Seismic Behaviors of High-Strength RC Columns under High Axial Loads

Seismic Behaviors of High-Strength RC Columns under High Axial Loads

In this paper, five full-scale high-strength RC columns were tested to assess interstory drift capacities under high axial force of 0.6 ' Ag fc . A prescribed amount of confined reinforcements meeting the ACI 318 Code requirements was also designed for all specimens. But an upper limitation of 700 MPa stipulated by ACI design code for the confined reinforcements was used instead of their design yield stress. There were a total of five full-scale square columns of 600 x 600 mm tested at the MATS facility of the National Center for Research on Earthquake Engineering(NCREE), Taiwan. Concrete strengths of 70 MPa for Specimens B1, B3 and B5 and 100 MPa for Specimens B2 and B4 were used. All specimens adopted reinforcement grades of SD685 for main bars and SD785 for transverse stirrups and ties. The confined reinforcement details, including spacing, number of ties in each level, and end bent degree of the tie hooks, were elucidated as well.