Performance of reinforced concrete T beams strengthened with flexural CFRP sheets and secured using CFRP splay anchors

Abstract

The use of carbon fiber reinforced polymer (CFRP) anchors has been shown to improve the performance of reinforced concrete (RC) beams strengthened in flexure with CFRP sheets. This improvement results from delaying or controlling the debonding of FRP sheets at failure. In this study, five full-scale T beams were prepared and tested to quantify the flexural enhancement of CFRP anchored beams. The first T-beam was tested as a control beam and the remaining specimens were strengthened with four identical layers of CFRP sheets while applying different splay anchorage arrangements. The second T-beam was anchored with 12 anchors of 16 mm diameter at 140 mm spacing along each shear span. The third T-specimen was secured using 9 anchors of 19 mm diameter positioned at 203 mm spacing per shear span. Four CFRP anchors, with a diameter of 16 mm, were used to secure the CFRP sheets in the fourth T-specimen. These anchors were spaced at 406 mm on center per shear span. The last T-beam was anchored utilizing only one CFRP anchor of 16 mm diameter at the ends of the CFRP sheets. The experimental testing results show that by bonding flexural CFRP sheets with CFRP anchors, the flexural capacity of the RC T-beams significantly improves. This enhancement increases as the number and fiber content of the CFRP anchors increase until attaining the full sectional capacity. Furthermore, the more closely spaced the anchors, the higher the ultimate load level achieved.