Reinforced concrete flat slab with opening under lateral loading

Reinforced concrete flat-slabs have been extensively used in the last decades thanks to shorter construction time and minimal structural depth. However, under gravity loading the reduced thickness provides high stresses in proximity of columns that could induce the punching failure of the flat-slab. Furthermore, for combined gravity and lateral loading the slab-column joint exhibits a very brittle behaviour against horizontal drift due to premature failure caused by punching. This paper deals with the behaviour of slab-column connections in presence of an opening close to the column, under combined gravity and seismic loading. In a previous work the authors presented the preliminary results of a new experimental campaign characterized by different positions of the opening with respect to the direction of the seismic loading. In this paper those results are discussed and compared with results achieved without opening. Tests were performed at the structural laboratory of New Lisbon University. Results show how the presence of the opening provide a detrimental effect in the response of the slab-column connection under vertical loading, while under seismic actions the presence of the opening is less affecting the slab response.