الفهرس 
Chapter 2 Literature ReviewOnly 14 pages are availabe for public view
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Abstract
Failure of flat slabs due to punching is very interested subject. The main objective of this research is to study experimentally, analytically and numerically the effectiveness of the proposed external strengthening techniques to resist punching shear of reinforced concrete flat slabs. The used external strengthening techniques were: (1) external DROP panel confined with GFRP sheets, (2) external steel shear studs (Bolts) at different distances (at half slab effective depth and at the slab effective depth from column face), (3) external GFRP stirrups, at different distances (at half slab effective depth and at the slab effective depth), and (4) external GFRP sheet in the tension side. Experimental and numerical programs were carried out to study different external strengthening techniques to resist punching shear of reinforced concrete flat slabs. The experimental program contained of seven square slab specimens (1700 x 1700 x 150 mm) with circular column (stub) had 250 mm diameter at its center. The tested specimens are intended to simulate, half scale interior-slab-column connection. All specimens tested as simply supported slabs under one-point static loading at the center of the column. The numerical program was carried out using ANSYS V.19 program as nonlinear finite element software program to study the effect of some parameters. Calibration and verification of ANSYS V. 19 has been done by comparing the results of the load deflection curves, cracks and ultimate loads with the experimental ones. Strengthened slabs using two rows of external GFRP stirrups on circles at distances half the slab effective depth and at the slab effective depth from the column face is the beast method which increase the ultimate load and the cross ponding deflection, displacement ductility, initial stiffness, crack stiffness and toughness by 87 % ,78 %, 9 %, 7.8%, 16.5% and 116% respectively compared to the unstrengthen slab. The results showed that both ECP 203-2018 and ACI 318-19 building codes are conservative compared to the results the experimental program.
Some variables not studied experimentally were studied numerically which included the effect of concrete compressive strength, reinforcing steel yield strength, slab thickness, shear studs diameter, shear studs spacing, shear studs distances from the column face, main steel ratio/max, secondary steel ratio/ max, DROP panel thickness and DROP panel diameter.