METHODS OF STRENGTHENING OF COMPOSITE AND REINFORCED CONCRETE COLUMNS BUILDINGS AND STRUCTURES UNDER RECONSTRUCTION

Abstract

The given article deals with experimental research of composite and reinforced concrete columns strengthened by external steel reinforcement. To evaluate the load-carrying capacity of reinforced concrete beams with externally bonded steel plate, the influence of the bonded steel plates to the soffit on the shear strength of the beams, and the effect of shear strengthening using wing-type side steel plates for stocky concrete beams (broad and low web) have been examined. From the results, it was found that the shear strength is properly evaluated by shear capacity equations for non-plated reinforced concrete beams unless a crack develops at the edge of the steel plate, and that the side plate bonding is likely to have a potential to be effective in strengthening for the stocky beams without stirrup. Additionally, loading tests using two 75-year-old deteriorated reinforced concrete beams with adhesively bonded steel plates to the soffit were carried out. The bonded steel plates no longer contributed to the load carrying capacity after the joints between the steel plates failed due to debonding.

Using the handlay-uptechnique, successive layers of a woven fiberglass fabric were bonded along the shear span to increase the shear capacity and to avoid catastrophic premature failure modes. The strengthened beams were fabricated with no web reinforcement to explore the efficiency of the proposed strengthening technique using the results of control beams with closed stirrups as a web reinforcement.