Investigation of vertical reinforcement termination in lightly reinforced concrete walls

Abstract

Reinforced concrete (RC) structural walls are effective lateral force-resisting components commonly implemented in tall buildings. Recent studies have investigated the impact of minimum vertical reinforcement limits on the ductility at the plastic hinge region of RC walls and resulted in revisions to design standard requirements in both New Zealand and the United States. These studies focused on cantilever walls with a single plastic hinge at the wall base, whereas tall buildings exhibit more distributed plasticity demands up the wall height. In addition, the termination rules for the vertical reinforcement in the plastic hinge region were not considered during previous tests and modelling. The main objective of this research is to investigate the seismic performance of RC walls in tall buildings, considering the influence of the vertical reinforcement contents up the full wall height. Push-over analyses were conducted on a 20-storey tall RC wall prototype, to investigate the sensitivity of the termination height of the vertical reinforcement in the plastic hinge. Based on the model results, current capacity design rules reviewed in NZS 3101:2006 may be insufficient to ensure that yielding is confined to the plastic hinge region. Preliminary recommendations are made regarding the termination height of additional vertical reinforcement within the plastic hinge.