Influence of lifespan of unbonded prestressed concrete beams on flexurally-strengthening effectiveness of CFRP laminates

Abstract

This paper presents an experimental study on influence of lifespan of beams on flexurally-strengthening effectiveness of CFRP laminates on unbonded prestressed concrete (UPC) beams. The testing program was carried out on eight (08) large-scale UPC T-beams devided in to two groups and conducted in two stages, each group was strengthened with CFRP laminates at different intervals of about 2400 days. The experimental results of the beam group in the first stage were presented
in the authors' published article. In this stage, the experimental results are compared to first stage results and showed that the increase of longterm use led to a decrease in strengthening effectiveness of CFRP laminates, controlling cracking, controlling deflection, and the energy absorption capacity. A new procedure for predicting the flexural resistance of aged UPC beams strengthened with CFRP laminates is proposed with high reliability.

Keywords: Flexural resistance; unbonded prestressed concrete (UPC) beams; lifespan of beams; old structures, CFRP laminates; strengthening