الفهرس 
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Abstract
Retrofitting of reinforced concrete elements with fibre reinforced polymers, FRP, wraps is considered one of the techniques used successfully for the last few years. Previous investigations were concerned with the behaviour of rectangular RC columns strengthened by FRP wraps under axial loading.Consequently, a comprehensive study of the different parameters affecting the seiamic behaviour of RC columns is vitally needed. the objectives of this research are to carry out an experimental investigation to study the behaviour of rectangular RC columns wrapped with FRP sheets under cyclic lateral and axial loading. The main parameters investigated in this research are: volumetric ratio of FRP, spacing between FRP layers, different anchorage sysyems, axial load level,type of FRP sheets and the aspect ratio of columns. Eleven large-scale RC columns with different dimensions were tested under both cyclic lateral and contant axial loading.The specimens were detailed to carry gravity loads only without any precautions for seismic loading.
The experimental results showed that the as-bulit RC column with low percentage of steel hoops and not designed or detailed according to any seismic code was easily damaged, performed poorly under seismic loads and failed with a brittle shear mode. Confinement of rectangular RC columns with FRP wrapping improved the seismic performance and increased both of the strength and ductility of such columns. All the retrofitted columns failed in a ductile flexural mode without any shear cracks.
In the analytical study, the modeling of the columns was carried out using the computer program IDARC which was developed in the university of New York at Buffalo and modified for analysis of RC elements retrofittted with FRP. The modified program gave acceptable results comparing with the experimental results. In addition, a simplified approach, based on a developed numerical computer program.