Compressive Toughness Characterization of Normal and High-Strength Fiber Concrete Reinforced With Steel Spirals

Abstract

Steel, polyolefin and carbon fiber reinforced concretes were combined with traditional transverse steel reinforcement in the form of steel spirals. The complete stress-strain relationship and the ductility of the concrete in compression in both the unconfined and confined states was evaluated. The compressive toughness was evaluated both according to the Japanese Standard JSCE - SP% and according to a new method proposed in the present work. The experimental program consisted of testing concrete cylinders under compression at two different strength levels: normal (48 MPa) and high strength (70 MPa), reinforced with different volume percentages of steel, polyolefin and carbon fibers. These tests were then repeated with the addition of spiral reinforcement with different pitches (25 and 50 mm). It was found that by combining fibers and steel spirals it is possible: (1) to obtain a high level of fracture energy dissipation, which could previously be obtained only by using a high volume percentage of spiral steel; and (2) to improve the maximum strain of the concrete, corresponding to the first failure of the spiral steel.