الفهرس 
Tensioning Against External Reaction FrameOnly 14 pages are availabe for public view
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Abstract
Strengthening and retrofitting of existing reinforced concrete (RC) structures have been always required due to deterioration for various reasons. The main aim of strengthening is either to increase the load carrying capacity and/or to enhance the serviceability limit states of RC members. Fiber reinforced polymers (FRP) have been widely used in strengthening of RC members due to their excellent mechanical properties such as high strength-to-weight ratio and its corrosion free characteristics, which make them durable and substantial for strengthening applications. Strengthening of RC flexure members with non-prestressed FRP laminate has a negligible effect on the serviceability limit states due to the low stiffness of the bonded FRP laminates.
The use of external prestressing in strengthening applications is gaining popularity according to its advantages in controlling cracks and deflection induced in structural elements. Hence, prestressing of carbon FRP (CFRP) laminates prior to bonding is considered an innovative solution to enhance the overall performance of concrete members.
Behavior of RC simply supported members strengthened in flexure with externally bonded (EB) prestressed CFRP laminates have been addressed in previous researches. These researches studied the efficiency of prestressed CFRP laminates in enhancing the flexural capacity and serviceability limit states and illustrated the effect of CFRP prestressing level on ductility and failure modes of strengthened members. On the other hand, strengthening of indeterminate concrete members in flexure with EB prestressed CFRP laminates should be addressed to investigate the moment redistribution and the effect of secondary moment on the overall strength in addition to its general deformational behavior.
This research investigates the flexural behavior of RC two span slabs strengthened with EB prestressed CFRP laminates. The purpose of this study is to investigate the contribution of different strengthening schemes in the slabs load carrying capacity, deflection, moment redistribution and ductility. Five full scale RC slabs were prepared and cast at the Housing and Building National Research Center (HBRC). A special prestressing system was used for prestressing the CFRP laminate. Strengthening of slabs occurred at test location to simulate the field applications. The slabs were statically tested in flexure by two vertical point loads at each span up to failure. The obtained results showed an increase in the load carrying capacity and stiffness of tested slabs up to 53 and 40%, respectively. Different details of the prestressing technique as well as the performance of different prestressing schemes are discussed in this thesis.