Performance evaluation of existing isolated buildings with supplemental passive pseudo-negative stiffness devices

A new configuration for passive pseudo-negative stiffness device (PPNSD) is proposed to work as a supplemental device for the seismic protection of existing isolated buildings. The proposed PPNSD reproduces the hysteretic behaviors of semi-active pseudo-negative stiffness devices (PNSD). Using the ratchet-pawl mechanism, a prototype was realized and tested under cyclic loading, validating the feasibility of the proposed PPNSD. Seismic reduction effect of the PPNSD on single-degree-of-freedom (SDOF) systems was verified through seismic response analysis. The PPNSD shows superiority in suppressing the peak acceleration response of long period structures, which is unlikely to be achieved even with large supplemental damping. Then, the performance of isolated buildings with PPNSD was evaluated in comparison to those of isolated buildings with traditional passive isolators under far-field (FF), near-fault pulse-like (NFP), and near-fault non-pulse-like (NFNP) ground motions. It is shown that the use of PPNSD not only simultaneously reduced the base drift and the acceleration of superstructures, but also was effective for all the FF, NFNP, and NFP motions.