With examples of three 6-storey RC frames by using an elasto-plastic dynamic analysis program PL-AFJD of plane frame

developed by the second author of this paper

the frames designed for different earthquake-intensity regions (intensity category 7

8

9 respectively) are analyzed nonlinearly under four ground motions at the action of rare earthquake. Three frames strictly conform to the National Standard GBJ10-89 and the dimensions of columns are changed once along the height. The structure designed on intensity category 7 shows a relatively small response

which could be sustained by the structure. Though the hinge formation in columns can not be prevented

the inelastic deformation of columns is not serious

the structure at intensity category 9 exhibits a relative strong response

but the deformation of most columns is within the capacity and the trend to form a soft-storey does not appear. It is the structure at intensity category 8 that shows a severe response. Though the visible soft-storey can not be found

the deformation of some columns is beyond the capacity of inelastic hysteretic deformation under certain inputs

which indicate the possibility of local collapse.The elementary analysis results demonstrate the different effectiveness of seismic provisions for three different earthquake-intensity regions

which may be a reference to the amendment of National Design Standard.