1 INTRODUCTION Over the years, seismic design criteria have been evolving primarily in response to the lessons learned from past earthquakes. The evolution of the seismic design provisions during the 1990s has led to the development of the performance-based design (PBD) approach.1 Contrary to the prescriptive design approach where the structural performance is specified at only the traditional life-safety level, in PBD, structures are designed to achieve multi-level target performance objectives.
