Global stability analysis in reinforced concrete buildings with transfer beams

Abstract

The influence of the presence of transfer beams on the global stability of symmetric and asymmetric reinforced concrete buildings was analysed through the global stability coefficient γz and the P–Δ method. Various combinations of structural models were considered (with many or few transfer beams, positioning the beams in the centre or at the ends of the building, with asymmetry in X and Y directions and symmetric models). According to their size and numerical proportions, the transfer beams were observed to either contribute or not to the improvement of the building's stability and to the decrease or increase of displacements. Asymmetries may stiffen a frame in the sense that they increase the inertia of the structure, but they cause a torsion effect whose magnitude depends on the side of the building to which wind is applied. In addition, the presence of asymmetries causes an increase in the global stability coefficient, producing a reduction in the structure's rigidity. When the transfer beams enabled a small ratio between the deformation and the span, an increase in global stability was observed, especially in the opposite direction to the axis of the beams.