Effects of trapezoidal cross-section dimensions on the behaviours of CFRP SCC beams

Abstract

This study investigates the behaviour of trapezoidal cross-sections self-compacting reinforced concrete beams under flexural failure, with and without strengthening with carbon fibre reinforced polymer CFRP. The studied beams were divided into two groups according to their cross-sections; each group included five beams, and the first group (T 20 ) were those with trapezoidal cross-sections with dimensions length 1,600 × height 260 × width of 160 mm at the bottom and 200 mm at the top, while second group (T 24 ) consisted of those with trapezoidal cross-sections with dimensions length 1,600 × height 260 × width of 160 mm at the bottom and 240 mm at the top. The experimental programme included studying the effects of top width on the flexural behaviour of beams with trapezoidal cross-sections, in addition to studying the effect of reinforcing those beams with varying numbers, locations, and methods of placement of CFRP strips. The experimental results showed that trapezoidal cross-sections with 240 mm top width gave higher ultimate load capacity by 4 to 11.54%, as well as offering lower deflection, compared to trapezoidal cross-sections with 200 mm top width. In addition, strengthening beams with CFRP strips leads to an increase in the ultimate load capacity by 4 to 24% in trapezoidal cross-section beams, reducing their deflection and delaying the appearance of the first crack in the concrete. It was found that applying CFRP strips to the maximum moment region increased the ultimate load capacity by an average of 4.17 to 7.7 % in comparison to beams strengthened with strips applied along the beam.