Structural Behavior of Recycled Aggregate Concrete Continuous Beam with Hybrid Reinforcement under Monotonic and Repeated Load

This paper investigates the Structural behavior of recycled aggregate concrete continuous beam with hybrid reinforcement under monotonic and repeated loads.The experimental work includes testing 15 continuous beams, two specimens without recycled aggregate, and other beams cast with recycled aggregate.One specimen with recycled aggregate containing steel fiber was treated as a reference for specimens reinforced with FRP.Three specimens were cast with 20%, 40%, and 70% replacement ratios of recycled aggregate.GFRP, CFRP, and BFRP reinforced the other three specimens, containing 40% recycled aggregate and 1% steel fiber volume fraction.Three specimens were reinforced with hybrid reinforcement (steel and FRP bar), including 40% recycled aggregate and steel fiber.The last three beams were reinforced with hybrid reinforcement and tested under repeated load.The specimens' dimensions are 225mm in depth, 150mm in width, and 3000mm in length, consisting of two equal spans of 1400mm for each span.The test variables are the replacement ratio of recycled aggregate, changing the reinforcement type, loading form, and adding steel fiber.The test results showed that using recycled aggregate led to a slight decrease in ultimate load up to 5.38%.Using steel fiber led to an increase in the ultimate load by up to 10%.All specimens with recycled aggregate and reinforced with FRP bars showed a decrease in ultimate load by up to 47%.Using hybrid reinforcement led to an increase in ultimate load up to 53.8%.The specimens tested under repeated load showed a decrease in ultimate load by up to 15%.