DETERIORATED CONCRETE COLUMNS STRENGTHENED WITH FRP COMPOSITE REINFORCEMENTS

摘要

Many concrete structures over the world have deteriorated through the corrosion of steel reinforcement. In concrete columns, corrosion often occurs preferentially on one side of the member, leading to unsymmetrical loss of steel area. The focus of the present investigation is to study the strengthening of deteriorated concrete columns with fiber reinforced plastic (FRP) composite sheets. Using steel reinforcements with reduced cross sections, concrete columns are cast to represent members with corroded steel bars. Both circular and rectangular columns will be tested. Some columns are wrapped with FRP composite along the hoop direction alone, while others are strengthened with FRP in both the hoop and vertical directions. This paper mainly focuses on results for circular columns, while some results on rectangular columns are also described. A simple model is proposed to compute the failure load of the strengthened columns from concrete and steel properties and reasonable agreement can be obtained. For circular columns, as expected, vertical FRP reinforcements are not particularly effective. However, for rectangular columns, where confinement has little effect on ultimate strength, preliminary results indicate good potential of strengthening with vertical FRP reinforcements.