DEMAND OF INPUT ENERGY FOR SDOF SYSTEM BASED ON THE WENCHUAN EARTHQUAKE

112 recordings within 150km to causative fault surface during the Wenchuan earthquake are used to establish a database. The influences of rupture distance, site conditions, duration of ground motion, effects of hanging wall and footwall, and directivity effect on elastic input energy are investigated based on the energy responses of SDOF (single degree of freedom) structure. Within rupture distance 30km, the structural input energy should be approved due to the amplified peak of acceleration. A softer the site condition leads to a higher input energy. The characteristic period corresponding to the peak of input energy spectra is not moved to the right due to site effects. The peak of input energy spectra is affected by the duration of ground motion, and it increases as the duration of ground motion increasing. In the near-fault regions, footwall effect and directivity effect have strongly impact upon the input energy of structure for a given period. When rupture distance is larger than 30km, higher input energy on footwall are demanded in the range of medium and long periods.