Vol.:(0123456789) Bulletin of Earthquake Engineering https://doi.org/10.1007/s10518-018-0446-1 1 3 CASE STUDY REPORTS Sensitivity of surface hazard to diferent factors and site response analysis approaches: a case study for a soft rock site A. Lessi‑Cheimariou 1  · I. J. Tromans 1  · E. Rathje 2  · C. Robertson 3 Received: 15 February 2018 / Accepted: 6 August 2018 © Springer Nature B.V. 2018 Abstract Near-surface efects for a soft rock site (average shear-wave velocity of the top 30 m, Vs 30 ≈ 800 m/s) for a proposed nuclear power station in the UK are integrated into the “bedrock” results of a probabilistic seismic hazard analysis (PSHA) by application of US Nuclear Regulatory Commission (USNRC) Approach 3 and employing a partially non- ergodic PSHA. The sensitivity of the surface hazard to the site response analysis method is assessed, employing both random vibration theory (RVT) and time series (TS) approaches. The efects of diferent assumptions relating to strong-motion duration, selection of target frequency in the surface uniform hazard spectrum (UHS) and the incorporation of the vari- ability of site properties through Monte Carlo simulations are also quantifed. The results show that for the examined stif site, with response concentrated at high frequencies, the use of RVT site response analysis does not introduce a systematic bias in the low frequency ground motion predictions and the duration used in the defnition of the input ground motions is demonstrated to have a secondary efect on the site response. The incorporation of the variability of site properties and the selection of the target frequencies in the convo- lution are shown to be important in the derivation of the uniform hazard spectrum. Keywords Site response analysis · Random vibration theory · Time series · Nuclear design 1 Introduction Lately, the partially non ergodic approach (Rodriguez-Marek et al. 2013, 2014) has become the preferred approach for PSHA for critical facilities in a number of jurisdictions and has been adopted in several recent major projects around the world for instance the Thyspunt Nuclear Power Plant, South Africa (Rodriguez-Marek et al. 2014) the Hanford Nuclear Production Complex, USA (PNNL 2014) and the BC Hydro dam sites, Canada (BC Hydro 2012). * A. Lessi-Cheimariou Angeliki.LessiCheimariou@jacobs.com 1 Jacobs (Former CH2M), 43 Brook Green, London W6 7EF, UK 2 Department of Civil, Architectural and Environmental Engineering, University of Texas at Austin, 301E. Dean Keeton St. Stop C1700, Austin, TX 78712-0273, USA 3 NNB GenCo, Bridgewater House, Counterslip, Bristol BS1 6BX, UK