Extreme of structural characteristic factor to reduce seismic forces due to energy absorbing capacity

Many seismic codes in the world adopt a factor that is to reduce seismic design forces considering an energy absorbing capacity of a structure, e.g. R in U.S. and Ds in Japan. Though the concept of the factor is well recognized, the value varies much. This is one of the largest differences between the seismic codes in the world. This paper discusses the background of the factor and to what extent the seismic forces can be reduced due to energy absorbing capacity.