Static and seismic behaviour of R/C slabs with openings adjacent to columns

This paper presents preliminary results of an experimental campaign dealing with R/C flat slab-column joints with an opening close to the column under combined gravity and seismic loading. A total of six flat slabs (4200 x 1850 x 150 mm) were built and tested until punching failure. The experimental programme consisted of two series, three specimens each, characterized by different positions of the opening with respect to the direction of the seismic loading. In this paper only preliminary results of the first series, named SO1, are shown and discussed. In the first series the opening was located in front of the column face, in the same direction of the horizontal loading (N-S), while in the second series the opening was placed adjacent to the column in the transverse direction (E-W). Two specimens, one for each series, were only subjected to vertical loading without eccentricity, the others were tested under constant vertical loading and cyclic horizontal loading. These tests were performed at the structural laboratory of New Lisbon University, using an innovative test setup designed by one of the authors that allows for the behaviour of a continuous slab in the N-S direction to be simulated. Specimens were connected to two steel columns through 250 x 250 mm steel plates, prestressed against the slab using steel bolts, to ensure monolithic behaviour. Results show how the presence of shear reinforcement increases the maximum horizontal load and the ultimate drift.