Influence of the location of the column on the load capacity of a slab-column connection for the inner column after punching

Abstract

Normally in practice the situation of a slab-column structure is rarely analyzed after the occurrence of a local breakdown. According to the regulations quoted in CSA A23.3 an adequately calculated bottom reinforcement crossing above the column may be applied preventing a further development of the catastrophe. Instructions concerning such a structure are also contained in ACI 318 [1]. The paper presents the results of investigations carried out on model of slab-column connections in the scale 1:1. 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. Three variants of the position of the column in relation to the centre of the slab have been considered: the axial position, the position on a unidirectional eccentricity, and on 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. Basing on these tests the results were compared with the standard, and it turned out that the cross-section of the reinforcement had been underestimated. Thus, it ought to be suggests that in the calculations the value of the ratio of the destructive force imposed on the column to the destructive load should be increased.