Moment Redistribution of Continuous Unbounded Post-tensioned High StrengthConcrete Beams Strengthening with CFRP Laminate (Experimental Investigation

The application of fibre reinforced polymer (FRP) materials to the tension side of a prestressed concrete member has been accepted as a strengthening technique to increase the load carrying capacity and in some cases can enhance member serviceability. In continuous concrete beams, ductility allows redistribution of moment between the negative and positive moment zones. Although many in situ post-tensioned concrete beams are of continuous construction, there has been very little research on such beams with external reinforcement. Due to premature debonding failures and the linear stress-strain characteristics of fibre reinforced polymer (FRP) up to failure, the ductility of plated members and their ability to redistribute moment is less than that of un-plated.The present paper describes an experimental investigation of moment redistribution of two-span continuous unbounded post-tensioned high strength concrete, HSC beams strengthened with CFRP plates, in terms of moment redistribution, enhancement of moment and load capacity. Main design variable was area of CFRP laminate in hogging region. To prevent debonding of the CFRP laminates, mechanical anchorages of steel plate and bolts were added to the end of laminates were provided for all of the beam specimens. Various monitoring devices were used to monitor the loading history of the beams. The main results obtained from tests are presented from zero loading up to failure. Increasing the area of CFRP laminates, increased ultimate strength, and decreased ductility, moment redistribution, and ultimate strain on CFRP laminates.

Keywords:

Continuous unbounded post-tensioned beam , HSC , CFRP , Strengthening , Moment redistribution