الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
There are many problems related to cantilever slabs such as the time-dependent deformation and corrosion problems of steel reinforcement. In addition, lack of experimental studies on the strength of strengthened cantilever slabs. There is an investigation to evaluate the behavior of reinforced concrete cantilever slabs after strengthening with different techniques. Six medium scale specimens, divided into three groups, were tested along a control slab. The first group consists of two specimens which were repaired and strengthened using reinforced concrete jacket above with and without shear connector bars, whereas the second group contained two slabs which were strengthened using two layers of glass fiber reinforced polymer (GFRP) covering 60% and 90% from the cantilever length. The last group involves two specimens strengthened with two steel plates covering 90% of cantilever length. In one specimen, the steel plates were glued to the surface using epoxy resin. The second specimen, the steel plates were affixed to the concrete surface using expansion bolts. The loading was conducted in two phases. Firstly, the samples were subjected to 40% of the ultimate load of the control slab. Secondly, the specimens were reloaded after being strengthened up to failure. The load-deflection, steel strain, concrete strain, failure mode, toughness, and ductility index are presented and discussed in this research. The economic study has been calculated for all slabs. The theoretical analysis for all tested specimens as a method to determine the ultimate load carrying capacity according to Egyptian codes has been calculated. This to determine the effectiveness of the experimental vi results and compare this results with theoretical results of strengthened cantilever slabs. The seven cantilever slabs were modeled using commercial software ANSYS V R15.0. This software is adopted in this study to perform the 3D finite element modeling of specimens. The experimental results revealed that, the jacket strengthening technique has a significant positive influence on all measured responses, regardless of the installation shear connector bars. The GFRP layers strengthening technique showed enhancement the ultimate capacity within range between 17% and 26% compared with control specimen. The strengthening with steel plates glued with epoxy gave higher deflection than all specimens which indicated to better serviceability of cantilever slab. On the other hand, the steel plates affixed with expansion steel bolts showed an economic cost compared with all strengthening systems. There is a good agreement between FE predictions and experimental results.