الفهرس 
Acknowle dgment
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Abstract
ABSTRACT
In recent years, there has been an increased interest in strengthening and repairing of existing concrete structures, and this process requires a vast monetary investment. Therefore, today there is a need to find an appropriate and economical method to strength and to repair existing concrete structures. This study attempts to understand the shear behavior of reinforced concrete (R.C) beams externally strengthened with Near Surface Mounted (NSM) pre-tensioned steel bars. Twelve reinforced concrete beams of cross-section 150 mm width, 300 mm overall thickness and total span length 1400 mm were fabricated and tested using three point load test. One of these was fabricated without strengthening while the others were repaired to study the effect of damage levels, pre-tensioning levels, binder groove filler, and spacing of NSM pre-stressed bars on shear behavior of the repaired R.C beams. The results showed that the effectiveness of the proposed technique is achieved in both ultimate and serviceability limit state. NSM pre-stressed bars could reduce the effect of the existing cracks and increase the beams capacities. Also, the mode of failure of the repaired beam changed from brittle failure to ductile failure.