9625979 Nagarajaiah This project was submitted to the "Structural Control for Performance, Safety and Hazard Mitigation Research" competition. The work centers on the development of variable stiffness structural systems using a novel semi active continuous variable stiffness (SACVS) device which varies the structural stiffness and frequency continuously and smoothly, without inducing impulsive forces and maintaining nonresonant state under seismic and wind excitation. The main objectives of the project are: to characterize the non-linear dynamics of the combined linear structure and nonlinear-SACVS device by developing analytical models and calibrating these models experimentally; to develop control algorithms based on intelligent control strategies such as neural networks; to perform shake table testing of the SAVCS device in a structural system; and to evaluate the effectiveness of the SACVS system by comparing its controlled and uncontrolled response, and as compared to a fully active system. Results from this research will contribute to the development of innovative semi-active continuous variable stiffness systems and their application to structural control which will require less power to operate and will overcome limitations of existing control systems. ***
