Limited ductility design of reinforced concrete columns.

This report describes an experimental and analytical investigation of the strength and ductility of reinforced concrete columns. Four columns of square cross-section were tested under axial compression loading and cyclic lateral loading applied at mid-height which simulated seismic loading. The main variable investigated was the quantity of transverse confining steel used, which ranged between 17 to 46 percent of the NZS 3101:1982 recommended quantity for ductile detailing. The experimental results are reported in the form of lateral loaddisplacement and lateral load-curvatures hysteresis loops, curvature profiles, transverse steel strain distributions and concrete compressive strains. The results are discussed and compared with the analytical predictions. A modified equation for the quantity of confining reinforcement in rectangular columns is recommended. Conclusions are made regarding the ductility available from columns containing substantially less transverse confining reinforcement than recommended by the New Zealand concrete design code