Effect of Different Confinement Shapes on the Behaviour of Reinforced HSC Beams

High strength concrete (HSC) provides high strength but lower ductility compared to normal strength concrete. This low ductility limits the benefit of using HSC in building safestructures. This means that a designer should be aware of limiting the amount of tensilereinforcement to prevent the brittle failure of concrete. Therefore the full potential of the use of steel reinforcement cannot be achieved. This paper presents a method to prevent the brittle failure of concrete beams. Five beams made of HSC were cast and tested. The cross section of the beams was 200×300 mm, with a length of 4 m and a clear span of 3.6 m subjected to four-point loading, with emphasis placed on the midspan deflection. The first beam served as a reference beam. The remaining beams had different tensile reinforcement and the confinement shapes were changed to gauge their effectiveness in improving the strength and ductility of the beams. The compressive strength of the concrete was 85 MPa and the tensile strength of the steel was 500 MPa and for the stirrups was 250 MPa. Results of testing the five beams proved that placing helixes with the right diameter and pitch in the compression zone of reinforced concrete beams improve their strength and ductility.