EXPERIMENTAL INVESTIGATION OF THE DYNAMIC PERFORMANCES OF THE L.E.D.A. SHAKING TABLES SYSTEM

The Laboratory of Earthquake engineering and Dynamic Analysis (L.E.D.A.) has been recently completed at Kore University of Enna. The Research Institute includes several laboratories operating in the fields of civil engineering and structural dynamics. The most important research facility of the Experimental Dynamics section is a system of two 6-DOFs 4 m by 4 m shaking tables. Thanks to the TRIO Sistemi e Misure RT3-3V control system, the tables can be used both separately and simultaneously in order to simulate the effects of earthquakes on large span buildings and on structures subjected to asynchronous ground motions (e.g. bridge girders, industrial buildings). Moreover, seismic tests on small and large scale models, qualification of innovative control devices for earthquake protections, as well as vibration analyses on large equipment and mechanical systems can be performed. Shaking table tests strongly depend on the capability of the control system to reproduce the desired artificial accelerations and to accurately replicate the input signals. The distortion between the desired and the reproduced signal depends on several factors among which the whole physical system parameters (reaction mass, actuators, valves) and the dynamic characteristics of the specimen under test. In this paper, the experimental results on the earthquake signals tracking performance of the LEDA shaking tables are presented. Tests are performed according to different system configurations: single table with a rigid payload equal to 40 t, single table with a twostorey 1:2 scale steel frame structure and two unconnected tables during synchronous motion with rigid payload equal to 22.2 t. These tests are conducted to evaluate the accuracy and fidelity of the shaking table control settings in signal reproduction.