Flexural Confinement of Plastic Hinges in Circular Bridge Columns Using Unstressed Prestressing Strand as Transverse Reinforcement

Four concrete columns using prestressing strand as transverse reinforcement were tested to establish design parameters for the use of high-strength transverse reinforcement under seismic loading. Two tests were dynamic. The confinement of flexural hinges was satisfactory at reinforcement levels below that called for by code, provided that the spiral pitch was small enough to prevent buckling of the longitudinal reinforcement. Dynamic loading did not have any unanticipated effect on flexural performance.