EFFECT OF REINFORCEMENT ON PUNCHING SHEAR BEHAVIOR OF FLAT SLABS

Flat slabs systems are massively used in multi-story buildings because of their savings in story height and construction time, as well as for their flexibility in architectural remodeling. However, they frequently suffer brittle punching-shear failure around columns when subjected to gravity and lateral loads. Thus, punching is one of the most important phenomena to be considered during the design of reinforced concrete flat slabs. An experimental testing is the best way to study the performance of the failure of different structural elements. The present study includes experimental of the punching behavior of shear reinforced square simply supported flat slabs. The experimental work is constructed tested in the Cairo structures laboratory in the department of civil engineering at the Cairo University. This research goal is investigating some construction alternatives to enhance flat slab strength, ductility, and deformability. The alternatives are: adding different types of punching shear reinforcement, using closed stirrups, open stirrups, and bent bars. The benefits of using punching shear reinforcement are reducing slab thickness, cost, and weight of structure. This study is carried out to investigate the behavior of 12 flat slab specimens having average concrete strength about of 35 MPa subjected to a concentric compressive load. The slab dimensions are the same for all twelve specimens, (1100 x 1100 x 120) mm, with a square column dimensions equal to (150 x 150 x 400) mm at the center of slab. The ratio of flexural reinforcement is 2.22% to ensure obtaining punching failure before flexural failure. During testing, ultimate capacity, steel strain, cracking pattern and deformation are recorded. The experimental results are analyzed and compared against values estimated from different design codes.