Review of Methodologies for Displacement Checks in Modern Seismic Design Codes

This review paper discusses the procedures for evaluating the design displacement given in various design codes from seismically prone countries around the world (the United States, New Zealand, Chile, Japan, Greece, Italy, Iran, India, Turkey, and Romania). The limit displacements and the corresponding limit states are also presented and analyzed in this study besides the importance class factors considered in the selected seismic design codes. A presentation of the behavior factors necessary for evaluating the design value of the seismic action is also shown in this study. One of the observations of this review paper is that there are significant similarities in terms of the approach to the displacement check in the analyzed codes. In addition, it was observed that the displacement check is generally associated with the serviceability limit state (e.g., damage limitation). However, differences in terms of the mean return period for the serviceability check action were observed among the analyzed seismic design codes. Several aspects which have to be further adapted in the future versions of seismic design codes are also discussed in this review paper. One of the main aspects which must be further discussed is the enforcement of displacement limits, which are dependent on the structural system and on the importance of the class/height regime for the ultimate/serviceability limit state. In addition, the dependence of the T-D control period on the probabilistic seismic hazard ordinates should be further discussed. Moreover, the pulse effects, which can affect both the acceleration and the displacement design of response spectra, should be accounted for as well in future generations of seismic codes. Finally, it appears necessary to perform a harmonization of the behavior factors employed in seismic design codes.