are always conservative.