Reinforced Concrete Beam with Openings Strengthen Using CFRP Sheet

Abstract

Reinforced concrete is widely used in numerous parts of buildings, like columns, beams, and slabs. The material contains concrete that provides great compression strength, while steel reinforcement embedded in concrete has great tension strength. Recently, reinforced concrete beams with openings increasingly used worldwide due to the request of the building’s owner to provide utilities and architectural requirements. Based on previous research, reinforced concrete beams with openings reduce the stiffness around the openings, reduce the strength, and may change the pattern of failure of the beam. The failure of reinforced concrete beams with openings mainly located around the openings. Therefore, strengthening around the opening is required to increase the strength of the beam. Many options can be used to strengthen beams. In this study, Carbon Fiber Reinforced Polymer (CFRP) sheets are chosen. CFRP are composite materials that consist of carbon fiber with a resin to create material that has higher performance properties compared to each material separated. CFRP is a type of reinforcement that has several applications in industries, for example, strengthening reinforced concrete structures. CFRP sheet provides superiority compared to steel-reinforced concrete that is still used, such as durability and reliability of the materials.  This research objected to acknowledging the pattern of failure of reinforced concrete beams using finite element modeling software in some cases, like reinforced concrete beams without any opening, reinforced concrete beams with one circular opening in the shear zone without any strengthening, reinforced concrete beams with two circular openings in the shear zone without any strengthening, reinforced concrete beams with one circular opening strengthened using CFRP sheet, and reinforced concrete beams with two circular openings strengthened using CFRP sheets. From this study, beam with circular opening strengthened using CFRP have increase of 16.00% and the beam with 2 openings is increasing by 35.00%. The crack pattern of the beam without an opening is concentrated in the mid-span of the beam with a flexural failure, while the other specimen has a shear failure within circular openings. Significant improvements in ultimate load conclude that using CFRP sheet to strengthen beam with circular openings are suitable.