Seismic collapse risk of RC-timber hybrid building with consideration of NBCC 2020 seismic hazard model

Abstract

The latest seismic hazard model described in the 2020 National Building Code of Canada (NBCC) marks a comprehensive improvement over its predecessor (NBCC 2015). For different regions in Canada, this will have an impact on the design of new buildings and performance assessment of existing ones. In the present study, this impact is quantified for a recently developed hybrid building system of cross-laminated timber (CLT) and reinforced concrete (RC) with steel slit dampers. The six-story CLT-RC dual frame, designed using the direct displacement-based method, is located in Vancouver, Canada. Along with a very high seismicity, southwestern British Columbia is characterized by complex seismotectonics consisting of subduction, shallow crustal, and in-slab faulting mechanisms. With the NBCC 2015 and 2020 models, a hazard-consistent set of 40 pairs of ground motion records is selected from the PEER and KiK-net databases, and used to estimate the building’s seismic risk performance. The collapse capacity of the building reveals the need for the use of site-specific ground motion selection for sites with a complex seismicity. The results also indicate that the combination of CLT and steel slit dampers enhances the seismic performance of the hybrid system. The probability of collapse at a hazard level corresponding to a 2475 year return period event is estimated to be 2.7%.