Motion control of sliding isolated structures

A series of shaking table experiments on control of base motion of sliding structure was carried out for the purpose of validation and improvement of efficiency of use of sliding systems for earthquake hazard mitigation. Addition of controlled friction at the base interface, addition of hysteretic-spring damping and active control were suggested and verified experimentally and analytically. An analytical model based on measured component properties was found suitable to predict the motion of such highly nonlinear interface. Use of a lower friction sliding system produces substantial reduction of the structure deformations and stresses, however this is accompanied by base sways and permanent offsets. This base motion is efficiently corrected by addition of hysteretic-spring damping and by increasing the friction at the interface. Use of an active tendon control helps improving the response of the superstructure with an expense of adding energy.