Influence of steel fibres on punching shear strength of flat slabs self compacting concrete

Flat slabs are the slab without beam so it save level of the floor. The punching shear caused failure around the column area under applied load on the column, to reduce this failure shear reinforcement were used but it is not easy practically especially for low slab thickness, it can be used steel fibres in the concrete mix to increase the punching shear strength. The aim of the research to study the punching shear of flat slab of self compacting concrete ,this type of concrete used widely because it is environmental friendly. The main parameters are the reinforcement of the slab, two percent were taken with different volume percent of steel fibre (0,0.4,0.8,1.2)%.The main results obtained that the punching shear strength increased with the volume percent of fiber and steel reinforcement, it increased about 27.95% , 21.4% for slabs with reinforcement ratio =1.4%, =1.8% respectively for 1.2% fibre, and the energy absorption increased about 107% for slab with 1.2% fibre and =1.8% compared with slab without fibre. The results show also increased in ductility as the fibre content increase and the failure perimeter of the slabs is approximately circular shape and the failure perimeter increase as the fibre content increased. :ملتسأ 28 – 6 2013 :لبق 13 – 10 2013 Al-Rafidain Engineering Vol.22 No. 4 May 2014