Flexure retrofitting of ribbed one-way reinforced concrete slabs through external reinforcing bars

The paper reports results of physical tests on three different ribbed slab typologies, extensively utilized in Italy in the 60’s. The use of lightweight ribbed one-way Reinforced Concrete slabs is quite common in Italy and southern Europe, especially in residential buildings where they allow for a reduced self weight in comparison with a whole concrete section having similar bearing capacity, resulting in a lower seismic action. As many of those structures nowadays do not satisfy the requirements of the new building codes, both at ultimate (ULS) and service (SLE) conditions, the behavior of a slab before or after strengthening was compared toward the evaluation of the efficiency of the strengthening technique, in terms of increase in the post-cracking stiffness, ductility and bearing capacity. The proposed technique results a valuable and promising methodology for an effective strengthening of ribbed slabs.