Abstract:
The current seismic design practice for reinforced concrete (RC) walls has been drawn into question following the 2010/2011 Canterbury earthquakes in New Zealand. An overview of two experimental programs currently underway to investigate the seismic behaviour of RC and post-tensioned (PT) walls is presented. The first series of experiments involves cyclic testing of RC walls with minimum vertical reinforcement that performed poorly during the Canterbury earthquakes. Due to height limitations in the laboratory, a test setup was developed to simulate seismic loading on the lower stories of a multi-storey RC wall prototype. The setup included two vertical and one horizontal actuator to simulate the moment, shear, and axial load from the upper part of the wall. The experimental tests will examine the effect of axial load and aspect ratio on the seismic performance of RC walls with minimum vertical reinforcement. The second series of experiments involves dynamic testing of self-centering PT walls that offer a low-damage seismic resisting alternative to traditional RC walls. The structural response of unbonded PT precast concrete wall systems, with and without additional energy dissipating elements, were investigated by means of pseudo-static cyclic, fast cyclic, free vibration, forced vibration, and shake-table testing. These different testing methods were used to investigate the effect of loading type on the dynamic characteristics of the PT wall systems with particular emphasis on the energy dissipated when the wall impacts with the foundation.