Probabilistic Analysis and Non-Linear Semi-Active Base Isolation Spectra for Aseismic Design
Semi-active resetable actuators can significantly improve seismic structural response and customise structural hysteresis loops using novel devices. However, no one has yet examined their use as base isolators despite recent results that show the hysteretic (forcedisplacement) response for optimally controlled base isolation stiffness is similar to a novel 1-3 resetable device response, particularly if including non-ideal, realistic nonlinearities encountered when accounting for non-zero reset times and practical friction. Hence, non-linear semi-active resetable devices should be able to optimally base isolate structures by providing non-linearly increasing resistance to excursions and smooth sliding behaviours with friction back towards equilibrium – matching analytical optimal control results that provide significant isolation and reduce isolated structure acceleration responses. This paper presents the non-linear device models and uses them to analyse semi-active isolated structures over 3 suites of 20 probabilistically scaled ground motions. Results are compared to realistic passive isolation systems and show significant isolation that meets or exceeds passive solutions and closely match optimal isolation results presented in the literature. Overall, this study shows that their may be significant application potential for non-linear semi-active devices in structural isolation.