Immediate and Long-Term Deflection of Carbon Fiber Reinforced Polymer (CFRP) Concrete Beams

Abstract

This study presents the results of immediate and long-term deflections of reinforced concrete beams strengthened with carbon fiber reinforced polymer (CFRP) laminates under sustained loading The test parameters were sustained load and different degrees of strengthening scheme for both cracked and un-cracked sections of beams. The applied sustained load was 56% and 38% of the ultimate static capacities of the un-strengthened beams for cracked and un-cracked section respectively. The long term deflections of CFRP strengthened beams at six month were on average 1.42 times the immediate deflections for un-cracked beams and 1.45 times the immediate deflections for cracked beams. The experimental results indicate that the long-term deflection of cracked beam shows significantly higher value compared to that of un-cracked beams. A comparison of time dependent deformation between analytical and experimental results shows closer agreement for the un-cracked beam sections. More conservative theoretical estimation is observed in the case of cracked beam section in spite the inclusion of tension stiffening effect. Finally, factors affecting the long-term deflection of strengthened beams are discussed to get better understanding on the long term behaviour of strengthened beams.