Vol.:(0123456789) Bulletin of Earthquake Engineering (2019) 17:2767–2786 https://doi.org/10.1007/s10518-019-00554-y 1 3 ORIGINAL RESEARCH Efect of displacement restraint on the collapse performance of seismically isolated buildings Shoma Kitayama 1  · Michael C. Constantinou 2 Received: 1 October 2018 / Accepted: 5 January 2019 / Published online: 8 January 2019 © Springer Nature B.V. 2019 Abstract This study investigates the efect of displacement restraint on the collapse performance of seismically isolated buildings. The displacement restraints considered are stifening triple Friction Pendulum (FP) bearings and moat walls. The study is based on 6-story perimeter frame seismically isolated buildings designed with special concentrically braced frames (SCBF) and special moment resisting frames (SMF) for a location in California using the minimum criteria of ASCE/SEI 7-10 and ASCE/SEI 7-16 and also using enhanced designs. Results from pushover analysis and nonlinear response history analysis demonstrate that proper designs require a balance between the value of R I for the design of the superstruc- ture and the displacement capacity of the isolators. The paper shows that isolation sys- tems with sufcient displacement capacity before engaging the displacement restraint and a R I factor consistent to that displacement capacity may have an acceptable collapse risk. Values of the design parameters for the superstructure and the displacement capacity and behavior of the isolation system for achieving acceptable collapse risk are presented. Keywords Seismic isolation · ASCE/SEI 7 standard · Friction pendulum isolator · Moat walls · Displacement restraint · Collapse probability 1 Introduction Standards for the analysis and design of seismically isolated buildings or the design and testing of seismic isolation hardware either allow but do not require the use of isolator displacement restraint (ASCE 2010, 2017) or prohibit displacement restraints (CEN 2009; Section 8.3.1.2.3). Recent studies have shown that displacement restraint by either the use of stifening isolators or the use of moat walls has an important efect in achieving accept- able collapse performance (FEMA 2009; Masroor and Mosqueda 2015; Shao et al. 2017; Kitayama and Constantinou 2018a, b). * Shoma Kitayama shomakit@bufalo.edu 1 Department of Civil, Structural and Environmental Engineering, 131 Ketter Hall, University at Bufalo, State University of New York, Bufalo, NY 14260, USA 2 Department of Civil, Structural and Environmental Engineering, 132 Ketter Hall, University at Bufalo, State University of New York, Bufalo, NY 14260, USA