A real-time structural parameter modification (RSPM) approach for random vibration reduction: part I, principle

Earthquake-induced structural vibrations are stochastic in nature. Part I of this study presents a novel structural control methodology for earthquake vibration reductions. It summarizes the efforts of the authors toward the development of RSPM control between 1993 and 1996. The operating control principle is minimization of conservative energy. The control hierarchy is realized by low-power-consuming devices (functional switches) with multiple ranked loops. The control method is to adjust optimally the physical parameters (mass, damping and stiffness) of the structure in real time. This method is therefore described as real-time structural parameter modification (RSPM). It may be called variable passive control or parametric control. The basic thesis of RSPM is presented, together with a discussion of the minimal principle of conservative energy of a vibrating system and the RSPM control hierarchy which contains four ranked loops. Variable passive control is capable of handling the stochastic nature of earthquake ground motion and it does not have certain major drawbacks of conventional active control methods. Part II of this study will describe the experimental verifications of RSPM. It will be shown that RSPM can dissipate considerably more energy than existing passive energy dissipation devices. In addition, RSPM can reduce vibrations resulting from multi-directional excitations.