SEISMIC-ENERGY DISSIPATION IN MDOF STRUCTURES

The seismic input energy imparted to a structure is dissipated by hysteretic behavior and other nonyielding mechanisms usually represented by equivalent viscous damping. It is generally recognized that there is a strong correlation between the energy dissipated by hysteretic action and the seismically induced level of damage. While viscous damping has a small effect on the amount of energy imparted to a structure, it has a significant influence on the amount of hysteretic energy dissipation. A parametric study is presented on the influence of the mathematical modeling of viscous damping on seismic-energy dissipation of multidegree-of-freedom (MDOF) structures. The damping is modeled using mass-proportional, stiffness-proportional, and Rayleigh damping computed from either the initial elastic or the tangent inelastic system properties. Various structural performance indices are evaluated for bilinear hysteresis model of simple MDOF structures with different strength levels, strain hardening ratios, and damping ratios.