Mass proportional damping in nonlinear time-history analysis

Rayleigh damping is the main form in direct integral method for structural nonlinear dynamic analysis under seismic wave. As stiffness proportional damping usually should be neglected for its significant influence on limit time increment, reasonable mass proportional damping becomes more important in actual engineering. A new form of mass proportional damping has been formulated in form of multi important frequencies and their mode participation coefficients instead of the simplified form which only contains the fundament frequency, and it can simulate the damping system more reasonably than the latter damping model in those complex structures.