Flexural capacity of the CFRP prestressed concrete slabs subjected to sustained & fatigue loading

The behaviour of concrete slabs with prestressed carbon fibre reinforced polymer (CFRP) composite bars is investigated in this paper. The main advantage of CFRP bars is their high strength/self-weight ratio. On the other hand, Young's modulus is lower compared to steel reinforcement which is the main cause for large deflections. To eliminate such deflections and to utilize high tensile strength of CFRP bars it is extremely useful to prestress the bars. During the experimental work a set of fifteen 4.5-metre-long concrete slabs were casted. Each slab was prestressed with five CFRP bars. Eight slabs were subjected to static - four point bending test. Six slabs were subjected to fatigue and one slab was subjected to sustained loading for one year. The load-deflection diagram of a CFRP prestressed slab is traditionally bi-linear up to the rupture of the prestressed CFRP bars. It was verified experimentally that high-cycle fatigue has no significant effect on the flexural capacity of the slab. The long-term investigation showed suitable behaviour of CFRP prestressed slab under heavy sustained load.