Proposed Design of High-Strength Spiral Reinforcement in Compression Members

Current provisions of the ACI 318 Code and AASHTO Design Specification limit the nominal yield stress of spiral reinforcement for compression members to 414 MPa (60 ksi). A procedure for the design of high-strength spiral reinforcement for compression members is proposed and evaluated. The proposed method utilizes usable stress values, rather than nominal yield stress values, for spiral design. The research included large-scale axial load tests on 14 spirally reinforced concrete compression members with spiral reinforcement yield stress values ranging from 538 to 1345 MPa (78 to 195 ksi) and usable stress values ranging from 545 to 1131 MPa (79 to 164 ksi). It was found that, for the compression member geometries and material properties treated in this study, the proposed design procedure satisfactorily predicted the behavior of the compression members made from spirals with usable stress values up to 758 MPa (110 ksi).