STRENGTHENING OF REINFORCED CONCRETE SLABS USING EXTERNAL PRESTRESSED FIBER REINFORCED POLYMERS

Abstract

Nowadays, many existing reinforced concrete structures need structural repair and strengthening in order to keep the minimum performance requirements or to increase its performance due to new loads. Fiber Reinforced Polymers (FRP) have immerged as strengthening systems due to their advantages when compared to conventional steel. Although the use of non-prestressed FRP laminates in strengthening of flexure members has a significant effect on increasing the load carrying capacity, strengthening with FRP laminate has a negligible effect on the serviceability limit states due to the low stiffness of the FRP laminates. Moreover, using non-prestressed FRP laminates limit the utilization of the full strength of FRP materials due to the premature bond failure of the laminates. External prestressing has long been recognized as an effective means of strengthening existing concrete structures. This is due to the better performance of the concrete members under service loading conditions and high capacity of the externally prestressed members. However, the lack of data regarding the durability of externally prestressed concrete elements can be considered as the main obstacle for wide use of this system. Strengthening with externally prestressed FRP laminates combines the benefits of excellent durability and structural improvement in terms of serviceability and ultimate limit states. Behavior of reinforced concrete (RC) structures strengthened with externally bonded non- prestressed FRP laminates, have been improved and addressed in previous researches, but strengthening using externally bonded