Long-period structures may go into elasto-plastic state due to strong earthquakes with structural stiffness degraded and

period prolonged. The fitting degree between seismic response spectrum and the response spectrum of Structure Seismic Design Codes in

the long period may have a great influence on the judgment of structural safety. In this study, the fitting coefficient for long-period

response spectrum may be referred during the ground motion selection for elasto-plastic time-history analysis of long-period structure.

Based on the statistical analysis of six thousands of strong ground motion records, we can obtain seismic wave library, which is

suitable for elasto-plastic time-history analysis of long-period structure in different site conditions. In the obtained seismic wave

library, the response spectrum of the selected seismic waves can be guaranteed to be consistent with the response spectrum in code

during the period of 3~6s.