New Approach to Delay Debonding of Steel Plates Externally Fixed to Shear Strengthened RC Beams by using Shear Connectors

Abstract

Strengthening is becoming both environmentally and economically more preferable than replacement. Different types of materials and methods such as sprayed concrete, Ferro-cement, and section enlargement are available for strengthening existing reinforced concrete beams. Strengthening of reinforced concrete beams using external bounded steel plates and FRP strips were both popular in research fields of recent years. Since 1960 researchers reported that attaching steel plates to the sides (web) of a beam, a sufficient increment in the shear capacity can be realized. However, the early debonding of these plated stripes was the most critical failure which leads to prevent reach the full capacity of strengthening required for these reinforced concrete beams. This study presents the efficiency of using new shear connectors to prevent or delay the premature debonding failure of the externally bonded steel plates used for shear strengthening. The experimental program includes four reinforced concrete beams, one as control and three strengthened beams with externally 20 mm width steel plates. The investigation shows that using the new shear connectors were very effective in preventing the premature debonding of the steel plate and therefore enhancing the shear strengthening of the reinforced concrete beams