Repair of Damaged Strip and Stirrup Confined Beam Column Joints Using Carbon Fiber Reinforced Polymer

Abstract

The performance of column-beam joints has been recognized as an important factor since long affecting the overall behavior of reinforced framed structures subjected to large scale lateral loading during earthquakes. Different repairing techniques are being used to retrofit column-beam joints weakened by seismic excitations. This study is a part of ongoing research to develop efficient retrofitting techniques. As a part of research work, twelve pre-damaged specimens were repaired. The specimens were divided into two majors group based on strength. The characteristics compressive strength of first group was 28 MPa and that for the second was 21 MPa. Each group was further divided into three sub-groups numbered one, two and three, and designated as conventionally reinforced concrete joint CRCJ, strip confined joint SRCJ and strip confined beam. Group one was consisting of Grade 40, 10 mm diameter bar as stirrups. In group two and group three steel strips was used as stirrups. Gage of group two strip was 14 and that of group three was 18. The total area of stirrups remained constant which was 0.11 mm2. The basic idea behind using the strips as stirrups was to check the performance of strips as stirrups in order to avoid congesting of steel bars at joint. Cracks in the sample were filled with epoxy resins and joints were repaired with CFRP laminates.