EXPERIMENTAL STUDY ON THE GRAVITY SHEAR EFFECT ON THE PUNCHING SHEAR BEHAVIOUR OF RC SLAB-COLUMN CONNECTIONS UNDER SEISMIC LOADING

Reinforced concrete flat-slab structures are widely used because of their practicality. However, this type of structures can be subjected to punching-shear failure within the slab-column connections. Without shear reinforcement, the slab-column connection can undergo brittle punching failure, especially when the structure is subjected to lateral loading in seismic zones. This research is a part of an experimental investigation about the punching shear behaviour of interior RC slab-column connections under seismic loading. The main objective is to discuss the effect of the gravity shear level on the punching shear behaviour[1]. The current paper represents only the results of the first four tested specimens without shear reinforcement. The first specimen was tested subjected to vertical gravity load only without cyclic loading while the other three specimens were tested under dif erent vertical load V which was kept constant during testing in addition to a reversed displacement controlled cyclic loading which was increased up to punching shear failure. The gravity load V was chosen as 0.4,0.6 and 0.8 Vo respectively, where Vo is the vertical load causing punching shear failure according to ACI31814[2]. All tested specimens have the same slab dimensions of 2000x2000mm, slab thickness of 200mm, flexural reinforcement ratio of 1.62% and the same column dimensions 250mmx250mm. Finally, the experimental results are analyzed and compared to international codes such as American Code ACI318-14 and Euro Code EC2-2004[3]. In light of these results, some preliminary conclusions are presented.