Redundancy‐Based Seismic Safety Evaluation of Seismically Isolated Buildings

The occurrence of earthquake ground motions exceeding the assumed design level may lead to the yielding of the superstructure of seismically isolated buildings (SIBs). It is known that the yielding of the superstructure is accompanied by a rapid development of deformation (quasi‐brittle). In this paper, the relationship between the D s value (the ratio of the superstructure yield shear force to its maximum elastic response shear) and the ductility factor is determined using incremental dynamic analysis, and the nature of quasi‐brittle is quantified by formulating this relationship. Furthermore, a seismic safety evaluation method for the limit state of the seismic isolation layer and superstructure in SIBs is proposed using this relationship.