EARTHQUAKE INPUT ENERGY SPRCTRUM FOR INELASTIC SDOF SYSTEMS

The earthquake input energy spectrum for inelastic single degree of freedom (SDOF) systems with various damping ratio and ductility factor subjected to 40 earthquake records of 4 site types is studied. The influence of parameters, including the damping ratio and ductility factor of SDOF systems and the intensity of ground motions, on the input energy spectrum is investigated. The results indicate that the peak value of the input energy spectrum mainly depends on the intensity of ground motion, damping ratio and ductility factor. In the long period range, input energy spectrum increases with damping ratio and decreases with ductility factor. With the normalized input energy spectrum method, the input energy spectrum is simplified into three portions as a function of the vibration period of the SDOF systems. Finally, based on statistical analysis of the normalized spectrum, the parameters of the input energy spectrum are suggested.