Self-balanced earthquake simulator on centrifuge and dynamic performance verification

Abstract

This paper describes some details of a self-balanced earthquake simulator on the centrifuge in KAIST and results of a series of proof tests for verifying its dynamic performance and excitation capacity. The main feature of the earthquake simulator is the dynamic self-balancing technique adopted to eliminate a large portion of the undesired reaction forces and vibrations transmitted to the centrifuge main body. This feature is achieved by embarking counter-weight platform and two back-to-back hydraulic bearings. The maximum base shaking acceleration of the earthquake simulator is 20 g in horizontal direction under 40 g of centrifuge acceleration with a maximum payload of 700 kg, corresponding to 0.5 g of horizontal shaking acceleration in the prototype scale. The loading frequency ranges from 40 Hz to 200 Hz (300 Hz) for sinusoidal (real earthquake) inputs. The dimension of slip table is 670 mm x 670 m in length and width. The proof test results show that the earthquake simulator can reproduce mono-frequency sinusoidal inputs in a wide band of frequencies as well as multi-frequency real earthquake inputs at the bottom of soil models with satisfactory fidelity, and the dynamic self-balancing contributes to the safety of the centrifuge structure.