Behavior Under Repeated Loading of RC Beams Externally Strengthened in Flexure with SRG Systems

Steel-reinforced grout (SRG) systems are effective methods for the flexural strengthening of reinforced concrete (RC) beams. In this study, the effect of a limited number of repeated loads on the structural response and debonding evolution of strengthened beams was experimentally investigated. The number of available research concerning the cyclic behavior of SRG-strengthened members is quite limited and this research attempts to cover this knowledge. A total of ten full-scale RC beam specimens were tested under a four-point bending scheme. The effectiveness of the traditional externally bonded (EB) strengthening technique was compared with a promising innovative technique referred to as inhibiting/repairing/strengthening (IRS). The test variables included the use of two SRG configurations using high and low steel strip density. The experimental results revealed that the performance of the beams was largely dependent on the spacing of the steel strands within the reinforcing strip. Under repeated loading, the debonding of the external system takes place when steel fiber with high mass per unit of area was used. By increasing the matrix impregnation of the steel strip, the composite system was not affected by debonding. Further, the efficiency in terms of flexure enhancement, local and global ductility performance and energy dissipation of the beams are also discussed.