Improving multi-axial hybrid testing capability to replicate earthquake actions on structures

Abstract

This report presents the results from an experimental programme aimed to improve the pseudodynamic testing method for simulating earthquake loads on structural specimens. Specific extension of the research included developing advanced multiple actuators control to simulate multiaxial and coupled earthquake excitations. A low-damage rocking concrete column was selected as the experimental specimen and was tested pseudostatically and pseudodynamically. This allowed multiple tests on the same specimen. A sophisticated algorithm precisely applied the loads to the top of the column in two orthogonal directions through two computer controlled actuators. An additional novelty of the research was the examination of the effects of different displacement patterns and loading sequences on the column response, and the corresponding implications for laboratory testing procedures on design. Pseudostatic test results showed that different loading patterns indeed produced
very different strength prediction as well as different energy dissipation characteristics. This confirmed the need to consider and intelligently select appropriate loading protocols in laboratory test, to replicate structural behaviour expected during actual seismic events. This project also found that different loading sequences within loading substeps in a pseudodynamic test can lead to different displacement responses from identical earthquake input.