Flexural behavior of prestressed CFRP reinforced concrete beams by two different tensioning methods

摘要

Expansive concrete beams reinforced with symmetrical CFRP enclosure and conventional concrete beams strengthened with prestressed CFRP sheets both have been proven superior to non-prestressed concrete beams in certain flexural aspects. In this study, it aims to investigate the flexural behavior of prestressed CFRP reinforced concrete beams by two different tensioning methods, which are CFRP enclosure on expansive concrete beams and pretentioned CFRP strengthened concrete beams. Ten beams were fabricated in total. The prestress in both the concrete and CFRP, cracking load, ultimate load, load-midspan deflection curves, load-maximum crack width curves of these beams in two methods were compared. The expansive volume of the expansive concrete, the utilization ratio of CFRP and cracking details were also discussed in this paper. A new analytical model has been proposed in this study for calculating the cracking load of both concrete beams and the ultimate load of the expansive concrete beams. Results indicate that, compared with pretentioned CFRP strengthened concrete beams, CFRP enclosed expansive concrete beams exhibited higher cracking load but lower ultimate load. It also shows that the theoretical predictions of the ultimate loads by the proposed model are in good agreement with experimental results for both types of beams.