Tests of reinforced concrete beams strengthened with wire rope units

This paper presents a simple unbonded-type shear strengthening procedure for reinforced concrete structures with wire rope units. Fifteen beams were tested to failure in shear, repaired, strengthened using the proposed wire rope units, and then retested. The main variables investigated were the shear span-to-depth ratio, and the prestressing force, orientation and spacing of wire rope units. The shear strength of beams strengthened with wire rope units increased relative to that of the corresponding original beams. Reinforced concrete beams strengthened with inclined wire rope units exhibited higher shear strength than those with vertical wire rope units. It was also observed that the higher the initial prestressing force in the wire rope units, the higher the shear strength gained. The principal tensile stress in concrete decreases with the increase of the prestressing force in wire rope, as a result, the diagonal tensile cracking strength of strengthened beams was higher than that of the corresponding original beams. The validity of using ACI 318-05 and EC 2 shear provisions to predict the shear capacity of strengthened beams was examined. The shear capacity of strengthened beams having shear span-to-depth ratios below 2.5 is reasonably predicted using the ACI 318-05 formula. On the other hand, EC 2 overestimates the shear transfer capacity of wire rope units for beams having shear span-to-depth ratios above 2.5.