18. Theory and Applications of the 3-DOF Modal System for PBSE of Asymmetrical Buildings

Seismic evaluation plays an important role in performance based seismic engineering (PBSE). The modal system is the basis of structural dynamics, which is closely associated with PBSE. This paper shows that the modal system is not necessary to be a single-degree-of-freedom oscillator. Actually, a modal system with three degrees of freedom is even more suitable for representing a single vibration mode of two-way asymmetrical buildings . The proposed three-degree-of-freedom modal system has many advantages of seismic evaluation for inelastic or non-proportionally damped asymmetrical buildings . Furthermore, from the proposed modal system, a novel tuned mass damper has been developed for the modal control of asymmetrical buildings . The study results show that the novel tuned mass damper is effective in reducing two translational and one rotational displacements simultaneously.