Effects of Ratio of CFRP Plate Length to Shear Span and End Anchorage on Flexural Behavior of SCC RC Beams

Abstract

The aim of this experimental investigation is to study the effect of the ratio of carbon fiber-reinforced polymer (CFRP) precured laminate length to shear span and different end plate anchorage systems on the flexural behavior of reinforced concrete (RC) beams cast with self-consolidating concrete (SCC). SCC with a grade of 54 MPa has been used throughout this research to ensure consistent high quality and high concrete compressive strength in all beams and to eliminate the need of any compaction. Ten RC beams strengthened with CFRP plate lengths to shear span ratio of 0, 25, 70, and 85% with and without end anchorages, were tested under monotonic loading. In particular, a single layer of U-wrap sheet and two layers of U-wrap sheets with one layer in the longitudinal direction and the other in the transverse direction were used as end anchorages (double wrap). The results were compared with each other and with those of the same test conducted on an unstrengthened control beam specimen. The load-deflection response of the tested specimens was recorded along with the associated failure modes. In addition, predicted results for the ultimate load capacity computed according to the ACI 440.2R-08 and FIB-TG9.3-01 documents were compared with those of the measured experimental results and other models from the literature. It is concluded from this study that, depending on the ratio of CFRP plate length/shear span and also on end anchorage arrangement, the increase in load capacity of the strengthened beams range from 5% to 80% of the unstrengthened beam. Therefore, the selection of the optimum combination of plate length and end anchorage arrangement can lead to an overall saving in the cost of the strengthening of beams. Other conclusions and observations as related to the effect of CFRP plate length/shear span ratio and end anchorage on ductility and mode of failure were also drawn.