Biaxial pseudodynamic tests of a post-tensioned rocking column with externally mounted energy dissipators

Abstract

The effects of multi-directional loading during earthquake excitation are often overlooked in laboratory experiments due to the high cost and setup complexity. However many structural failures are caused by the combined effect of multi-directional loading. Currently, there is no definitive guidance on the effects of different displacement tracking objectives on the results of multi-directional physical earthquake simulations. This study tested a post-tensioned rectangular rocking concrete column with externally mounted energy dissipators pseudodynamically subjected to simultaneous biaxial loading. The setup emulated bidirectional earthquake ground motion. The study focused on the effects of different displacement tracking strategies in pseudodynamic tests. Experiments found that different displacement tracking strategies gave rise to additional plastic deformations of the specimen and consequently resulted in appreciable differences in the time history predictions both in amplitude and phase lag. Interestingly, the experiments revealed a design deficiency of the externally mounted energy dissipators. The dissipators were shown to be susceptible to buckle during bidirectional loading, a phenomenon that has been missed in previous earthquake simulations.