Strengthening of Reinforced Concrete Beams with Circular Opening at Flexure Zone by Various Types of Fiber Reinforced Polymer

Abstract

This paper aims to investigate the flexural behaviour of reinforced concrete (RC) beams containing circular opening at mid-beam span and strengthened using externally bonded Textile Reinforced Concrete (TRC) sheets, Carbon Fibre Reinforced Polymer (CFRP) sheets and Carbon Fibre Reinforced Polymer (CFRP) plates. The flexural behaviour including ultimate load, deflection, crack pattern as well as failure mode was investigated. Five RC beams with the dimensions of 1700 mm length and cross section of 200 mm x 250 mm with design concrete strength of 64 N/mm2 were tested under 4-points loading. The tested RC beams consists of solid beam as a control beam, unstrengthened RC beam with circular opening and strengthened RC beams with circular opening. The circular opening with ratio of 0.32 is classified as small opening with diameter of 80 mm was kept constant for all beam specimens. The inclusions of circular opening at the middle of beam span slightly decreased the ultimate load of beam about 6.2% compared to control beam. The reduction of stiffness was also experienced in RC beam with opening. The application of strengthening in beams with circular openings manages to regain the beam capacity about 17.5 to 22.6% higher than the unstrengthened RC beams with opening.