Abstract
An experimental program was carried out with three reinforced concrete beams subjected to four-point bending tests until failure, where one of the beams had no strengthening (reference), and two were flexurally strengthened with externally bonded passive and prestressed CFRP laminates, where the two strengthened beams were subjected to pre-cracking.
The results showed that passive strengthening leads to an increase in yielding load of up to 8.3% compared to the unstrengthened beam. Also, an increase of up to 23.3% was observed at the ultimate load compared to the reference beam.
However, the use of prestressed strengthening led to an increase of up to 30.7% and 36.0% in the loads at the yielding of the steel reinforcement and at the ultimate load, respectively, compared to the reference beam. The use of prestressed laminate is more effective in increasing the load-carrying capacity of the elements.
Regarding the strains in the strengthening material, considering that the CFRP laminate showed an estimated maximum strain of approximately 14.6‰, an effectiveness of up to 44.4% and 68.4% was obtained for the passive and prestressed strengthening, respectively.
Thus, the ability of the prestressed strengthening system to attain higher strain levels in the strengthening material compared to passive strengthening is highlighted. Furthermore, the use of the prestressed CFRP laminate strengthening system also reduced vertical displacements and pre-existing crack openings in structural elements.
LEIA NA ÍNTEGRA.
Clique Aqui