Snap-back Testing for Characterizing Dynamic behavior of Precast Rocking Columns

The procedure for this experiment consists of constructing a single reinforced concrete column, and offsetting the column by an initial angular displacement, and measuring the free-rocking motion of the column once released. The test setup will have a mass that will be able to be set at different positions on the rocking column. This will result in changes to the dynamic properties of the system, and changes to the time history response. By changing the dynamic properties of the system, correlations between what affects the response of a rocking system can be drawn based upon which parameters where changed and by how much. Also, another set of tests will be conducted using externally mounted #5 steel bars as hysteretic dampers allowing about 14% energy dissipation in the system. The goals of these experiments will be to gain a better understanding of the energy dissipation mechanisms operating within rocking structures, and to be able to accurately predict the free rocking motion of a controlled rocking structure. Although these experiments will aid in better predicting the time history of controlled rocking structures, it will also be a valuable trial run for much more expensive shake table testing. The specimen dimensions and testing protocol for these tests have been made to match that of a scaled down version of the PreWEC system that will be tested dynamically in this project.