Untersuchungen zum Tragstoß von nachträglich mit Ortbeton ergänzten zweiachsig gespannten Stahlbeton-Fertigteilplatten

Prefabricated concrete slabs are about 5–6 cm thick and contain the required reinforcement for bending in both directions as well as the optional reinforcement for shear. These slab elements are put together on site with an in-situ concrete topping. The two-way precast floor slab requires an overlapping of the load-carrying reinforcement in both directions, which is specified by Eurocode 2 and the general technical approval documents of the lattice girder that is used. These specifications limit e.g. the permitted rod diameter, the cross-sectional area of the reinforcement and the permitted shear force within the joint. These are based on experimental testing of precast concrete walls where lattice girders are used as well.
The aim of the experimental and numerical tests that were carried out was to question the current regulations for overlapping joints. The application of the permitted rod diameter, cross-sectional area of the reinforcement and the distance between the lattice girders, in particular, are considered while exploring this issue in order to be able to relax the current specifications. The numerical studies consider the experimental analysed specimen. For this, they use an initial damage of the interface between the concrete cast and the in-situ layer as well as a self-developed approach of the tensile post behaviour of the concrete. The parametric study is using this validated concrete model. Based on this study, new recommendations for the overlapping joint of the load carrying reinforcement are given.