repair and strengthening of reinforced concrete beams using fiber reinforced concrete

Experimental investigation on the structural behavior of repaired and strengthened defected beams using U-shape jacket of fiber reinforced concrete was carried out as a traditional proposed technique. The main intention of the present work is to examine the capability of two different repair and strengthening methods through two groups. The effect of the presence of steel fiber, with Vf =1%, number and diameter of additional stirrups and effect of converting the rectangular section to T- section on the structural behavior was also investigated. The experimental results of load-deflection behavior were compared with the analytical prediction. Finally, a comparative study with previous methods using steel or fiber reinforced plastic plates (FRP) bonding techniques of repair and strengthening of beams was performed. The results of the present work applying the proposed method for the first group support the following conclusions: A positive effect to the presence of stirrups and steel fibers in the new concrete jacket was recorded. A high composite action and good confinement were produced with increasing the number and area of stirrups in the concrete jacket and with using steel fiber reinforced concrete. This conflicted to the recorded enhancement in both stiffness, cracking and ultimate loads of the upgraded beams. In the last stages of loading the presence of stirrups in the adding concrete layer play a role in enhancing the composite action of the strengthened beam and so increased the final stiffness. The results showed that upgrading RC beams using 9 f 10 mm stirrups in the added U-jacket reached by the ultimate load to that of the reference beam irrespective of the surface condition between the old and the new concrete.