UCLA

Buildings are vulnerable to earthquake ground motions. To help reduce the loss from earthquake events, seismic protective devices emerged in recent decades to improve the performance of building structures against earthquake loads. The ultimate goal of this research is to explore new devices and/or optimally design existing devices to better protect buildings such that the total cost (both direct and indirect) due to earthquake damages can be reduced to a minimum level. This is accomplished through the following research tasks:

First, this study established accurate numerical nonlinear models for different building systems so that their seismic performances can be calculated realistically including nonlinear behavior. The numerical models are validated by comparing simulated building performances with that of the shaking table test data of a full-scale building. Using these validated numerical models, the peak inelastic drift ratio and permanent residual drift ratio are evaluated and correlated with building performances.

Second, this research assembles a collection of practical seismic protective devices for buildings and their numerical models. The emerging trend of seismic control devices with adaptive stiffness and damping properties under different loading scenarios yet still remain largely passive is explored. In particular, a novel negative stiffness device is investigated along with two other seismic protective devices, namely the base isolation and nonlinear damping device through dimensional analysis. In addition, numerical modeling schemes of the these devices as well as well as the self-centering device are implemented.

Third, the proposed research intends to enable performance-based implementation of seismic protective devices that can logically take into account of the complexities, uncertainties and variability involved with the seismic responses of buildings. A comprehensive performance index depicting the total loss of the system has been invented to evaluate the building performance. In addition, the optimal range of design parameters of base isolation system for building systems is provided under the performance-based earthquake engineering framework.