Experimental investigation on flexural behaviour of vertically-curved circular-hollow steel sections strengthened with externally bonded carbon fibre reinforced polymer

•Behavior of vertically curved steel circular hollow sections strengthened with CFRP was experimentally studied.•An analytical study is proposed to calculate elastic deflection of CFRP strengthened vertically curved hollow sections.•Length of the CFRP wrapping drastically change the ultimate load capacity of vertically curved beam.•The highest ultimate load was obtained when the ratio between CFRP length to total length of the beam become 0.625.•Failure modes of CFRP strengthened beams were also depended on the CFRP wrapping length. The behaviour of Carbon Fibre Reinforced Polymer (CFRP) strengthened vertically curved beams of Steel Circular Hollow Sections (SCHS) was studied. Sixteen numbers of curved beams with 1200 mm span having four radii of curvatures; 0 mm, 2000 mm, 4000 mm and 6000 mm were tested under three-point bending tests. A range of CFRP lengths up to 1000 mm was selected. The maximum performance was noted when the ratio between CFRP length to total length of beams is 0.625. Four types of failure modes were observed in the strengthened beams. A theoretical model was also developed and validated to predict the load–deflection behaviour of CFRP strengthened tubular vertically curved beams in the elastic region using the Maxwell-Mohr integral method.