Three ductility degrees and corresponding force modification factors for different structure types are suggested in foreign seismic codes,and take into account overstrength factor varied.

• 根据结构类型、延性等级以及结构的超静定次数的不同考虑了不同程度的超强,并对超静定次数偏少的结构采用偏低的地震力降低系数。