Experimental tests for the analysis of the load-bearing capacity of an internal slab-column connection after its punching at various positions of the column

Normally, in practice the situation of a slab-column structure is rarely analyzed after the occurrence of a local breakdown. Catastrophes which have happened so far indicate the need of considering in detail slab-column connections in reinforced concrete structures in order to prevent progressive collapses. Some suggestions concerning the prevention of such situations are to be found merely in CSA A23.3-04 [2] and ACI 318 [1]. This problem is not dealt with in the Polish Standards, nor in the Eurocodes. The paper presents the results of investigations performed on a model of slab-column connections in the scale 1:1. Three variants of the position of the column in relation to the centre of the slab have been considered: the axial position, the position in an unidirectional eccentricity, and in bidirectional eccentricity. The tests were performed in two phases, viz. "Phase 1" preceding the punching and "Phase II" after punching to the complete destruction of the connection. The aim of these investigations was to find out how far any additional bending moment resulting from the eccentric effect of the load affects the value of the destructive load imposed on the connection after its punching. The obtained results permitted to determine the relations between the exerted load and the displacement of the column in time, and also to determine the values of the force at which the rupture of the bars above the column had taken place. The results of these tests were compared with the standard.