Proposed design of high-strength spiral reinforcement in compression members

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