Seismic performance of concrete columns with inadequate transverse reinforcement
Existing New Zealand building stock contains a significant number of structures designed prior to 1995 with inadequate detailing of the internal or ‘gravity’ reinforced concrete (RC) columns. Typically these columns have insufficient transverse reinforcement, lap-splices in the plastic hinge region, and longitudinal bars that are ‘cranked’ at the end of the lap-splice. Columns with such details have been shown to perform poorly when subjected to seismic actions, losing shear and axial load carrying capacity at low levels of drift. A set of displacement based models are presented (and verified experimentally) for the shear failure and subsequent loss of axial capacity for these columns under both uni- and bi-directional bending.