| In 1991, The “Draft of Guidelines for Seismic Design of Embankment Dams” was drawn up in Japan. The Draft of Guidelines was established as the future design method for new dams, but it can be used for relatively evaluation of the seismic safety of existing dams. In the Draft of Guidelines, a modified seismic coefficient method is proposed as a seismic performance evaluation method for embankment dams in Japan with a height less than 100m, in which the vertical distribution of seismic force was determined with taking the seismic response of dam body into account. The seismic force coefficient was formulated through the examination and analysis of only eight seismic motions recorded at dam sites during actual relatively large earthquakes. But, since the implementation of the Draft of Guidelines, a number of seismic motions have been recorded at many dam sites in Japan. In our research, we re-examined seismic force coefficients using recent seismic motion records and proposed revised seismic force coefficients for a modified seismic coefficient method intended also for embankment dams greater than 100 m in dam height. |
