الفهرس 
Experimental investigation of the effect of top, middle, and bottom mesh reinforcement ratioat different concrete strengths on the punching shear capacity of R.C. flat slabs
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Abstract
Reinforced concrete flat slabs supported on columns are common in residential and commercial buildings. The main disadvantage of this system is its possible brittle mode of failure due to punching shear stresses at the vicinity of columns. The capacity of this connection between slab and column depends on several factors like concrete strength, flexural reinforcement, slab thickness and column aspect ratio. Building codes predict the nominal shear strength considering some of these factors and disregarding others. In this experimental study, sixteen test slabs (120x120x12.5) cm were cast and tested in the Properties and Strength of Materials Laboratory in the Department of Civil Engineering {u2013} Cairo University. The investigated parameters were: concrete compressive strength, flexural reinforcement ratio, compression reinforcement ratio, and additional Mid-Thick reinforcement mesh ratio. The results demonstrated that the punching shear strength increased by about 42% when the concrete strength changed from 33MPa to 63MPa and increased by 31.5% as the main reinforcement ratio increased from 1% to 2.83%. The results also indicated that The Egyptian code (ECP-203-2007) and the American code (ACI-318-14) are underestimating the punching shear strength by more than 50%, due to disregarding the effect of flexural reinforcement ratio